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Sample records for high voltage insulation

  1. Insulators for high voltages

    SciTech Connect

    Looms, J.S.T.

    1987-01-01

    This book describes electrical insulators for high voltage applications. Topics considered include the insulating materials, the manufacture of wet process porcelain, the manufacture of tempered glass, the glass-fibre core, the polymeric housing, the common problem - terminating an insulator, mechanical constraints, the physics of pollution flashover, the physics of contamination, testing of insulators, conclusions from testing, remedies for flashover, insulators for special cases, interference and noise, and the insulator of the future.

  2. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  3. High Voltage Insulation Technology

    NASA Astrophysics Data System (ADS)

    Scherb, V.; Rogalla, K.; Gollor, M.

    2008-09-01

    In preparation of new Electronic Power Conditioners (EPC's) for Travelling Wave Tub Amplifiers (TWTA's) on telecom satellites a study for the development of new high voltage insulation technology is performed. The initiative is mandatory to allow compact designs and to enable higher operating voltages. In a first task a market analysis was performed, comparing different materials with respect to their properties and processes. A hierarchy of selection criteria was established and finally five material candidates (4 Epoxy resins and 1 Polyurethane resin) were selected to be further investigated in the test program. Samples for the test program were designed to represent core elements of an EPC, the high voltage transformer and Printed Circuit Boards of the high voltage section. All five materials were assessed in the practical work flow of the potting process and electrical, mechanical, thermal and lifetime testing was performed. Although the lifetime tests results were overlayed by a larges scatter, finally two candidates have been identified for use in a subsequent qualification program. This activity forms part of element 5 of the ESA ARTES Programme.

  4. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  5. Cryogenic High Voltage Insulation Breaks for ITER

    NASA Astrophysics Data System (ADS)

    Kovalchuk, O. A.; Safonov, A. V.; Rodin, I. Yu.; Mednikov, A. A.; Lancetov, A. A.; Klimchenko, Yu. A.; Grinchenko, V. A.; Voronin, N. M.; Smorodina, N. V.; Bursikov, A. S.

    High voltage insulation breaks are used in cryogenic lines with gas or liquid (helium, hydrogen, nitrogen, etc.) at a temperature range of 4.2-300 K and pressure up to 30 MPa to insulate the parts of an electrophysical facility with different electrical potentials. In 2013 JSC "NIIEFA" delivered 95 high voltage insulation breaks to the IO ITER, i.e. 65 breaks with spiral channels and 30 breaks with uniflow channels. These high voltage insulation breaks were designed, manufactured and tested in accordance with the ITER Technical Specifications: «Axial Insulating Breaks for the Qualification Phase of ITER Coils and Feeders». The high voltage insulation breaks consist of the glass-reinforced plastic cylinder equipped with channels for cryoagent and stainless steel end fittings. The operating voltage is 30 kV for the breaks with spiral channels (30 kV HV IBs) and 4 kV for the breaks with uniflow channels (4 kV HV IBs). The main design feature of the 30 kV HV IBs is the spiral channels instead of a linear one. This approach has enabled us to increase the breakdown voltage and decrease the overall dimensions of the high voltage insulation breaks. In 2013 the manufacturing technique was developed to produce the high voltage insulation breaks with the spiral and uniflow channels that made it possible to proceed to serial production. To provide the acceptance tests of the breaks a special test facility was prepared. The helium tightness test at 10-11 m3Pa/s under the pressure up to 10 MPa, the high voltage test up to 135 kV and different types of mechanical tests were carried out at the room and liquid nitrogen temperatures.

  6. Gaseous insulators for high voltage electrical equipment

    DOEpatents

    Christophorou, Loucas G.; James, David R.; Pace, Marshall O.; Pai, Robert Y.

    1979-01-01

    Gaseous insulators comprise compounds having high attachment cross sections for electrons having energies in the 0-1.3 electron volt range. Multi-component gaseous insulators comprise compounds and mixtures having overall high electron attachment cross sections in the 0-1.3 electron volt range and moderating gases having high cross sections for inelastic interactions with electrons of energies 1-4 electron volts. Suitable electron attachment components include hexafluorobutyne, perfluorobutene-2, perfluorocyclobutane, perfluorodimethylcyclobutane, perfluorocyclohexene, perfluoromethylcyclohexane, hexafluorobutadiene, perfluoroheptene-1 and hexafluoroazomethane. Suitable moderating gases include N.sub.2, CO, CO.sub.2 and H.sub.2. The gaseous insulating mixture can also contain SF.sub.6, perfluoropropane and perfluorobenzene.

  7. Gaseous insulators for high voltage electrical equipment

    DOEpatents

    Christophorou, Loucas G.; James, David R.; Pace, Marshall O.; Pai, Robert Y.

    1981-01-01

    Gaseous insulators comprise compounds having high attachment cross sections for electrons having energies in the 0-1.3 electron volt range. Multi-component gaseous insulators comprise compounds and mixtures having overall high electron attachment cross sections in the 0-1.3 electron volt range and moderating gases having high cross sections for inelastic interactions with electrons of energies 1-4 electron volts. Suitable electron attachment components include hexafluorobutyne, perfluorobutene-2, perfluorocyclobutane, perfluorodimethylcyclobutane, perfluorocyclohexene, perfluoromethylcyclohexane, hexafluorobutadiene, perfluoroheptene-1 and hexafluoroazomethane. Suitable moderating gases include N.sub.2, CO, CO.sub.2 and H.sub.2. The gaseous insulating mixture can also contain SF.sub.6, perfluoropropane and perfluorobenzene.

  8. High voltage gas insulated transmission line with continuous particle trapping

    DOEpatents

    Cookson, Alan H.; Dale, Steinar J.

    1983-01-01

    This invention provides a novel high voltage gas insulated transmission line utilizing insulating supports spaced at intervals with snap-in means for supporting a continuous trapping apparatus and said trapping apparatus having perforations and cutouts to facilitate trapping of contaminating particles and system flexibility.

  9. High voltage insulation of bushing for HTS power equipment

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Jin; Choi, Jae-Hyeong; Kim, Sang-Hyun

    2012-12-01

    For the operation of high temperature superconducting (HTS) power equipments, it is necessary to develop insulating materials and high voltage (HV) insulation technology at cryogenic temperature of bushing. Liquid nitrogen (LN2) is an attractive dielectric liquid. Also, the polymer insulating materials are expected to be used as solid materials such as glass fiber reinforced plastic (GFRP), polytetra-fluoroethylene (PTFE, Teflon), Silicon (Si) rubber, aromatic polyamide (Nomex), EPDM/Silicon alloy compound (EPDM/Si). In this paper, the surface flashover characteristics of various insulating materials in LN2 are studied. These results are studied at both AC and impulse voltage under a non-uniform field. The use of GFRP and Teflon as insulation body for HTS bushing should be much desirable. Especially, GFRP is excellent material not only surface flashover characteristics but also mechanical characteristics at cryogenic temperature. The surface flashover is most serious problem for the shed design in LN2 and operation of superconducting equipments.

  10. Understanding High Voltage Vacuum Insulators for Microsecond Pulses

    SciTech Connect

    J.B., J; D.A., G; T.L., H; E.J., L; R.D., S; L.K., T; G.E., V

    2007-08-15

    High voltage insulation is one of the main areas of pulsed power research and development since the surface of an insulator exposed to vacuum can fail electrically at an applied field more than an order or magnitude below the bulk dielectric strength of the insulator. This is troublesome for applications where high voltage conditioning of the insulator and electrodes is not practical and where relatively long pulses, on the order of several microseconds, are required. Here we give a summary of our approach to modeling and simulation efforts and experimental investigations for understanding flashover mechanism. The computational work is comprised of both filed and particle-in-cell modeling with state-of-the-art commercial codes. Experiments were performed in using an available 100-kV, 10-{micro}s pulse generator and vacuum chamber. The initial experiments were done with polyethylene insulator material in the shape of a truncated cone cut at +45{sup o} angle between flat electrodes with a gap of 1.0 cm. The insulator was sized so there were no flashovers or breakdowns under nominal operating conditions. Insulator flashover or gap closure was induced by introducing a plasma source, a tuft of velvet, in proximity to the insulator or electrode.

  11. Novel cryogenic high voltage insulation breaks with spiral channel

    NASA Astrophysics Data System (ADS)

    Bursikov, A. S.; Voronin, N. M.; Gavrilov, S. M.; Grinchenko, V. A.; Klimchenko, Yu. A.; Korsunskiy, V. A.; Kovalchuk, O. A.; Lancetov, A. A.; Marushin, E. L.; Mednikov, A. A.; Rodin, I. Yu.; Safonov, A. V.

    2014-01-01

    Insulation breaks are used in cryogenic lines with a gas or liquid at temperatures of 4.2-300 K and pressure up to 30 MPa to isolate the parts of electrophysical setup with different electrical potential. Novel cryogenic high voltage (HV) insulation breaks for the electrophysical equipment that uses the effect of superconductivity was developed in the D.V. Efremov Institute of Electrophysical Apparatus (NIIEFA). These insulation breaks consist of glass-reinforced plastic cylinder equipped with channel for cryoagent and stainless steel end fittings. The main design feature of new kind HV break is spiral channel instead of linear one. This approach allowed to increase the breakdown voltage and to decrease the overall dimensions of insulation breaks. The design length of the spiral channel depends on HV requirements and the kind of cryoagent. To provide the wide range of operating voltages, temperatures and pressures the insulation breaks with various dimensions were developed. To provide an acceptance test of breaks as manufactured the special test facility was prepared. Helium tightness test with a level 1.2ṡ10-11 m3ṡPa/s under up to 30 MPa, HV test up to 135 kV and different kinds of mechanical tests could be provided at room and liquid nitrogen temperatures.

  12. Understanding and Improving High Voltage Vacuum Insulators for Microsecond Pulses

    SciTech Connect

    Javedani, J B; Goerz, D A; Houck, T L; Lauer, E J; Speer, R D; Tully, L K; Vogtlin, G E; White, A D

    2007-03-05

    High voltage insulation is one of the main areas of pulsed power research and development, and dielectric breakdown is usually the limiting factor in attaining the highest possible performance in pulsed power devices. For many applications the delivery of pulsed power into a vacuum region is the most critical aspect of operation. The surface of an insulator exposed to vacuum can fail electrically at an applied field more than an order or magnitude below the bulk dielectric strength of the insulator. This mode of breakdown, called surface flashover, imposes serious limitations on the power flow into a vacuum region. This is especially troublesome for applications where high voltage conditioning of the insulator and electrodes is not practical and for applications where relatively long pulses, on the order of several microseconds, are required. The goal of this project is to establish a sound fundamental understanding of the mechanisms that lead to surface flashover, and then evaluate the most promising techniques to improve vacuum insulators and enable high voltage operation at stress levels near the intrinsic bulk breakdown limits of the material. The approach we proposed and followed was to develop this understanding through a combination of theoretical and computation methods coupled with experiments to validate and quantify expected behaviors. In this report we summarize our modeling and simulation efforts, theoretical studies, and experimental investigations. The computational work began by exploring the limits of commercially available codes and demonstrating methods to examine field enhancements and defect mechanisms at microscopic levels. Plasma simulations with particle codes used in conjunction with circuit models of the experimental apparatus enabled comparisons with experimental measurements. The large scale plasma (LSP) particle-in-cell (PIC) code was run on multiprocessor platforms and used to simulate expanding plasma conditions in vacuum gap regions

  13. Micalastic high-voltage insulation: Design features and experience

    NASA Astrophysics Data System (ADS)

    Wichmann, A.

    1981-12-01

    High-quality mica, carefully selected epoxy resins and a well-matched vacuum/pressure impregnation process determine the characteristics of the MICALASTIC insulation for large turbine-generators. Logical development and process manufacturing quality control have led to an insulation system of high quality and operating reliability. The first winding of a turbine-generator being impregnated and cured under vacuum with solvent-free synthetic resin in 1958 was designed for 10.5 kV rated voltage. Ever since, Siemens AG and Kraftwerk Union AG have used this type of insulation for all direct-cooled windings and also for an increasing number of indirect-cooled windings. At present, 240 turbine-generators with a total of more than 115,000 MVA output have been built. Since 1960, this insulation system has been registered for Siemens AG under the trade name MICALASTIC. The stator windings of the largest, single-shaft generators to date, rated 1560 MVA, 27 kV, has been built with MICALASTIC insulation.

  14. Self-monitoring high voltage transmission line suspension insulator

    DOEpatents

    Stemler, Gary E.; Scott, Donald N.

    1981-01-01

    A high voltage transmission line suspension insulator (18 or 22) which monitors its own dielectric integrity. A dielectric rod (10) has one larger diameter end fitting attachable to a transmission line and another larger diameter end fitting attachable to a support tower. The rod is enclosed in a dielectric tube (14) which is hermetically sealed to the rod's end fittings such that a liquidtight space (20) is formed between the rod and the tube. A pressurized dielectric liquid is placed within that space. A discoloring dye placed within this space is used to detect the loss of the pressurized liquid.

  15. SECONDARY ELECTRON TRAJECTORIES IN HIGH-GRADIENT VACUUM INSULATORS WITH FAST HIGH-VOLTAGE PULSES

    SciTech Connect

    Chen, Y; Blackfield, D; Nelson, S D; Poole, B

    2010-04-21

    Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. Primary or secondary electrons (emitted from the insulator surface) can be deflected by magnetic fields from external sources, the high-current electron beam, the conduction current in the transmission line, or the displacement current in the insulator. These electrons are deflected either toward or away from the insulator surface and this affects the performance of the vacuum insulator. This paper shows the effects of displacement current from short voltage pulses on the performance of high gradient insulators. Generally, vacuum insulator failure is due to surface flashover, initiated by electrons emitted from a triple junction. These electrons strike the insulator surface thus producing secondary electrons, and can lead to a subsequent electron cascade along the surface. The displacement current in the insulator can deflect electrons either toward or away from the insulator surface, and affects the performance of the vacuum insulator when the insulator is subjected to a fast high-voltage pulse. Vacuum insulators composed of alternating layers of metal and dielectric, known as high-gradient insulators (HGIs), have been shown to withstand higher electric fields than conventional insulators. HGIs, being tolerant of the direct view of high-current electron and ion beams, and having desirable RF properties for accelerators, are a key enabling technology for the dielectric-wall accelerators (DWA) being developed at Lawrence Livermore National Laboratory (LLNL). Characteristically, insulator surface breakdown thresholds go up as the applied voltage pulse width decreases. To attain the highest accelerating gradient in the DWA, short accelerating voltage pulses are only applied locally, along the HGI accelerator tube, in sync with the charged particle bunch, and the effects of

  16. Photoconductivity of high-voltage space insulating materials

    NASA Technical Reports Server (NTRS)

    Coffey, H. T.; Nanevicz, J. E.; Adamo, R. C.

    1975-01-01

    The dark and photoconductivities of four high voltage spacecraft insulators, Kapton-H, FEP Teflon, Parylene, and fused quartz, were studied under a variety of conditions intended to simulate a space environment. All measurements were made in a vacuum of less than .00001 torr while the temperature was varied from 22 C to 100 C. Some of the samples used employed conventional deposited metal electrodes--others employed electrodes composed either of an electron beam or a plasma formed by ionization of the residual gas in the test chamber. Test results show: (1) Kapton had unusual conduction properties; it conductivity decreased by more than an order of magnitude when heated at 100 C in a vacuum, but ultimately attained a stable and reproducible value. (2) Both Teflon and fused quartz had high dark resistivities but low photoresistivities when exposed to UV. Optical-density measurements revealed that both materials transmitted UV with little attenuation. (3) Parylene was found to have a low but relatively stable resistivity--comparatively minor changes occurred upon heating or illuminating the sample. Optical-density measurements showed that Parylene was absorbent in the UV and would prevent photoemission from the metal electrode on the back surface.

  17. Risk assessment of desert pollution on composite high voltage insulators.

    PubMed

    El-Shahat, Mohammed; Anis, Hussein

    2014-09-01

    Transmission lines located in the desert are subjected to desert climate, one of whose features is sandstorms. With long accumulation of sand and with the advent of moisture from rain, ambient humidity and dew, a conductive layer forms and the subsequent leakage current may lead to surface discharge, which may shorten the insulator life or lead to flashover thus interrupting the power supply. Strategically erected power lines in the Egyptian Sinai desert are typically subject to such a risk, where sandstorms are known to be common especially in the spring. In view of the very high cost of insulator cleaning operation, composite (silicon rubber) insulators are nominated to replace ceramic insulators on transmission lines in Sinai. This paper examines the flow of leakage current on sand-polluted composite insulators, which in turn enables a risk assessment of insulator failure. The study uses realistic data compiled and reported in an earlier research project about Sinai, which primarily included grain sizes of polluting sand as well as their salinity content. The paper also uses as a case study an ABB-designed composite insulator. A three-dimensional finite element technique is used to simulate the insulator and seek the potential and electric field distribution as well as the resulting leakage current flow on its polluted surface. A novel method is used to derive the probabilistic features of the insulator's leakage current, which in turn enables a risk assessment of insulator failure. This study is expected to help in critically assessing - and thus justifying - the use of this type of insulators in Sinai and similar critical areas. PMID:25685525

  18. Development of large high-voltage pressure insulators for the princeton TFTR flexible transmission lines

    NASA Astrophysics Data System (ADS)

    Scalise, D. T.; Fong, E.; Haughian, J.; Prechter, R.

    1987-04-01

    Specially formulated insulator materials with improved strength and high-voltage properties were developed and used for critical components of the flexible transmission lines to the TFTR neutral beam ion sources. These critical components are plates which support central conductors as they exit the high-voltage power supply and enter the ion source enclosure. Each plate acts both as a high-voltage insulator and as a pressure barrier to the SF 6 insulating gas. The original plate was made of commercial glass-epoxy laminate which limited the plate voltage capacity. The newly developed insulator is made of specially-formulated cycloalphatic di-epoxide whose isotropic properties exhibit increased are resistance. It is cast in one piece with skirts which greatly increase the breakdown voltage. This paper discusses the design, fabrication and testing of the new insulator.

  19. Smaller insulators handle higher voltage

    SciTech Connect

    Wilt, G.

    1997-10-01

    Researcher at Lawrence Livermore have designed the Ultra High Gradient Insulator, a device that can reliably withstand electrical voltages four times greater than before. The Ultra-HGI is designed with alternating layers which divide voltages so finely that the chances of failure are small, and when they do occur, they are confined to a very small portion of the insulator.

  20. Evaluation of Epoxy Nanocomposites for High Voltage Insulation

    NASA Astrophysics Data System (ADS)

    Iyer, Ganpathy

    Polymeric materials containing nanometer (nm) size particles are being introduced to provide compact shapes for low and medium voltage insulation equipment. The nanocomposites may provide superior electrical performance when compared with those available currently, such as lower dielectric losses and increased dielectric strength, tracking and erosion resistance, and surface hydrophobicity. All of the above mentioned benefits can be achieved at a lower filler concentration (< 10%) than conventional microfillers (40-60%). Also, the uniform shapes of nanofillers provide a better electrical stress distribution as compared to irregular shaped microcomposites which can have high internal electric stress, which could be a problem for devices with active electrical parts. Improvement in electrical performance due to addition of nanofillers in an epoxy matrix has been evaluated in this work. Scanning Electron Microscopy (SEM) was done on the epoxy samples to confirm uniform dispersion of nano-sized fillers as good filler dispersion is essential to realize the above stated benefits. Dielectric spectroscopy experiments were conducted over a wide range of frequencies as a function of temperature to understand the role of space charge and interfaces in these materials. The experiment results demonstrate significant reduction in dielectric losses in samples containing nanofillers. High voltage experiments such as corona resistance tests were conducted over 500 hours to monitor degradation in the samples due to corona. These tests revealed improvements in partial discharge endurance of nanocomposite samples. These improvements could not be adequately explained using a macroscopic quantity such as thermal conductivity. Thermo gravimetric analysis (TGA) showed higher weight loss initiation temperatures for nanofilled samples which is in agreement with the corona resistance experimental results. Theoretical models have also been developed in this work to complement the results of

  1. Experimental study and mathematical modelling of flashover on extra-high voltage insulators covered with ice

    NASA Astrophysics Data System (ADS)

    Farzaneh-Dehkordi, J.; Zhang, J.; Farzaneh, M.

    2004-12-01

    Using a test method developed at the high-voltage laboratory of the NSERC/Hydro-Quebec/UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE), the relation between the minimum flashover voltage VMF and the insulator dry arcing distance for standard porcelain station post insulators, as typically used in Hydro-Quebec substations, was investigated under icing conditions. The experimental results show that, under wet-grown ice, known as the most dangerous type of ice for power transmission systems, the VMF increases nonlinearly with an increase in insulator length. Based on these results, an improved mathematical model for predicting the critical flashover voltage versus length of ice-covered insulators is presented. This model is helpful for understanding the flashover phenomenon on ice-covered insulators and presents a powerful tool for choosing the proper length of outdoor insulators in cold climate regions. Copyright

  2. Conductivity Variation Observed by Polarization and Depolarization Current Measurements of High-Voltage Equipment Insulation System

    NASA Astrophysics Data System (ADS)

    Jamail, Nor Akmal Mohd; Piah, Mohamed Afendi Mohamed; Muhamad, Nor Asiah

    2012-09-01

    Nondestructive and time domain dielectric measurement techniques such as polarization and depolarization current (PDC) measurements have recently been widely used as a potential tool for determining high-voltage insulation conditions by analyzing the insulation conductivity. The variation in the conductivity of an insulator was found to depend on several parameters: the difference between the polarization and depolarization currents, geometric capacitance, and the relative permittivity of the insulation material. In this paper the conductivities of different types of oil-paper insulation material are presented. The insulation conductivities of several types of electrical apparatus were simulated using MATLAB. Conductivity insulation was found to be high at high polarizations and at the lowest depolarization current. It was also found to increase with increasing relative permittivity as well as with decreasing geometric capacitance of the insulating material.

  3. Fast thermonuclear ignition with two nested high current lower voltage - high voltage lower current magnetically insulated transmission lines

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    2003-11-01

    Fast thermonuclear ignition with a high gain seems possible with two Marx generators feeding two nested magnetically insulated transmission lines, one delivering a high current lower voltage pulse for compression and confinement, and one delivering a high voltage lower current pulse for fast ignition. With an input energy conceivably as small as 100 kJ the gain can be as large as 10 3. The concept not only would be by orders of magnitude less expensive than laser compression and fast ignition schemes, but because of the large gain with a small yield also be more suitable for a thermonuclear reactor.

  4. Polarization of vacuum-pressure-impregnated high voltage epoxy-mica insulations

    SciTech Connect

    Keskinen, E.; Jaeppinen, J.

    1996-12-31

    In this paper the electrical behavior of modern epoxy-mica high voltage insulation is investigated with the help of two-layer insulation model. The simplified model help to understand the charging phenomenon in actual high voltage insulation. The behavior of Vacuum-Pressure-Impregnated (VPI`ed) epoxy-mica insulation is compared with Shellac-Micafolium insulation. It is illustrated that because of higher volume resistivity the rate of change of the field distribution due to charging is considerably slower in epoxy-mica insulation. This tends to result in lower polarization index (PI) value for the epoxy-mica insulation than typically obtained for Shellac-Micafolium insulations. It is also illustrated that the faster PI measurement method (ratio of the 60 seconds value to the 15 seconds value) gives clearly lower PI value than the method defined in IEEE 43 (1974) (ratio of 600 s value to 60 s value). Finally, the effect of moisture on insulation resistance and PI of VPI`ed epoxy-mica winding insulation is discussed.

  5. Propylene based systems for high voltage cable insulation applications

    NASA Astrophysics Data System (ADS)

    Hosier, I. L.; Cozzarini, L.; Vaughan, A. S.; Swingler, S. G.

    2009-08-01

    Crosslinked polyethylene (XLPE) remains the material of choice for extruded high voltage cables, possessing excellent thermo-mechanical and electrical properties. However, it is not easily recyclable posing questions as to its long term sustainability. Whilst both polyethylene and polypropylene are widely recycled and provide excellent dielectric properties, polypropylene has significantly better mechanical integrity at high temperatures than polyethylene. However, while isotactic polypropylene is too stiff at room temperature for incorporation into a cable system, previous studies by the authors have indicated that this limitation can be overcome by using a propylene-ethylene copolymer. Whilst these previous studies considered unrelated systems, the current study aims to quantify the usefulness of a series of related random propylene-ethylene co-polymers and assesses their potential for replacing XLPE.

  6. New live line tester for porcelain suspension insulators on high-voltage power lines

    SciTech Connect

    Vaillancourt, G.H.; St-Jean, M. ); Bellerive, J.P. ); Jean, C. )

    1994-01-01

    Suspension insulator assemblies known as insulator strings are used in overhead power transmission lines to mechanically support high-voltage conductors while providing adequate insulation to withstand switching and lightning overvoltages. Since the useful life in service of the individual insulator elements making up these strings is hard to predict, they must be verified periodically to insure that adequate line reliability is maintained at all times. Over the years many testing methods have been used for this purpose, each one with its own advantages and disadvantages. Until now at Hydro-Quebec, porcelain insulators had been tested by the buzz method which simply consists of applying a short-circuit to each insulator in a string and listening for a buzz-like sound indicating a good insulator. However, safety considerations that preclude short-circuiting insulators and other disadvantages of that method have led Hydro-Quebec to undertake and complete the development of a new insulator tester. The working principle of this new device is based on the automatic measurement and recording of the electric field along the insulator string which decreases considerably in front of an internally-shorted insulator. The tester is slid along the string while the insulators are counted automatically. The information from tests on up to 200 strings can be stored in the device to be later transferred in a host computer for interpretation and/or permanent storage. The new tester also gives information on voltage distribution along the insulator strings which can be useful for the design of future power transmission lines.

  7. Characteristics of corona impulses from insulated wires subjected to high ac voltages

    NASA Technical Reports Server (NTRS)

    Doreswamy, C. V.; Crowell, C. S.

    1976-01-01

    Corona discharges arise due to ionization of air or gas subject to high electric fields. The free electrons and ions contained in these discharges interact with molecules of insulating materials, resulting in chemical changes and destroying the electrical insulating properties. The paper describes some results of measurements aimed at determining corona pulse waveforms, their repetition rate, and amplitude distribution during various randomly-sampled identical time periods of a 60-Hz high-voltage wave. Described are properties of positive and negative corona impulses generated from typical conductors at various test high voltages. A possible method for calculating the energies, densities, and electromagnetic interferences by making use of these results is suggested.

  8. Fluorescence lidar imaging of fungal growth on high-voltage outdoor composite insulators

    NASA Astrophysics Data System (ADS)

    Bengtsson, M.; Grönlund, R.; Sjöholm, M.; Abrahamsson, Ch.; Dernfalk, A. D.; Wallström, S.; Larsson, A.; Weibring, P.; Karlsson, S.; Gubanski, S. M.; Kröll, S.; Svanberg, S.

    2005-06-01

    Remote fluorescence imaging of fungal growth on polymeric high-voltage insulators was performed using a mobile lidar system with a laser wavelength of 355 nm. Insulator areas contaminated by fungal growth could be distinguished from clean surfaces and readily be imaged. The experiments were supported by detailed spectral studies performed in laboratory using a fibre-optic fluorosensor incorporating an optical multi-channel analyser system (OMA) and a nitrogen laser emitting radiation at 337 nm.

  9. Determination of threshold and maximum operating electric stresses for selected high voltage insulations. Task III. Investigation of high voltage capacitor insulation. Progress report No. 4

    SciTech Connect

    Sosnowski, M.; Eager, G.S. Jr.

    1984-03-01

    This report covers the investigation of threshold voltage of capacitor insulation. The experimental work was performed on samples prepared from commercial polypropylene insulated, liquid-filled capacitors. The samples were vacuum-impregnated with the original capacitor insulating liquid obtained from the manufacturer. A limited number of full-size capacitor elements also were tested. Impulse voltage breakdown tests with dc voltage prestressing were performed at room temperature and 75/sup 0/C. From the results of these tests, the threshold voltage of the samples of the capacitor insulation was determined at both temperatures and that of the whole capacitor elements at room temperature. The threshold voltage of the capacitor insulation was found to be approximately equal to the impulse breakdown voltage. No difference was found between the threshold voltage at room temperature and at 75/sup 0/C. The threshold voltage of the whole capacitor elements at room temperature was found to be equal to approximately 80% of the threshold voltage of the capacitor insulation samples.

  10. Ternary gas mixtures for high-voltage industrial insulation

    NASA Astrophysics Data System (ADS)

    Pace, M. O.; Chan, C. C.; Christophorou, L. G.

    1981-10-01

    Gas dielectrics for insulating power apparatus, e.g., gas insulated transmission lines (GITL), were evaluated. Particular attention was given to mixtures using large proportions of an electron moderating gas (viz., N2, CHF3, or 1,1,1-C2H3F3) and smaller quantities of two electron attaching gases: SF6 and one fluorocarbon (e.g., c-C4F8). The proportions were sought at which the three gases function best as a team, moderating free electrons from higher to lower energies and there attaching them. Small amounts of the electron attaching additives can drastically raise the dielectric strength of the moderator. Certain combinations of SF6 and fluorocarbons do not produce the undesirable spark by products associated with either SF6 or fluorocarbons alone and also show improved negative polarity impulse breakdown characteristics over pure SF6. Small scale breakdown measurements were made of various ternary mixtures in the GITL geometry. It was found that nitrogen moderates electrons to extremely low energies, where SF6 attaches; the dipolar gases moderate to somewhat higher energies, where some fluorocarbons attach best.

  11. Effects of carbon/graphite fiber contamination on high voltage electrical insulation

    NASA Technical Reports Server (NTRS)

    Garrity, T.; Eichler, C.

    1980-01-01

    The contamination mechanics and resulting failure modes of high voltage electrical insulation due to carbon/graphite fibers were examined. The high voltage insulation vulnerability to carbon/graphite fiber induced failure was evaluated using a contamination system which consisted of a fiber chopper, dispersal chamber, a contamination chamber, and air ducts and suction blower. Tests were conducted to evaluate the effects of fiber length, weathering, and wetness on the insulator's resistance to carbon/graphite fibers. The ability of nuclear, fossil, and hydro power generating stations to maintain normal power generation when the surrounding environment is contaminated by an accidental carbon fiber release was investigated. The vulnerability assessment included only the power plant generating equipment and its associated controls, instrumentation, and auxiliary and support systems.

  12. High voltage instrument transformers for outdoor service with an insulation of low pressure SF6 gas and plastic foils

    NASA Astrophysics Data System (ADS)

    Brand, U.

    1985-04-01

    Gas-insulated failsafe high voltage instrument transformers with system voltages in the range of 123 to 420 kV for outdoor service were developed. The basic physics and high power tests performed on gas-filled instrument transformer housings are discussed. Construction and design of gas-insulated voltage transformers are explained. The insulation of the 123 kV model consists of low pressurized SF6 gas and plastic foils. The 245 kV unit has the same principal design; however, a higher SF6 pressure is used and the apparatus is fitted with a hollow composite insulator made of a fiber reinforced plastics tube and silicone casing. For the 420 kV model the same insulator type is used and a design for the voltage grading along the insulator is developed. The transformers show good performance in service; they are a safe and environment-protecting alternative to oil insulated equipment.

  13. Forecasting of high voltage insulation performance: Testing of recommended potting materials and of capacitors

    NASA Technical Reports Server (NTRS)

    Bever, R. S.

    1984-01-01

    Nondestructive high voltage test techniques (mostly electrical methods) are studied to prevent total or catastrophic breakdown of insulation systems under applied high voltage in space. Emphasis is on the phenomenon of partial breakdown or partial discharge (P.D.) as a symptom of insulation quality, notably partial discharge testing under D.C. applied voltage. Many of the electronic parts and high voltage instruments in space experience D.C. applied stress in service, and application of A.C. voltage to any portion thereof would be prohibited. Suggestions include: investigation of the ramp test method for D.C. partial discharge measurements; testing of actual flight-type insulation specimen; perfect plotting resin samples with controlled defects for test; several types of plotting resins and recommendations of the better ones from the electrical characteristics; thermal and elastic properties are also considered; testing of commercial capaciters; and approximate acceptance/rejection/rerating criteria for sample test elements for space use, based on D.C. partial discharge.

  14. High-voltage electrical apparatus utilizing an insulating gas of sulfur hexafluoride and helium

    DOEpatents

    Wootton, Roy E.

    1980-01-01

    High-voltage electrical apparatus includes an outer housing at low potential, an inner electrode disposed within the outer housing at high potential with respect thereto, and support means for insulatably supporting the inner electrode within the outer housing. Conducting particles contaminate the interior of the outer housing, and an insulating gas electrically insulates the inner electrode from the outer housing even in the presence of the conducting particles. The insulating gas is comprised of sulfur hexafluoride at a partial pressure of from about 2.9 to about 3.4 atmospheres absolute, and helium at a partial pressure from about 1.1 to about 11.4 atmospheres absolute. The sulfur hexafluoride comprises between 20 and 65 volume percent of the insulating gas.

  15. Ultra High Voltage Propellant Isolators and Insulators for JIMO Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Gaier, James R.; Hung, Ching-Cheh; Walters, Patty A.; Sechkar, Ed; Panko, Scott; Kamiotis, Christina A.

    2004-01-01

    Within NASA's Project Prometheus, high specific impulse ion thrusters for electric propulsion of spacecraft for the proposed Jupiter Icy Moon Orbiter (JIMO) mission to three of Jupiter's moons: Callisto, Ganymede and Europa will require high voltage operation to meet mission propulsion. The anticipated approx.6,500 volt net ion energy will require electrical insulation and propellant isolation which must exceed that used successfully by the NASA Solar Electric Propulsion Technology Readiness (NSTAR) Deep Space 1 mission thruster by a factor of approx.6. Xenon propellant isolator prototypes that operate at near one atmosphere and prototypes that operate at low pressures (<100 Torr) have been designed and are being tested for suitability to the JIMO mission requirements. Propellant isolators must be durable to Paschen breakdown, sputter contamination, high temperature, and high voltage while operating for factors longer duration than for the Deep Space 1 Mission. Insulators used to mount the thrusters as well as those needed to support the ion optics have also been designed and are under evaluation. Isolator and insulator concepts, design issues, design guidelines, fabrication considerations and performance issues are presented. The objective of the investigation was to identify candidate isolators and insulators that are sufficiently robust to perform durably and reliably during the proposed JIMO mission.

  16. Differential charging of high-voltage spacecraft - The equilibrium potential of insulated surfaces

    NASA Technical Reports Server (NTRS)

    Katz, I.; Mandell, M. J.

    1982-01-01

    A theory is presented for the steady-state potential of insulated surfaces near exposed high voltages. The term 'insulated surfaces' is used to mean either dielectric surfaces or electrically isolated metallic surfaces. The potential is bounded below by the zero of the material's I-V curve assuming total suppression of secondary electrons, and above by assuming total extraction of secondaries. Within these bounds, the material's surface potential is determined consistently with the solution to Poisson's equation external to the vehicle. The theory is compared with rocket experiments and with SCATHA satellite data. Also, an explanation is suggested for the observed 'snapover' of solar cell coverslips from near plasma ground potential to near the potential of positively biased interconnects with increasing bias voltage.

  17. Differential charging of high-voltage spacecraft: The equilibrium potential of insulated surfaces

    NASA Astrophysics Data System (ADS)

    Katz, I.; Mandell, M. J.

    1982-06-01

    A theory is presented for the steady-state potential of insulated surfaces near exposed high voltages. The term 'insulated surfaces' is used to mean either dielectric surfaces of electrically isolated metallic surfaces. The potential is bounded below by the zero of the material's I-V curve assuming total suppression of secondary electrons, and above by assuming total extraction of secondaries. Within these bounds, the material's surface potential is determined consistently with the solution to Poisson's equation external to the vehicle. The theory is compared with rocket experiments and with SCATHA satellite data. Also, an explanation is suggested for the observed 'snapover' of solar cell coverslips from near plasma ground potential to near the potential of positively biased interconnects with increasing bias voltage.

  18. Initiation of vacuum insulator surface high-voltage flashover with electrons produced by laser illumination

    NASA Astrophysics Data System (ADS)

    Krasik, Ya. E.; Leopold, J. G.

    2015-08-01

    In this paper, experiments are described in which cylindrical vacuum insulator samples and samples inclined at 45° relative to the cathode were stressed by microsecond timescale high-voltage pulses and illuminated by focused UV laser beam pulses. In these experiments, we were able to distinguish between flashover initiated by the laser producing only photo-electrons and when plasma is formed. It was shown that flashover is predominantly initiated near the cathode triple junction. Even dense plasma formed near the anode triple junction does not necessarily lead to vacuum surface flashover. The experimental results directly confirm our conjecture that insulator surface breakdown can be avoided by preventing its initiation [J. G. Leopold et al., Phys. Rev. ST Accel. Beams 10, 060401 (2007)] and complement our previous experimental results [J. Z. Gleizer et al., IEEE Trans. Dielectr. Electr. Insul. 21, 2394 (2014) and J. Z. Gleizer et al., J. Appl. Phys. 117, 073301 (2015)].

  19. Initiation of vacuum insulator surface high-voltage flashover with electrons produced by laser illumination

    SciTech Connect

    Krasik, Ya. E.; Leopold, J. G.

    2015-08-15

    In this paper, experiments are described in which cylindrical vacuum insulator samples and samples inclined at 45° relative to the cathode were stressed by microsecond timescale high-voltage pulses and illuminated by focused UV laser beam pulses. In these experiments, we were able to distinguish between flashover initiated by the laser producing only photo-electrons and when plasma is formed. It was shown that flashover is predominantly initiated near the cathode triple junction. Even dense plasma formed near the anode triple junction does not necessarily lead to vacuum surface flashover. The experimental results directly confirm our conjecture that insulator surface breakdown can be avoided by preventing its initiation [J. G. Leopold et al., Phys. Rev. ST Accel. Beams 10, 060401 (2007)] and complement our previous experimental results [J. Z. Gleizer et al., IEEE Trans. Dielectr. Electr. Insul. 21, 2394 (2014) and J. Z. Gleizer et al., J. Appl. Phys. 117, 073301 (2015)].

  20. High voltage trapping effects in GaN-based metal-insulator-semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Meneghesso, Gaudenzio; Meneghini, Matteo; Silvestri, Riccardo; Vanmeerbeek, Piet; Moens, Peter; Zanoni, Enrico

    2016-01-01

    This paper presents an analysis of the high voltage trapping processes that take place in high-electron mobility transistors based on GaN, with a metal-insulator-semiconductor (MIS) structure. The study is based on combined pulsed and transient measurements, carried out with trapping voltages in the range from 50 to 500 V. The results indicate that: (i) dynamic Ron is maximum for trapping voltages between 200 and 300 V, and decreases for higher voltage levels; (ii) Ron-transient measurements reveal the presence of a dominant trap with activation energy Ea1 = 0.93 eV and of a second trap with activation energy equal to Ea2 = 0.61 eV; (iii) the deep level transient spectroscopy (DLTS) signal associated to trap Ea1 is completely suppressed for high trapping voltages (VDS = 500 V). The results are interpreted by considering that the trap Ea1 is located in the buffer, and originates from CN defects. The exposure to high drain voltages may favor the depletion of such traps, due to a field-assisted de-trapping process or to the presence of vertical leakage paths.

  1. Insulation Requirements of High-Voltage Power Systems in Future Spacecraft

    NASA Technical Reports Server (NTRS)

    Qureshi, A. Haq; Dayton, James A., Jr.

    1995-01-01

    The scope, size, and capability of the nation's space-based activities are limited by the level of electrical power available. Long-term projections show that there will be an increasing demand for electrical power in future spacecraft programs. The level of power that can be generated, conditioned, transmitted, and used will have to be considerably increased to satisfy these needs, and increased power levels will require that transmission voltages also be increased to minimize weight and resistive losses. At these projected voltages, power systems will not operate satisfactorily without the proper electrical insulation. Open or encapsulated power supplies are currently used to keep the volume and weight of space power systems low and to protect them from natural and induced environmental hazards. Circuits with open packaging are free to attain the pressure of the outer environment, whereas encapsulated circuits are imbedded in insulating materials, which are usually solids, but could be liquids or gases. Up to now, solid insulation has usually been chosen for space power systems. If the use of solid insulation is continued, when voltages increase, the amount of insulation for encapsulation also will have to increase. This increased insulation will increase weight and reduce system reliability. Therefore, non-solid insulation media must be examined to satisfy future spacecraft power and voltage demands. In this report, we assess the suitability of liquid, space vacuum, and gas insulation for space power systems.

  2. High voltage capability electrical coils insulated with materials containing SF.sub.6 gas

    DOEpatents

    Lanoue, Thomas J.; Zeise, Clarence L.; Wagenaar, Loren; Westervelt, Dean C.

    1988-01-01

    A coil is made having a plurality of layers of adjacent metal conductor windings subject to voltage stress, where the windings have insulation therebetween containing a small number of minute disposed throughout its cross-section, where the voids are voids filled with SF.sub.6 gas to substitute for air or other gaseous materials in from about 60% to about 95% of the cross-sectional void volume in the insulation, thus incorporating an amount of SF.sub.6 gas in the cross-section of the insulation effective to substantially increase corona inception voltages.

  3. Surface dynamics of amorphous polymers used for high-voltage insulators.

    PubMed

    Shemella, Philip T; Laino, Teodoro; Fritz, Oliver; Curioni, Alessandro

    2011-11-24

    Amorphous siloxane polymers are the backbone of high-voltage insulation materials. The natural hydrophobicity of their surface is a necessary property for avoiding leakage currents and dielectric breakdown. As these surfaces are exposed to the environment, electrical discharges or strong mechanical impact can temporarily destroy their water-repellent properties. After such events, however, a self-healing process sets in and restores the original hydrophobicity within some hours. In the present study, we investigate possible mechanisms of this restoration process. Using large-scale, all-atom molecular dynamics simulations, we show that molecules on the material surface have augmented motion that allows them to rearrange with a net polarization. The overall surface region has a net orientation that contributes to hydrophobicity, and charged groups that are placed at the surface migrate inward, away from the vacuum interface and into the bulk-like region. Our simulations provide insight into the mechanisms for hydrophobic self-recovery that repair material strength and functionality and suggest material compositions for future high-voltage insulators. PMID:22026429

  4. Repeated Strike Process During Disconnector Operation in Ultra-High Voltage Gas-Insulated Switchgear

    NASA Astrophysics Data System (ADS)

    Guan, Yonggang; Cai, Yuanji; Chen, Weijiang; Liu, Weidong; Li, Zhibing; Yue, Gongchang; Zhang, Junmin

    2016-03-01

    Very fast transient over-voltage (VFTO), induced by disconnector operations in gas-insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the experimental results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO. supported in part by National Natural Science Foundation of China (No. 51277106) and in part by the National Basic Research Program of China (973 Program) (No. 2011CB209405)

  5. Understanding the self-healing hydrophobic recovery of high-voltage insulators.

    PubMed

    Shemella, Philip T; Laino, Teodoro; Fritz, Oliver; Curioni, Alessandro

    2012-06-21

    Amorphous siloxane polymers are designed to have high dielectric strength for use as high-voltage insulation materials. Surface hydrophobicity is essential and can be impaired by environmental, electrical, or mechanical factors, leading to leakage currents due to dielectric breakdown. Self-recovery is possible and is generally observed over a period of several hours. Using large-scale, all-atom molecular dynamics simulations, the surface wetting of water droplets on the polymer surface is simulated for various surface conditions, including oxidation and coating with small molecules, to understand the driving forces of the recovery process at the atomistic level, which is of primary importance for the developments of novel materials. In this work, we shed light onto the self-recovery mechanism and propose the use of low-molecular-weight (LMW) siloxane to accelerate the recovery of hydrophobicity. PMID:22624664

  6. Improvement in power frequency strength of high voltage insulation structures. Final report

    SciTech Connect

    Lanoue, T.J.

    1980-09-01

    The need is foreseen to improve the power frequency strength of multi-dielectric insulation structures compared to the lightning and switching impulse strength. A fundamental investigation of the reaction of complex insulation models to voltages from the lightning impulse range through the long time power frequency range has been conducted. The results of this investigation will make it possible to determine principles for improving the power frequency strengths. The improvement in the power frequency strength should then make it possible to design insulation systems with optimized insulation spaces which would have adequate margin for power frequency overvoltages and would be properly coordinated with the arresters. The project involved three main areas of investigation: a review of system overvoltages; insulation studies in oil, using small models and complex insulation modes; and insulation studies in SF/sub 6/ gas. The studies and experiments are described, and the results are itemized. It is recommended that future insulation studies in oil should include a thorough investigation to correlate impurity particle concentration, size, shape, and type (metallic, dielectric) commonly found in power apparatus with 60 Hz breakdown of ASTM-D1816 standard electrodes, and a fundamental investigation should be undertaken to sort out the role played by electrohydrodynamic liquid motion in the AC breakdown of simple non-uniform field gaps and oil-paper insulation models for very pure and contaminated oil.

  7. Evaluation of Silicone Rubber Insulators used in High-Voltage Transmission Lines

    NASA Astrophysics Data System (ADS)

    Ul-Hamid, Anwar; Soufi, Khaled Y.; Al-Hamoudi, Ibrahim

    2008-04-01

    Three long-rod silicone rubber composite insulators used in 230 kV power transmission lines were evaluated for aging affects. The insulators were obtained from various outdoor desert locations within Saudi Arabia where they had been in service for 6 years. Surface degradation associated with the aging process was analyzed by using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infra-Red Spectroscopy (FTIR), and Electron Spectroscopy for Chemical Analysis (ESCA). Electrical performance of insulators was evaluated by Rapid Flashover Voltage Tests (RFVT) and Pollution Severity Measurement Tests. Depending on their locations of service, the samples exhibited various types of pollutants at their surfaces. The analysis indicated that the insulator material showed localized surface degradation while there was no evidence of micro-cracking. Furthermore, it was noted that the electrical performance of the insulators was not significantly affected by exposure during the in-service period.

  8. Design of load-to-failure tests of high-voltage insulation breaks for ITER's cryogenic network

    NASA Astrophysics Data System (ADS)

    Langeslag, S. A. E.; Rodriguez Castro, E.; Aviles Santillana, I.; Sgobba, S.; Foussat, A.

    2015-12-01

    The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound with so-called cable-in-conduit conductors. The concept of the cable-in-conduit conductor is based on a direct cooling principle, by supercritical helium, flowing through the central region of the conductor, in close contact with the superconducting strands. Consequently, a direct connection exists between the electrically grounded helium coolant supply line and the highly energised magnet windings. Various insulated regions, constructed out of high-voltage insulation breaks, are put in place to isolate sectors with different electrical potential. In addition to high voltages and significant internal helium pressure, the insulation breaks will experience various mechanical forces resulting from differential thermal contraction phenomena and electro-magnetic loads. Special test equipment was designed, prepared and employed to assess the mechanical reliability of the insulation breaks. A binary test setup is proposed, where mechanical failure is assumed when leak rate of gaseous helium exceeds 10-9·Pa·m3/s. The test consists of a load-to-failure insulation break charging, in tension, while immersed in liquid nitrogen at the temperature of 77 K. Leak tightness during the test is monitored by measuring the leak rate of the gaseous helium, directly surrounding the insulation break, with respect to the existing vacuum inside the insulation break. The experimental setup is proven effective, and various insulation breaks performed beyond expectations.

  9. Photoconductivity of high voltage space insulating materials: Measurements with metal electrodes

    NASA Technical Reports Server (NTRS)

    Coffey, H. T.; Nanevicz, J. E.

    1975-01-01

    The electrical conductivities of high voltage insulating materials were measured in the dark and under various intensities of illumination. The materials investigated included FEP Teflon, Kapton-H, fused quartz, and parylene. Conductivities were determined as functions of temperature between 22 and 100 C and light intensity between 0 and 2.5 kW/m2. The thickness dependence of the conductivity was determined for Teflon and Kapton, and the influence of spectral wavelengths on the conductivity was determined in several cases. All measurements were made in a vacuum to simulate a space environment, and all samples had metallic electrodes. The conductivity of Kapton was permanently increased by exposure to light; changes as great as five orders of magnitude were observed after six hours of illumination.

  10. Improved design of a high-voltage vacuum-insulator interface

    NASA Astrophysics Data System (ADS)

    Stygar, W. A.; Lott, J. A.; Wagoner, T. C.; Anaya, V.; Harjes, H. C.; Ives, H. C.; Wallace, Z. R.; Mowrer, G. R.; Shoup, R. W.; Corley, J. P.; Anderson, R. A.; Vogtlin, G. E.; Savage, M. E.; Elizondo, J. M.; Stoltzfus, B. S.; Andercyk, D. M.; Fehl, D. L.; Jaramillo, T. F.; Johnson, D. L.; McDaniel, D. H.; Muirhead, D. A.; Radman, J. M.; Ramirez, J. J.; Ramirez, L. E.; Spielman, R. B.; Struve, K. W.; Walsh, D. E.; Walsh, E. D.; Walsh, M. D.

    2005-05-01

    We have conducted a series of experiments designed to measure the flashover strength of various azimuthally symmetric 45° vacuum-insulator configurations. The principal objective of the experiments was to identify a configuration with a flashover strength greater than that of the standard design, which consists of a 45° polymethyl-methacrylate (PMMA) insulator between flat electrodes. The thickness d and circumference C of the insulators tested were held constant at 4.318 and 95.74 cm, respectively. The peak voltage applied to the insulators ranged from 0.8 to 2.2 MV. The rise time of the voltage pulse was 40 60 ns; the effective pulse width [as defined in Phys. Rev. ST Accel. Beams 7, 070401 (2004), PRABFM, 1098-4402, 10.1103/PhysRevSTAB.7.070401] was on the order of 10 ns. Experiments conducted with flat aluminum electrodes demonstrate that the flashover strength of a crosslinked polystyrene (Rexolite) insulator is (18±7)% higher than that of PMMA. Experiments conducted with a Rexolite insulator and an anode plug, i.e., an extension of the anode into the insulator, demonstrate that a plug can increase the flashover strength by an additional (44±11)%. The results are consistent with the Anderson model of anode-initiated flashover, and confirm previous measurements. It appears that a Rexolite insulator with an anode plug can, in principle, increase the peak electromagnetic power that can be transmitted across a vacuum interface by a factor of [(1.18)(1.44)]2=2.9 over that which can be achieved with the standard design.

  11. Ultra-High Voltage 4H-SiC Bi-Directional Insulated Gate Bipolar Transistors

    NASA Astrophysics Data System (ADS)

    Chowdhury, Sauvik

    4H- Silicon Carbide (4H-SiC) is an attractive material for power semiconductor devices due to its large bandgap, high critical electric field and high thermal conductivity compared to Silicon (Si). For ultra-high voltage applications (BV > 10 kV), 4H-SiC Insulated Gate Bipolar Transistors (IGBTs) are favored over unipolar transistors due to lower conduction losses. With improvements in SiC materials and processing technology, promising results have been demonstrated in the area of conventional unidirectional 4H-SiC IGBTs, with breakdown voltage ratings up to 27 kV. This research presents the experimental demonstration of the world's first high voltage bi-directional power transistors in 4H-SiC. Traditionally, four (two IGBTs and two diodes) or two (two reverse blocking IGBTs) semiconductor devices are necessary to yield a bidirectional switch. With a monolithically integrated bidirectional switch as presented here, the number of semiconductor devices is reduced to only one, which results in increased reliability and reduced cost of the overall system. Additionally, by using the unique dual gate operation of BD-IGBTs, switching losses can be reduced to a small fraction of that in conventional IGBTs, resulting in increased efficiency. First, the performance limits of SiC IGBTs are calculated by using analytical methods. The performance benefits of SiC IGBTs over SiC unipolar devices and Si IGBTs are quantified. Numerical simulations are used to optimize the unit cell and edge termination structures for a 15 kV SiC BD-IGBT. The effect of different device parameters on BD-IGBT static and switching performance are quantified. Second, the process technology necessary for the fabrication of high voltage SiC BD-IGBTs is optimized. The effect of different process steps on parameters such as breakdown voltage, carrier lifetime, gate oxide reliability, SiO2-SiC interface charge density is quantified. A carrier lifetime enhancement process has been optimized for lightly doped

  12. A Novel Electrical Insulating Material for 275 kV High-Voltage HTS Cable with Low Dielectric Loss

    NASA Astrophysics Data System (ADS)

    Hayakawa, N.; Nishimachi, S.; Maruyama, O.; Ohkuma, T.; Liu, J.; Yagi, M.

    2014-05-01

    In the case of high temperature superconducting (HTS) power transmission cables at high voltage operation, the electrical insulation technique in consideration of the dielectric loss reduction becomes crucial. In this paper, we focused on a Tyvek/polyethylene (PE) sheet, instead of the conventional polypropylene laminated paper (PPLP). We obtained the dielectric characteristics (epsilonr, tanδ) and partial discharge inception strength (PDIE) of PPLP, Tyvek and Tyvek/PE. We pointed out that the dielectric loss of 275 kV HTS cable with Tyvek/PE insulation will be reduced to 21 % of that with PPLP, and the total electrical loss including the AC loss will be reduced to 41 %.

  13. Development of polymer insulators for electrical and high-voltage power lines with the application of radiation-chemical technology

    SciTech Connect

    Kuznetsov, A.V.; Aleksandrov, G.N.; Ivanov, V.S.

    1993-12-31

    In the field of power engineering the problem of replacing traditional high-voltage porcelain and glass insulators by polymer insulators is being investigated. Polymers are desired which are relatively cheap and easy to process by molding. A copolymer of ethylene and vinyl acetate (EVA) filled aluminium hydroxide satisfys the requirements. In order to increase the heat stability of EVA, radiation-chemical technology was used in the present work. A pilot plant with a cobalt 60 radionuclide source was used as the source of ionizing radiation. The process of cross-linking EVA is described.

  14. Analysis of the possibilities of using dielectric foam in the construction of composite high voltage post-insulators

    NASA Astrophysics Data System (ADS)

    Mączka, T.; Paściak, G.; Jarski, A.; Piątek, M.

    2016-02-01

    This paper presents the construction and basic performance parameters of the innovative tubular construction of high voltage composite insulator filled with the lightweight foamed electroinsulating material. The possibility of using of the commercially available expanding foams for preparing the lightweight foamed dielectric materials was analysed. The expanding foams of silicone RTV and compositions based on epoxy resin and LSR silicone were taken into account. The lightweight foamed dielectric materials were prepared according to the own foaming technology. In this work the experimental results on the use of the selected foams for the preparing of the lightweight filling materials to the tubular structure of composite insulator of 110 kV are presented.

  15. Performance of ethylene-propylene rubber insulation in medium and high voltage power cable

    SciTech Connect

    Brown, M.

    1983-02-01

    A new class of EPR insulations having significantly improved electrical loss properties is described. These elastomeric insulations are compared in a number of key properties vs. XLPE which are believed significant in certain failure modes of power cables. Laboratory studies have shown that this new class of EPR's is extremely resistant to the initiation and growth of water and electrical trees. Data from the AEIC Accelerated Water/Electrochemical Tree Test are presented for high molecular weight thermoplastic PE, XLPE and EPR. In this test EPR shows a significant improvement in performance vs. PE and XLPE which is particularly evident in the high temperature (high current load) test mode.

  16. Modeling of nonlinearities in the capacitance-voltage characteristics of high-k metal-insulator-metal capacitors

    NASA Astrophysics Data System (ADS)

    Gonon, P.; Vallée, C.

    2007-04-01

    Metal-insulator-metal capacitors using high-k oxides are known to display nonlinear capacitance-voltage (C-V) characteristics. In the present work it is proposed that such nonlinearities arise from an electrode polarization mechanism. By considering a field activated hopping conduction in the bulk (related to oxygen vacancies), a simple analytical expression is derived which relates the capacitance to the applied bias. The model is able to predict voltage coefficients of capacitance and is found to be in good agreement with experimental C-V.

  17. Current collection from the space plasma through defects in high voltage solar array insulation. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Stillwell, R. P.

    1983-01-01

    For spacecraft operation in the near Earth environment, solar cell arrays constitute the major source of reliable long term power. Optimization of mass and power efficiency results in a general requirement for high voltage solar arrays. The space plasma environment, though, can result in large currents being collected by exposed solar cells. The solution of a protective covering of transparent insulation is not a complete solution, inasmuch as defects in the insulation result in anomalously large currents being collected through the defects. Tests simulating the electron collection from small defects in an insulation have shown that there are two major collection modes. The first mode involves current enhancement by means of a surface phenomenon involving the surrounding insulator. In the second mode the current collection is enhanced by vaporization and ionization of the insulators materials, in addition to the surface enhancement of the first mode. A model for the electron collection is the surface enhanced collection mode was developed. The model relates the secondary electron emission yield to the electron collection. It correctly predicts the qualitative effects of hole size, sample temperature and roughening of sample surface. The theory was also shown to predict electron collection within a factor of two for the polymers teflon and polyimide.

  18. Multilayer High-Gradient Insulators

    SciTech Connect

    Harris, J R; Anaya, R M; Blackfield, D; Chen, Y -; Falabella, S; Hawkins, S; Holmes, C; Paul, A C; Sampayan, S; Sanders, D M; Watson, J A; Caporaso, G J; Krogh, M

    2006-11-15

    High voltage systems operated in vacuum require insulating materials to maintain spacing between conductors held at different potentials, and may be used to maintain a nonconductive vacuum boundary. Traditional vacuum insulators generally consist of a single material, but insulating structures composed of alternating layers of dielectric and metal can also be built. These ''High-Gradient Insulators'' have been experimentally shown to withstand higher voltage gradients than comparable conventional insulators. As a result, they have application to a wide range of high-voltage vacuum systems where compact size is important. This paper describes ongoing research on these structures, as well as the current theoretical understanding driving this work.

  19. Long term experience with semi-conductive glaze high voltage post insulators

    SciTech Connect

    Baker, A.C.; Maney, J.W.; Szilagyi, Z. )

    1990-01-01

    Insulators using semi-conductive glaze have long been known for their superior contamination performance. Early glazes for this type however were not stable and successful use of semi-conductive glazed porcelain insulators was delayed many years until tin-antimony oxide glazes were developed. Service experience of eighteen years is now available for line and station post insulators with this type of glaze. Based on this experience, the aging characteristics of tin-antimony oxide semi-conductive glazes are described and quantified. Several different applications of these insulators are also described.

  20. Control of Cable Insulation Quality by Changing of Electrical Capacitance Per Unit During High Voltage Testing

    NASA Astrophysics Data System (ADS)

    Starikova, N. S.; Redko, V. V.; Vavilova, G. V.

    2016-01-01

    The paper describes the complex method of insulation quality control. It was found that electrical contact between bead chain electrodes and insulation surface can be provided by surface discharges along the entire length of the controlled zone. The pattern of electromagnetic field was developed by using Comsol Myltiphysics software.

  1. Investigations of the electrical breakdown properties of insulator materials used in high voltage vacuum diodes

    SciTech Connect

    Shurter, R.P.; Carlson, R.L.; Melton, J.G.

    1993-08-01

    The Injector for the proposed Dual-Axis Radiographic Hydrodynamic Testing (DARHT) Facility at Los Alamos utilizes a monolithic insulator deployed in a radial configuration. The 1.83-m-diam {times} 25.4-cm-thick insulator with embedded grading rings separates the output oil transmission line from the vacuum vessel that contains the re-entrant anode and cathode assemblies. Although much work has been done by the pulse power community in studying surface flash-over of insulating materials used in both axial and radial configurations, dendrite growth at the roots of grading rings embedded in materials suitable for very large insulators is less well characterized. Degradation of several acrylic insulators has been observed in the form of dendrites growing at the roots of the grading rings for large numbers (100`s) of pulses on the prototype DARHT Injector and other machines using similar radial geometries. In a few cases, these dendrites have led to catastrophic bulk breakdown of the acrylic between two grading rings making the insulator a costly loss. Insulating materials under investigation are acrylic (Lucite), epoxy (Furane), and cross-linked polystyrene (Rexolite); each of these materials has its own particular mechanical and electrical merits. All of these materials have been cast and machined into the required large size for the Injector. Test methods and the results of investigations into the breakdown strength of various interface geometries and the susceptibility of these materials to dendrite growth are reported.

  2. Energy spectrum of corona impulses generated from insulated wires under high a.c. voltages

    NASA Technical Reports Server (NTRS)

    Doreswamy, C. V.; Padiyar, K. R.; Crowell, C. S.

    1978-01-01

    This paper suggests methods for calculating spectral energy densities of corona impulses generated from insulated conductors. The calculation is based on the data obtained from the measurement of corona pulse waveforms, repetition rates and relevant statistical properties of corona impulses.

  3. The influence of macrofouling on two polymers used as insulation on submarine high voltage cables in Cozumel, Mexico

    SciTech Connect

    Ramirez-Delgado, R.; Valero-Huerta, M.A.

    1995-11-01

    Macrofouling is a major source of problems causing poor power plant availability and efficiency. A variety of macrofouling control technologies has been developed for use at power plants, however, only one control technology has been designed to protect submarine cables used for electric transmission. The selection of materials possessing antifouling properties is the method used to control the growth of marine fouling organisms. Such methodology is applied in this study with the purpose of evaluating the behavior of two polymers. This practice will permit choosing the polymer that presents the better antifouling properties. In this study are presented the results obtained from the tension and elongation tests accomplished on two kinds of plastic materials: high density polyethylene (PE) and polyvinyl chloride (PVC), both of which were exposed to bio-degradation during 106 and 162 days, at different depths in the Caribbean Sea. The proven materials will be used as electrical insulation in submarine cables of high voltage: 115 kV.

  4. Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

    PubMed Central

    Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

    2015-01-01

    Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

  5. Application of HFCT and UHF sensors in on-line partial discharge measurements for insulation diagnosis of high voltage equipment.

    PubMed

    Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

    2015-01-01

    Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

  6. Application of infrared spectroscopy to monitoring gas insulated high-voltage equipment: electrode material-dependent SF(6) decomposition.

    PubMed

    Kurte, R; Beyer, C; Heise, H M; Klockow, D

    2002-08-01

    Sulfur hexafluoride is a chemically inert gas which is used in gas insulated substations (GIS) and other high-voltage equipment, leading to a significant enhancement of apparatus lifetime and reductions in installation size and maintenance requirements compared to conventional air insulated substations. However, component failures due to aging of the gas through electrical discharges may occur, and on-site monitoring for risk assessment is needed. Infrared spectroscopy was used for the analysis of gaseous by-products generated from electrical discharges in sulfur hexafluoride gas. An infrared monitoring system was developed using a micro-cell coupled to an FTIR spectrometer by silver halide fibers. Partial least-squares calibration was applied by using a limited number of optimally selected spectral variables. Emphasis was placed on the determination of main decomposition products, such as SOF(2), SOF(4), and SO(2)F(2). Besides the different electrical conditions, the material of the plane counter electrode of the discharge chamber was also varied between silver, aluminum, copper, tungsten, or tungsten/copper alloy. For the spark experiments the point electrode was the same material as chosen for the plane electrode, whereas for partial discharges a stainless steel needle was employed. Complementary investigations on the chemical composition within the solid counter electrode material by secondary neutral mass spectrometry (SNMS) were also carried out. Under sparking conditions, the electrode material plays an important role in the decomposition rates of the gas-phase, but no relevant material dependence could be observed under partial discharge conditions. PMID:12185577

  7. The role of carbon contamination in voltage linearity and leakage current in high-k metal-insulator-metal capacitors

    NASA Astrophysics Data System (ADS)

    Miao, Bing; Mahapatra, Rajat; Wright, Nick; Horsfall, Alton

    2008-09-01

    The effect of carbon contamination on the electrical properties of metal-insulator-metal (MIM) capacitor using HfO2 dielectric has been reported. The HfO2 film with lower carbon contamination shows an overall high performance, such as a higher capacitance density of 5.21 fF/μm2, a lower leakage current of 1.3×10-7 A/cm2 at 1 V, lower-voltage coefficients of capacitance, and better frequency and temperature dispersion properties compared with the capacitor of theHfO2 film with higher carbon contamination. The calculated ac barrier heights by electrode polarization model from capacitance-voltage (C-V) characteristics are 0.58 eV for the HfO2 film with high carbon contamination and 0.95 eV for the HfO2 film with negligible carbon contamination. The dc barrier heights extracted from current-voltage (I-V) characteristics are 0.26 eV for the HfO2 film with high carbon contamination and 1.1 eV for the HfO2 film with negligible carbon contamination. All of these experimental results exhibit that the increase in defect density in HfO2 films generated from carbon impurities results in the degradation of barrier heights and poor performance of the MIM capacitor. It is important to point out that, during the fabrication process of the MIM capacitor, the carbon contamination must be minimized.

  8. Mastering electrical faults in high voltage stations insulated using SF6

    NASA Astrophysics Data System (ADS)

    Bernard, G.

    1981-12-01

    Faults occurring in electricity substations were analyzed. While most faults appear during the first few months of operation and can be attributed to running-in problems, or are due to human error, the possibility of arc discharges remains. These discharges cause a sudden increase of heat and pressure in installations and can provoke chemical reactions with insulating materials. Guidelines for selecting materials and designing systems to limit arc induced damage are presented.

  9. Low-voltage organic field-effect transistors based on novel high-κ organometallic lanthanide complex for gate insulating materials

    SciTech Connect

    Liu, Qi; Li, Yi; Zhang, Yang; Song, You E-mail: yli@nju.edu.cn Wang, Xizhang E-mail: yli@nju.edu.cn Hu, Zheng; Sun, Huabin; Li, Yun E-mail: yli@nju.edu.cn Shi, Yi

    2014-08-15

    A novel high-κ organometallic lanthanide complex, Eu(tta){sub 3}L (tta=2-thenoyltrifluoroacetonate, L = 4,5-pinene bipyridine), is used as gate insulating material to fabricate low-voltage pentacene field-effect transistors (FETs). The optimized gate insulator exhibits the excellent properties such as low leakage current density, low surface roughness, and high dielectric constant. When operated under a low voltage of −5 V, the pentacene FET devices show the attractive electrical performance, e.g. carrier mobility (μ{sub FET}) of 0.17 cm{sup 2} V{sup −1} s{sup −1}, threshold voltage (V{sub th}) of −0.9 V, on/off current ratio of 5 × 10{sup 3}, and subthreshold slope (SS) of 1.0 V dec{sup −1}, which is much better than that of devices obtained on conventional 300 nm SiO{sub 2} substrate (0.13 cm{sup 2} V{sup −1} s{sup −1}, −7.3 V and 3.1 V dec{sup −1} for μ{sub FET}, V{sub th} and SS value when operated at −30 V). These results indicate that this kind of high-κ organometallic lanthanide complex becomes a promising candidate as gate insulator for low-voltage organic FETs.

  10. A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance.

    PubMed

    Wen, Tao; Zhang, Qiaogen; Zhang, Lingli; Zhao, Junping; Liu, Xuandong; Li, Xiaoang; Guo, Can; You, Haoyang; Chen, Weijiang; Yin, Yu; Shi, Weidong

    2016-03-01

    At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time T(f) ≥ 2.5 μs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of T(f) exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10,000 pF. PMID:27036815

  11. A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance

    NASA Astrophysics Data System (ADS)

    Wen, Tao; Zhang, Qiaogen; Zhang, Lingli; Zhao, Junping; Liu, Xuandong; Li, Xiaoang; Guo, Can; You, Haoyang; Chen, Weijiang; Yin, Yu; Shi, Weidong

    2016-03-01

    At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time Tf ≥ 2.5 μs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of Tf exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10 000 pF.

  12. Assessment of the risk of failure of high voltage substations due to environmental conditions and pollution on insulators.

    PubMed

    Castillo Sierra, Rafael; Oviedo-Trespalacios, Oscar; Candelo, John E; Soto, Jose D

    2015-07-01

    Pollution on electrical insulators is one of the greatest causes of failure of substations subjected to high levels of salinity and environmental pollution. Considering leakage current as the main indicator of pollution on insulators, this paper focuses on establishing the effect of the environmental conditions on the risk of failure due to pollution on insulators and determining the significant change in the magnitude of the pollution on the insulators during dry and humid periods. Hierarchical segmentation analysis was used to establish the effect of environmental conditions on the risk of failure due to pollution on insulators. The Kruskal-Wallis test was utilized to determine the significant changes in the magnitude of the pollution due to climate periods. An important result was the discovery that leakage current was more common on insulators during dry periods than humid ones. There was also a higher risk of failure due to pollution during dry periods. During the humid period, various temperatures and wind directions produced a small change in the risk of failure. As a technical result, operators of electrical substations can now identify the cause of an increase in risk of failure due to pollution in the area. The research provides a contribution towards the behaviour of the leakage current under conditions similar to those of the Colombian Caribbean coast and how they affect the risk of failure of the substation due to pollution. PMID:25634366

  13. Experimental evidence for the role of electrodes and oxygen vacancies in voltage nonlinearities observed in high-k metal-insulator-metal capacitors

    NASA Astrophysics Data System (ADS)

    El Kamel, F.; Gonon, P.; Vallée, C.

    2007-10-01

    This work reports on voltage nonlinearities in metal-insulator-metal (MIM) capacitors using amorphous barium titanate (a-BaTiO3) thin films. It is experimentally demonstrated that voltage nonlinearity is related to the formation of a double layer at electrodes (electrode polarization mechanism). The magnitude of nonlinearities is shown to be controlled by the nature of the metal contacts (Al, Cu, Au, and Ag), as well as by the presence of oxygen during film deposition. It is thought that oxygen vacancies are the defects responsible for the nonlinear character of high-k oxide-based MIM capacitors.

  14. AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors with reduced leakage current and enhanced breakdown voltage using aluminum ion implantation

    NASA Astrophysics Data System (ADS)

    Sun, Shichuang; Fu, Kai; Yu, Guohao; Zhang, Zhili; Song, Liang; Deng, Xuguang; Qi, Zhiqiang; Li, Shuiming; Sun, Qian; Cai, Yong; Dai, Jiangnan; Chen, Changqing; Zhang, Baoshun

    2016-01-01

    This letter has studied the performance of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors on silicon substrate with GaN buffer treated by aluminum ion implantation for insulating followed by a channel regrown by metal-organic chemical vapor deposition. For samples with Al ion implantation of multiple energies of 140 keV (dose: 1.4 × 1014 cm-2) and 90 keV (dose: 1 × 1014 cm-2), the OFF-state leakage current is decreased by more than 3 orders and the breakdown voltage is enhanced by nearly 6 times compared to the samples without Al ion implantation. Besides, little degradation of electrical properties of the 2D electron gas channel is observed where the maximum drain current IDSmax at a gate voltage of 3 V was 701 mA/mm and the maximum transconductance gmmax was 83 mS/mm.

  15. System for increasing corona inception voltage of insulating oils

    DOEpatents

    Rohwein, Gerald J.

    1998-01-01

    The Corona Inception Voltage of insulating oils is increased by repetitive cycles of prestressing the oil with a voltage greater than the corona inception voltage, and either simultaneously or serially removing byproducts of corona by evacuation and heating the oil.

  16. High voltage isolation transformer

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C. H.; Ruitberg, A. P. (Inventor)

    1985-01-01

    A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.

  17. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  18. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

    1998-10-13

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

  19. Assessment of basic contamination withstand voltage characteristics of polymer insulators

    SciTech Connect

    Matsuoka, R.; Shinokubo, H.; Kondo, K.; Mizuno, Y.; Naito, K.; Fujimura, T.; Terada, T.

    1996-10-01

    An artificial contamination method for hydrophobic polymer insulators was newly developed, which can provide a uniform contaminant layer similar to the natural one neither by damaging the polymer surface nor by adding any chemical agent to the conventional contamination slurry. Using this method, basic contamination withstand voltage characteristics of polymer insulators were investigated comparing with those of porcelain insulators. The results show that although hydrophobic withstand voltage characteristics critical reduction of withstand voltage occurs sometimes under rapid and heavy wetting and contamination conditions.

  20. Determination of threshold and maximum operating electric stresses for selected high voltage insulations: Investigation of aged polymeric dielectric cable. Final report

    SciTech Connect

    Eager, G.S. Jr.; Seman, G.W.; Fryszczyn, B.

    1995-11-01

    Based on the successful completion of the extensive research project DOE/ET/29303-1 February 1982 to develop a new method for the determination of threshold voltage in XLPE and EPR insulated cables, tests were initiated to establish the maximum safe operating voltage stresses of crosslinked polyethylene insulated cables that become wet when they operate in a moist environment. The present report covers the measurement of the threshold voltage, the a.c. breakdown voltage and the impulse breakdown voltage of XLPE cable after undergoing accelerated laboratory aging in water. Model and 15 kV XLPE cables were manufactured in commercial equipment using state-of-the-art semiconducting shields and XLPE insulation. The threshold voltage, a.c. voltage breakdown and impulse voltage breakdown of the model cables were determined before aging, after aging one week and after aging 26 weeks. The model cable, following 26 weeks aging, was dried by passing dry gas through the conductor interstices which removed moisture from the cable. The threshold voltage, the a.c. voltage breakdown and the impulse voltage breakdown of the XLPE model cable after drying was measured.

  1. Epitaxial growth and characterization of thick multi-layer 4H-SiC for very high-voltage insulated gate bipolar transistors

    NASA Astrophysics Data System (ADS)

    Miyazawa, Tetsuya; Nakayama, Koji; Tanaka, Atsushi; Asano, Katsunori; Ji, Shi-yang; Kojima, Kazutoshi; Ishida, Yuuki; Tsuchida, Hidekazu

    2015-08-01

    Techniques to fabricate thick multi-layer 4H-SiC epitaxial wafers were studied for very high-voltage p- and n-channel insulated gate bipolar transistors (IGBTs). Multi-layer epitaxial growth, including a thick p- drift layer (˜180 μm), was performed on a 4H-SiC n+ substrate to form a p-IGBT structure. For an n-IGBT structure, an inverted growth process was employed, in which a thick n- drift layer (˜180 μm) and a thick p++ injector layer (>55 μm) were epitaxially grown. The epitaxial growth conditions were modified to attain a low defect density, a low doping concentration, and a long carrier lifetime in the drift layers. Reduction of the forward voltage drop was attempted by using carrier lifetime enhancement processes, specifically, carbon ion implantation/annealing and thermal oxidation/annealing or hydrogen annealing. Simple PiN diodes were fabricated to demonstrate the effective conductivity modulation in the thick drift layers. The forward voltage drops of the PiN diodes with the p- and n-IGBT structures promise to obtain the extremely low-loss and very high-voltage IGBTs. The change in wafer shape during the processing of the very thick multi-layer 4H-SiC is also discussed.

  2. Electrode oxygen-affinity influence on voltage nonlinearities in high-k metal-insulator-metal capacitors

    NASA Astrophysics Data System (ADS)

    Vallée, C.; Gonon, P.; Jorel, C.; El Kamel, F.

    2010-06-01

    This work highlights the influence of the oxygen affinity of the metal electrodes used in high-k metal-insulator-metal capacitors. Several metallic electrodes are tested in order to investigate the role of the metal work function, and the role of the electrode oxygen-affinity in nonlinear behavior of HfO2 and BaTiO3 capacitors. It is shown that the magnitude of the quadratic coefficient of nonlinearity is better explained by the electrode oxygen-affinity rather than by its work function. It is thought that electrode oxidation increases the number of oxygen vacancies at the electrode/dielectric interface, and so increases the magnitude of nonlinearity.

  3. Low voltage, high performance inkjet printed carbon nanotube transistors with solution processed ZrO2 gate insulator

    NASA Astrophysics Data System (ADS)

    Kim, Bongjun; Jang, Seonpil; Prabhumirashi, Pradyumna L.; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2013-08-01

    High-performance single-walled carbon nanotube (SWCNT) thin-film transistors are fabricated by single-pass inkjet printing of SWCNTs on high-κ solution-processed ZrO2 gate dielectric. We demonstrate that an ultraviolet ozone treatment of the ZrO2 substrate is critical in achieving a uniform dispersion of sorted SWCNTs in the semiconducting channel. The resulting devices exhibit excellent performance with mobility and on/off current ratio exceeding 30 cm2 V-1 s-1 and 105, respectively, at low operating voltages (<5 V). The single-pass inkjet printing process demonstrated in this letter shows great promise as a reliable and scalable method for SWCNT based high performance electronics.

  4. HIGH VOLTAGE, HIGH CURRENT SPARK GAP SWITCH

    DOEpatents

    Dike, R.S.; Lier, D.W.; Schofield, A.E.; Tuck, J.L.

    1962-04-17

    A high voltage and current spark gap switch comprising two main electrodes insulatingly supported in opposed spaced relationship and a middle electrode supported medially between the main electrodes and symmetrically about the median line of the main electrodes is described. The middle electrode has a perforation aligned with the median line and an irradiation electrode insulatingly supported in the body of the middle electrode normal to the median line and protruding into the perforation. (AEC)

  5. High voltage breakdown studies of sol-gel MgO-ZrO 2 insulation coatings under various pressures at 298 K and 77 K

    NASA Astrophysics Data System (ADS)

    Cakiroglu, O.; Arda, L.; Hascicek, Y. S.

    2005-06-01

    High voltage breakdown (HV bd) tests were performed to investigate electrical properties of high temperature MgO-ZrO 2 insulation coatings on long-length stainless steel (SS) tapes under various pressures at room temperature (298 K) and liquid nitrogen temperature (77 K) for applications of HTS/LTS coils and magnets. After solutions were prepared from Mg and Zr based precursors, solvent and chelating agent, the coating were fabricated on SS substrates using reel-to-reel sol-gel technique. Coating thicknesses for 4, 8, and 9 dippings were about 7, 12, and 13 μm, respectively, and thickness of epoxy-impregnated samples (stycast 2850 FT/24 LV) were measured to be 32 μm. The pressure from 0 GPa to 0.54 GPa was applied on to test couples, the stycast thicknesses between the layers were varied 32-20 μm. Thickness of the coatings and epoxy-impregnated using stycast were determined by using environmental scanning electron microscopy (ESEM). The resistance, capacitance, and HV bd of the samples were measured by using standard machines HP 439 a high resistance meter, 161 analog digital capacitance meter and model 200-02R high voltage power supply, respectively. Electric strength and dielectric constant were calculated at 298 and 77 K under various pressures. The high HV bd, and electric strength values of the samples were 2.84 kV and 45.91 kV/mm, respectively. ESEM observation revealed that arcing spots in the insulation coatings become larger and deeper for higher HV bd’s.

  6. System for increasing corona inception voltage of insulating oils

    DOEpatents

    Rohwein, G.J.

    1998-05-19

    The Corona Inception Voltage of insulating oils is increased by repetitive cycles of prestressing the oil with a voltage greater than the corona inception voltage, and either simultaneously or serially removing byproducts of corona by evacuation and heating the oil. 5 figs.

  7. High voltage solar array experiments

    NASA Technical Reports Server (NTRS)

    Kennerud, K. L.

    1974-01-01

    The interaction between the components of a high voltage solar array and a simulated space plasma is studied to obtain data for the design of a high voltage solar array capable of 15kW at 2 to 16kV. Testing was conducted in a vacuum chamber 1.5-m long by 1.5-m diameter having a plasma source which simulated the plasma conditions existing in earth orbit between 400 nautical miles and synchronous altitude. Test samples included solar array segments pinholes in insulation covering high voltage electrodes, and plain dielectric samples. Quantitative data are presented in the areas of plasma power losses, plasma and high voltage induced damage, and dielectric properties. Limitations of the investigation are described.

  8. Silicon-on-insulator-based high-voltage, high-temperature integrated circuit gate driver for silicon carbide-based power field effect transistors

    SciTech Connect

    Tolbert, Leon M; Huque, Mohammad A; Blalock, Benjamin J; Islam, Syed K

    2010-01-01

    Silicon carbide (SiC)-based field effect transistors (FETs) are gaining popularity as switching elements in power electronic circuits designed for high-temperature environments like hybrid electric vehicle, aircraft, well logging, geothermal power generation etc. Like any other power switches, SiC-based power devices also need gate driver circuits to interface them with the logic units. The placement of the gate driver circuit next to the power switch is optimal for minimising system complexity. Successful operation of the gate driver circuit in a harsh environment, especially with minimal or no heat sink and without liquid cooling, can increase the power-to-volume ratio as well as the power-to-weight ratio for power conversion modules such as a DC-DC converter, inverter etc. A silicon-on-insulator (SOI)-based high-voltage, high-temperature integrated circuit (IC) gate driver for SiC power FETs has been designed and fabricated using a commercially available 0.8--m, 2-poly and 3-metal bipolar-complementary metal oxide semiconductor (CMOS)-double diffused metal oxide semiconductor (DMOS) process. The prototype circuit-s maximum gate drive supply can be 40-V with peak 2.3-A sourcing/sinking current driving capability. Owing to the wide driving range, this gate driver IC can be used to drive a wide variety of SiC FET switches (both normally OFF metal oxide semiconductor field effect transistor (MOSFET) and normally ON junction field effect transistor (JFET)). The switching frequency is 20-kHz and the duty cycle can be varied from 0 to 100-. The circuit has been successfully tested with SiC power MOSFETs and JFETs without any heat sink and cooling mechanism. During these tests, SiC switches were kept at room temperature and ambient temperature of the driver circuit was increased to 200-C. The circuit underwent numerous temperature cycles with negligible performance degradation.

  9. Analysis of high field effects on the steady-state current-voltage response of semi-insulating 4H-SiC for photoconductive switch applications

    SciTech Connect

    Tiskumara, R.; Joshi, R. P. Mauch, D.; Dickens, J. C.; Neuber, A. A.

    2015-09-07

    A model-based analysis of the steady-state, current-voltage response of semi-insulating 4H-SiC is carried out to probe the internal mechanisms, focusing on electric field driven effects. Relevant physical processes, such as multiple defects, repulsive potential barriers to electron trapping, band-to-trap impact ionization, and field-dependent detrapping, are comprehensively included. Results of our model match the available experimental data fairly well over orders of magnitude variation in the current density. A number of important parameters are also extracted in the process through comparisons with available data. Finally, based on our analysis, the possible presence of holes in the samples can be discounted up to applied fields as high as ∼275 kV/cm.

  10. High voltage RF feedthrough bushing

    DOEpatents

    Grotz, Glenn F.

    1984-01-01

    Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  11. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  12. HIGH VOLTAGE GENERATOR

    DOEpatents

    Zito, G.V.

    1959-04-21

    This patent relates to high voltage supply circuits adapted for providing operating voltages for GeigerMueller counter tubes, and is especially directed to an arrangement for maintaining uniform voltage under changing conditions of operation. In the usual power supply arrangement for counter tubes the counter voltage is taken from across the power supply output capacitor. If the count rate exceeds the current delivering capaciiy of the capacitor, the capacitor voltage will drop, decreasing the counter voltage. The present invention provides a multivibrator which has its output voltage controlled by a signal proportional to the counting rate. As the counting rate increases beyond the current delivering capacity of the capacitor, the rectified voltage output from the multivibrator is increased to maintain uniform counter voltage.

  13. Influence of fog parameters on withstand voltage of contaminated insulators

    SciTech Connect

    Naito, K.; Ito, M.; Katsukawa, H.; Kawaguchi, T.; Suzuki, Y.

    1983-03-01

    This paper describes the investigation results of fog parameters which affect the withstand voltage of contaminated insulators. As a result, the guideline is proposed on fog conditions such as density, droplet size distribution, temperature rise in the fog room, and so on, basing upon the comparison between natural and artificial fog conditions and the relation between fog condition and power-frequency withstand voltage.

  14. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2014-01-01

    Time dependence of absorption voltages (V(sub abs)) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on V(sub abs)), cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on V(sub abs)), are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks.

  15. High Voltage SPT Performance

    NASA Technical Reports Server (NTRS)

    Manzella, David; Jacobson, David; Jankovsky, Robert

    2001-01-01

    A 2.3 kW stationary plasma thruster designed to operate at high voltage was tested at discharge voltages between 300 and 1250 V. Discharge specific impulses between 1600 and 3700 sec were demonstrated with thrust between 40 and 145 mN. Test data indicated that discharge voltage can be optimized for maximum discharge efficiency. The optimum discharge voltage was between 500 and 700 V for the various anode mass flow rates considered. The effect of operating voltage on optimal magnet field strength was investigated. The effect of cathode flow rate on thruster efficiency was considered for an 800 V discharge.

  16. Suppression Effect and Mechanism of Platinum and Nitrogen-Containing Silane on the Tracking and Erosion of Silicone Rubber for High-Voltage Insulation.

    PubMed

    Chen, Wan Juan; Zeng, Xingrong; Lai, Xuejun; Li, Hongqiang; Fang, Wei Zhen; Hou, Fei

    2016-08-17

    How to effectively improve the tracking and erosion resistance of silicone rubber (SR) was an urgent topic in the field of high-voltage insulation. In this work, the tracking and erosion resistance of SR was significantly improved by incorporating platinum (Pt) catalyst and nitrogen-containing silane (NS). The suppression effect and mechanism of Pt/NS on tracking and erosion were studied by inclined plane (IP) test, thermogravimetry (TG), thermogravimetry-Fourier transform infrared spectrometry, laser Raman spectroscopy, and scanning electron microscopy. It revealed that when 1.4 phr of NS and 6.7 ppm of Pt were added, the tracking resistance of SR was improved from 2.5 to 4.5 kV level in the IP test, and the eroded mass was significantly reduced. This might be attributed to the synergistic effect of Pt/NS on silicone chains. At a high temperature produced by arc discharge, Pt/NS would catalyze radical cross-linking, meanwhile suppressing oxidation and depolymerization of silicone chains. Hence, a tightly cross-linked network was formed and protected inner materials from arc ablation. Moreover, carbon deposit during pyrolysis was suppressed by Pt/NS, which served as the secondary mechanism of tracking suppression. PMID:27462876

  17. HIGH VOLTAGE REGULATOR

    DOEpatents

    Wright, B.T.

    1959-06-01

    A high voltage regulator for use with calutrons is described which rapidly restores accelerating voltage after a sudden drop such as is caused by sparking. The rapid restoration characteristic prevents excessive contamination of lighter mass receiver pockets by the heavier mass portion of the beam. (T.R.H.)

  18. Experimental demonstration of an anode voltage sensor for high voltage IGBT over-voltage protection

    NASA Astrophysics Data System (ADS)

    Caramel, C.; Flores, D.; Hidalgo, S.; Legal, J.; Austin, P.; Imbernon, E.; Rebollo, J.; Sánchez, J. L.

    2010-11-01

    This paper deals with the design and fabrication of a monolithically integrated over-voltage sensor together with high voltage IGBTs. This solution will be of interest in harsh environment applications such as power modules for traction. First, the anode voltage sensor concept is introduced and an initial experimental validation on 600 V insulated gate bipolar transistor (IGBT) devices is provided. Then, guidelines for the design of a 3.3 kV IGBT including the proposed anode voltage sensor are pointed out together with its process fabrication. Finally, experimental results on fabricated 3.3 kV IGBTs are presented and compared with simulated expected behaviour.

  19. High voltage load resistor array

    DOEpatents

    Lehmann, Monty Ray

    2005-01-18

    A high voltage resistor comprising an array of a plurality of parallel electrically connected resistor elements each containing a resistive solution, attached at each end thereof to an end plate, and about the circumference of each of the end plates, a corona reduction ring. Each of the resistor elements comprises an insulating tube having an electrode inserted into each end thereof and held in position by one or more hose clamps about the outer periphery of the insulating tube. According to a preferred embodiment, the electrode is fabricated from stainless steel and has a mushroom shape at one end, that inserted into the tube, and a flat end for engagement with the end plates that provides connection of the resistor array and with a load.

  20. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E.; Wojtczuk, Steve; Jacobson, Gerard F.; Hagans, Karla G.

    2001-01-01

    An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat top laser beam profile is illuminated upon the array to produce electrical current having high voltage. An essentially wireless system includes a laser energy source being fed through optic fiber and cast upon the photovoltaic cell array to prevent stray electrical signals prior to use of the current from the array. Direct bandgap, single crystal semiconductor materials, such as GaAs, are commonly used in the array. Useful applications of the system include locations where high voltages are provided to confined spaces such as in explosive detonation, accelerators, photo cathodes and medical appliances.

  1. Correlation of interface states/border traps and threshold voltage shift on AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

    SciTech Connect

    Wu, Tian-Li Groeseneken, Guido; Marcon, Denis; De Jaeger, Brice; Lin, H. C.; Franco, Jacopo; Stoffels, Steve; Van Hove, Marleen; Decoutere, Stefaan; Bakeroot, Benoit; Roelofs, Robin

    2015-08-31

    In this paper, three electrical techniques (frequency dependent conductance analysis, AC transconductance (AC-g{sub m}), and positive gate bias stress) were used to evaluate three different gate dielectrics (Plasma-Enhanced Atomic Layer Deposition Si{sub 3}N{sub 4}, Rapid Thermal Chemical Vapor Deposition Si{sub 3}N{sub 4}, and Atomic Layer Deposition (ALD) Al{sub 2}O{sub 3}) for AlGaN/GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors. From these measurements, the interface state density (D{sub it}), the amount of border traps, and the threshold voltage (V{sub TH}) shift during a positive gate bias stress can be obtained. The results show that the V{sub TH} shift during a positive gate bias stress is highly correlated to not only interface states but also border traps in the dielectric. A physical model is proposed describing that electrons can be trapped by both interface states and border traps. Therefore, in order to minimize the V{sub TH} shift during a positive gate bias stress, the gate dielectric needs to have a lower interface state density and less border traps. However, the results also show that the commonly used frequency dependent conductance analysis technique to extract D{sub it} needs to be cautiously used since the resulting value might be influenced by the border traps and, vice versa, i.e., the g{sub m} dispersion commonly attributed to border traps might be influenced by interface states.

  2. High voltage power supply

    NASA Technical Reports Server (NTRS)

    Ruitberg, A. P.; Young, K. M. (Inventor)

    1985-01-01

    A high voltage power supply is formed by three discrete circuits energized by a battery to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. In the first two circuits, the regulator stages are pulse width modulated and include adjustable ressistances for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance for varying the amplitude of a steady signal provided to a third oscillator stage. In the first circuit, the oscillator, formed by a constant current drive network and a tuned resonant network included a step up transformer, is coupled to a second step up transformer which, in turn, supplies an amplified sinusoidal signal to a parallel pair of complementary poled rectifying, voltage multiplier stages to generate the high output voltage.

  3. A computational study of flashover voltage of iced insulators

    SciTech Connect

    Sundarajan, R.

    1996-11-01

    In cold or mountainous regions, snow or ice, superimposed with contaminants covered on insulators cause flashover of insulators at nominal operating voltage. Laboratory simulation of icing performance of a set of insulators takes elaborate preparation. Additionally, there is a wide scattering of data due to the difference in the nature and quantity of ice and snow. Hence, it is desirable to develop a valid, realistic computer aided technique to study icing flashover. Presented in this paper are the results of an investigation of the flashover voltage of porcelain insulators under iced conditions using a contamination flashover model. The ice or snow is treated as a contaminant, the severity of which is represented in terms of the conductivity of the water melted from the ice or snow, and the thickness and the degree of the ice covering. Model results in good agreement with experimental data have been obtained. Both AC and DC insulators have been considered for this study. The results demonstrate the use of the model as a complement to experimental techniques to rank the icing performance of various HV outdoor insulators.

  4. Multilayer High-Gradient Insulators

    SciTech Connect

    Harris, J R

    2006-08-16

    Multilayer High-Gradient Insulators are vacuum insulating structures composed of thin, alternating layers of dielectric and metal. They are currently being developed for application to high-current accelerators and related pulsed power systems. This paper describes some of the High-Gradient Insulator research currently being conducted at Lawrence Livermore National Laboratory.

  5. High voltage pulse generator

    DOEpatents

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  6. High voltage distributed amplifier

    NASA Astrophysics Data System (ADS)

    Willems, D.; Bahl, I.; Wirsing, K.

    1991-12-01

    A high-voltage distributed amplifier implemented in GaAs MMIC technology has demonstrated good circuit performance over at least two octave bandwidth. This technique allows for very broadband amplifier operation with good efficiency in satellite, active-aperture radar, and battery-powered systems. Also, by increasing the number of FETs, the amplifier can be designed to match different voltage rails. The circuit does require a small amount of additional chip size over conventional distributed amplifiers but does not require power dividers or additional matching networks. This circuit configuration should find great use in broadband power amplifier design.

  7. Compact high voltage battery

    SciTech Connect

    Kinsman, G.F.; Land, E.H.

    1980-03-18

    A high voltage, low impedance laminar battery comprising a stack of series connected cells confined under pressure in a housing is described. The cells comprise laminar anodes, cathodes and separators. The cells are connected in series by laminar conductive intercell connectors. An annular spacer is associated with each cell. The spacers are separated by interdigitated ones of the separators and intercell connectors.

  8. High Voltage Seismic Generator

    NASA Astrophysics Data System (ADS)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  9. High voltage pulse conditioning

    DOEpatents

    Springfield, Ray M.; Wheat, Jr., Robert M.

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  10. HIGH VOLTAGE GENERATOR

    DOEpatents

    Schwemin, A.J.

    1959-03-17

    A generator is presented for producing relatively large currents at high voltages. In general, the invention comprises a plurality of capacitors connected in series by a plurality of switches alternately disposed with the capacitors. The circuit is mounted for movement with respect to contact members and switch closure means so that a load device and power supply are connected across successive numbers of capacitors, while the other capacitors are successively charged with the same power supply.

  11. High voltage generator

    DOEpatents

    Schwemin, A. J.

    1959-03-17

    A generator for producing relatively large currents at high voltages is described. In general, the invention comprises a plurality of capacitors connected in series by a plurality of switches alternately disposed with the capacitors. The above-noted circuit is mounted for movement with respect to contact members and switch closure means so that a load device and power supply are connected across successive numbers of capacitors, while the other capacitors are successively charged with the same power supply.

  12. HIGH VOLTAGE ION SOURCE

    DOEpatents

    Luce, J.S.

    1960-04-19

    A device is described for providing a source of molecular ions having a large output current and with an accelerated energy of the order of 600 kv. Ions are produced in an ion source which is provided with a water-cooled source grid of metal to effect maximum recombination of atomic ions to molecular ions. A very high accelerating voltage is applied to withdraw and accelerate the molecular ions from the source, and means are provided for dumping the excess electrons at the lowest possible potentials. An accelerating grid is placed adjacent to the source grid and a slotted, grounded accelerating electrode is placed adjacent to the accelerating grid. A potential of about 35 kv is maintained between the source grid and accelerating grid, and a potential of about 600 kv is maintained between the accelerating grid and accelerating electrode. In order to keep at a minimum the large number of oscillating electrons which are created when such high voltages are employed in the vicinity of a strong magnetic field, a plurality of high voltage cascaded shields are employed with a conventional electron dumping system being employed between each shield so as to dump the electrons at the lowest possible potential rather than at 600 kv.

  13. High voltage DC power supply

    DOEpatents

    Droege, T.F.

    1989-12-19

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively. 7 figs.

  14. High voltage DC power supply

    DOEpatents

    Droege, Thomas F.

    1989-01-01

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

  15. Low-voltage current noise in long quantum superconductor/insulator/normal-metal/insulator/superconductor junctions.

    SciTech Connect

    Kopnin, N. B.; Galperin, Y. M.; Vinokur, V.; Materials Science Division; Helsinki Univ. Tech.; L.D. Landau Inst. for Theoretical Physics; Univ. Oslo; A.F. Ioffe Physico-Tech. Inst. of Russian Academy of Sciences

    2007-01-01

    The current noise in long superconductor/insulator/normal-metal/insulator/superconductor junctions at low temperatures is sensitive to the population of the subgap states, which is far from equilibrium even at low bias voltages. A nonequilibrium distribution is established due to an interplay between voltage-driven interlevel Landau-Zener transitions and intralevel inelastic relaxation. The Fano factor (the ratio of the zero-frequency noise to the dc current) is enhanced drastically, being proportional to the number of times which a particle flies along the Andreev trajectory before it escapes from the level due to inelastic scattering. For weak Landau-Zener transitions, the enhancement is even larger due to a smaller dc current.

  16. APPARATUS FOR REGULATING HIGH VOLTAGE

    DOEpatents

    Morrison, K.G.

    1951-03-20

    This patent describes a high-voltage regulator of the r-f type wherein the modulation of the r-f voltage is accomplished at a high level, resulting in good stabilization over a large range of load conditions.

  17. Panelized high performance multilayer insulation

    NASA Technical Reports Server (NTRS)

    Burkley, R. A.; Shriver, C. B.; Stuckey, J. M.

    1968-01-01

    Multilayer insulation coverings with low conductivity foam spacers are interleaved with quarter mil aluminized polymer film radiation shields to cover flight type liquid hydrogen tankage of space vehicles with a removable, structurally compatible, lightweight, high performance cryogenic insulation capable of surviving extended space mission environments.

  18. Curing system for high voltage cross linked cables

    DOEpatents

    Bahder, George; Katz, Carlos; Bopp, Louis A.

    1978-01-01

    This invention makes extruded, vulcanized, high voltage cables insulated with thermosetting compounds at much higher rates of production and with superior insulation of reduced thickness and with reduced cavities or voids in the insulation. As the cable comes from an extruder, it passes into a curing chamber with a heat booster that quickly raises the insulation to a temperature at which it is cured much more quickly than with steam heating of the prior art. A high temperature liquid in contact with the insulation maintains the high temperature; and because of the greater curing heat, the cable can travel through the curing chamber at a faster rate and into a cooling tube where it contacts with a cooling liquid under high pressure. The insulation compound is treated to reduce the size of cavities; and the high pressure maintained by the curing and cooling mediums prevent expansion of cavities before the insulation is set.

  19. Current isolating epitaxial buffer layers for high voltage photodiode array

    DOEpatents

    Morse, Jeffrey D.; Cooper, Gregory A.

    2002-01-01

    An array of photodiodes in series on a common semi-insulating substrate has a non-conductive buffer layer between the photodiodes and the semi-insulating substrate. The buffer layer reduces current injection leakage between the photodiodes of the array and allows optical energy to be converted to high voltage electrical energy.

  20. Investigation of high voltage spacecraft system interactions with plasma environments

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Berkopec, F. D.; Purvis, C. K.; Grier, N.; Staskus, J.

    1978-01-01

    The exposure of high voltage spacecraft systems to the charged particle environment of space can produce interactions that will influence system operation. An experimental investigation of these interactions has been undertaken for insulator and conductor test surfaces biased up to plus or minus 1 kV in a simulated low earth orbit charged particle environment. It has been found that these interactions are controlled by the insulator surfaces surrounding the biased conductors. For positive applied voltages the electron current collection can be enhanced by the insulators. For negative applied voltages the insulator surface confines the voltage to the conductor region; this can cause arcing. Understanding these interactions and the technology to control their impact on system operation is essential to the design of solar cell arrays for ion drive propulsion applications that use direct drive power processing.

  1. Insulation system for high temperature superconductor cables

    NASA Astrophysics Data System (ADS)

    Michael, P. C.; Haight, A. E.; Bromberg, L.; Kano, K.

    2015-12-01

    Large-scale superconductor applications, like fusion magnets, require high-current capacity conductors to limit system inductance and peak operating voltage. Several cabling methods using high temperature superconductor (HTS) tapes are presently under development so that the unique high-field, high-current-density, high operating temperature characteristics of 2nd generation REBCO coated conductors can be utilized in next generation fusion devices. Large-scale magnets are generally epoxy impregnated to support and distribute electromagnetic stresses through the magnet volume. However, the present generation of REBCO coated conductors are prone to delamination when tensile stresses are applied to the broad surface of REBCO tapes; this can occur during epoxy cure, cooldown, or magnet energization. We present the development of an insulation system which effectively insulates HTS cabled conductors at high withstand voltage while simultaneously preventing the intrusion of the epoxy impregnant into the cable, eliminating degradation due to conductor delamination. We also describe a small-scale coil test program to demonstrate the cable insulation scheme and present preliminary test results.

  2. High Voltage TAL Performance

    NASA Technical Reports Server (NTRS)

    Jacobson, David T.; Jankovsky, Robert S.; Rawlin, Vincent K.; Manzella, David H.

    2001-01-01

    The performance of a two-stage, anode layer Hall thruster was evaluated. Experiments were conducted in single and two-stage configurations. In single-stage configuration, the thruster was operated with discharge voltages ranging from 300 to 1700 V. Discharge specific impulses ranged from 1630 to 4140 sec. Thruster investigations were conducted with input power ranging from 1 to 8.7 kW, corresponding to power throttling of nearly 9: 1. An extensive two-stage performance map was generated. Data taken with total voltage (sum of discharge and accelerating voltage) constant revealed a decrease in thruster efficiency as the discharge voltage was increased. Anode specific impulse values were comparable in the single and two-stage configurations showing no strong advantage for two-stage operation.

  3. A combined compensation method for the output voltage of an insulated core transformer power supply.

    PubMed

    Yang, L; Yang, J; Liu, K F; Qin, B; Chen, D Z

    2014-06-01

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA. PMID:24985809

  4. A combined compensation method for the output voltage of an insulated core transformer power supply

    NASA Astrophysics Data System (ADS)

    Yang, L.; Yang, J.; Liu, K. F.; Qin, B.; Chen, D. Z.

    2014-06-01

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.

  5. A combined compensation method for the output voltage of an insulated core transformer power supply

    SciTech Connect

    Yang, L.; Yang, J. Liu, K. F.; Qin, B.; Chen, D. Z.

    2014-06-15

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.

  6. Low voltage to high voltage level shifter and related methods

    NASA Technical Reports Server (NTRS)

    Mentze, Erik J. (Inventor); Hess, Herbert L. (Inventor); Buck, Kevin M. (Inventor); Cox, David F. (Inventor)

    2006-01-01

    A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

  7. Temperature controlled high voltage regulator

    DOEpatents

    Chiaro, Jr., Peter J.; Schulze, Gerald K.

    2004-04-20

    A temperature controlled high voltage regulator for automatically adjusting the high voltage applied to a radiation detector is described. The regulator is a solid state device that is independent of the attached radiation detector, enabling the regulator to be used by various models of radiation detectors, such as gas flow proportional radiation detectors.

  8. Stress-dependent voltage offsets from polymer insulators used in rock mechanics and material testing

    NASA Astrophysics Data System (ADS)

    Carlson, G. G.; Dahlgren, R.; Vanderbilt, V. C.; Johnston, M. J.; Dunson, C.; Gray, A.; Freund, F.

    2013-12-01

    Dielectric insulators are used in a variety of laboratory settings when performing experiments in rock mechanics, petrology, and electromagnetic studies of rocks in the fields of geophysics, material science, and civil engineering. These components may be used to electrically isolate geological samples from the experimental equipment, to perform a mechanical compliance function between brittle samples and the loading equipment, to match ultrasonic transducers, or perform other functions. In many experimental configurations the insulators bear the full brunt of force applied to the sample but do not need to withstand high voltages, therefore the insulators are often thin sheets of mechanically tough polymers. From an instrument perspective, transduction from various types of mechanical perturbation has been qualitatively compared for a number of polymers [1, 2] and these error sources are readily apparent during high-impedance measurements if not mitigated. However even when following best practices, a force-dependent voltage signal still remains and its behavior is explored in this presentation. In this experiment two thin sheets (0.25 mm) of high-density polyethylene (HDPE) were set up in a stack, held alternately between three aluminum bars; this stack was placed on the platen of a 60T capacity hydraulic testing machine. The surface area, A, over which the force is applied to the PE sheets in this sandwich is roughly 40 square cm, each sheet forming a parallel-plate capacitor having roughly 320 pF [3], assuming the relative dielectric permittivity of PE is ~2.3. The outer two aluminum bars were connected to the LO input of the electrometer and the central aluminum bar was connected to the HI input of a Keithley model 617 electrometer. Once the stack is mechanically well-seated with no air gaps, the voltage offset is observed to be a linear function of the baseline voltage for a given change in applied force. For a periodically applied force of 66.7 kN the voltage

  9. HIGH VOLTAGE ELECTRODES

    DOEpatents

    Murray, J.J.

    1963-04-23

    S>This patent relates to electrode structure for creating an intense direct current electric field which may have a field strength of the order of two to three times that heretofore obtained, with automatic suppression of arcing. The positive electrode is a conventional conductive material such as copper while the negative electrode is made from a special material having a resistivity greater than that of good conductors and less than that of good insulators. When an incipient arc occurs, the moderate resistivity of the negative electrode causes a momentary, localized decrease in the electric field intensity, thus suppressing the flow of electrons and avoiding arcing. Heated glass may be utilized for the negative electrode, since it provides the desired combination of resistivity, capacity, dielectric strength, mechani-cal strength, and thermal stability. (AEC)

  10. Conceptual definition of a high voltage power supply test facility

    NASA Technical Reports Server (NTRS)

    Biess, John J.; Chu, Teh-Ming; Stevens, N. John

    1989-01-01

    NASA Lewis Research Center is presently developing a 60 GHz traveling wave tube for satellite cross-link communications. The operating voltage for this new tube is - 20 kV. There is concern about the high voltage insulation system and NASA is planning a space station high voltage experiment that will demonstrate both the 60 GHz communications and high voltage electronics technology. The experiment interfaces, requirements, conceptual design, technology issues and safety issues are determined. A block diagram of the high voltage power supply test facility was generated. It includes the high voltage power supply, the 60 GHz traveling wave tube, the communications package, the antenna package, a high voltage diagnostics package and a command and data processor system. The interfaces with the space station and the attached payload accommodations equipment were determined. A brief description of the different subsystems and a discussion of the technology development needs are presented.

  11. Suppression of surface charge accumulation on Al2O3-filled epoxy resin insulator under dc voltage by direct fluorination

    NASA Astrophysics Data System (ADS)

    Zhang, Boya; Zhang, Guixin; Wang, Qiang; Li, Chuanyang; He, Jinliang; An, Zhenlian

    2015-12-01

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al2O3-filled epoxy resin were surface fluorinated using a F2/N2 mixture (12.5% F2) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  12. Evaluation Methods of Contamination Flashover Voltage Performance of Cylindrical Type Semi-conducting Glaze Porcelain Insulators

    NASA Astrophysics Data System (ADS)

    Yamada, Kazuma; Hayashi, Akio; Saka, Chiharu; Sakanishi, Kenji; Matsuoka, Ryosuke; Ito, Susumu; Fujii, Osamu

    Higher contamination flashover voltage of a semi-conducting glaze (SG) insulator owes primarily to the drying effect by leakage current flowing in the glaze. Significant reduction in contamination flashover voltage was confirmed on a cylindrical SG insulator when fog density was increased from 0.5g/m3 to 13g/m3 in clean fog test. The effect of de-energized duration between trip-out and re-energization on the contamination flashover voltage of a cylindrical SG insulator under cold-wet switch-on conditions was investigated. As the de-energized duration becomes shorter, the flashover voltage of a cylindrical SG insulator becomes higher. Higher contamination design voltages may be adopted even under cold-wet switch-on conditions.

  13. High Voltage Design Guidelines: A Timely Update

    NASA Technical Reports Server (NTRS)

    Hillard, G. Barry; Kirkici, H.; Ensworth, Clint (Technical Monitor)

    2001-01-01

    The evolving state of high voltage systems and their increasing use in the space program have called for a revision of the High Voltage Design Guidelines, Marshall Space Flight Center technical document MSFC-STD-531, originally issued September 1978 (previously 50 M05189b, October 1972). These guidelines deal in depth with issues relating to the specification of materials, particularly electrical insulation, as well as design practices and test methods. Emphasis is on corona and Paschen breakdown as well as plasma effects for Low Earth Orbiting systems. We will briefly review the history of these guidelines as well as their immediate predecessors and discuss their range of applicability. In addition, this document has served as the basis for several derived works that became focused, program-specific HV guidelines. We will briefly review two examples, guidelines prepared for the X-33 program and for the Space Shuttle Electric Auxiliary Power Unit (EAPU) upgrade.

  14. Stress-Dependent Voltage Offsets From Polymer Insulators Used in Rock Mechanics and Material Testing

    NASA Technical Reports Server (NTRS)

    Carlson, G. G.; Dahlgren, Robert; Gray, Amber; Vanderbilt, V. C.; Freund, F.; Johnston, M. J.; Dunson, C.

    2013-01-01

    Dielectric insulators are used in a variety of laboratory settings when performing experiments in rock mechanics, petrology, and electromagnetic studies of rocks in the fields of geophysics,material science, and civil engineering. These components may be used to electrically isolate geological samples from the experimental equipment, to perform a mechanical compliance function between brittle samples and the loading equipment, to match ultrasonic transducers, or perform other functions. In manyexperimental configurations the insulators bear the full brunt of force applied to the sample but do not need to withstand high voltages, therefore the insulators are often thin sheets of mechanically tough polymers. From an instrument perspective, transduction from various types of mechanical perturbation has beenqualitatively compared for a number of polymers [1, 2] and these error sources are readily apparent duringhigh-impedance measurements if not mitigated. However even when following best practices, a force dependent voltage signal still remains and its behavior is explored in this presentation. In this experimenttwo thin sheets (0.25 mm) of high-density polyethylene (HDPE) were set up in a stack, held alternatelybetween three aluminum bars; this stack was placed on the platen of a 60T capacity hydraulic testingmachine. The surface area, A, over which the force is applied to the PE sheets in this sandwich is roughly 40 square cm, each sheet forming a parallel-plate capacitor having roughly 320 pF [3], assuming therelative dielectric permittivity of PE is approximately 2.3. The outer two aluminum bars were connected to the LO input ofthe electrometer and the central aluminum bar was connected to the HI input of a Keithley model 617 electrometer. Once the stack is mechanically well-seated with no air gaps, the voltage offset is observed tobe a linear function of the baseline voltage for a given change in applied force. For a periodically appliedforce of 66.7 kN the

  15. High voltage lightning grounding device

    NASA Technical Reports Server (NTRS)

    Hoffman, R. G.; Peterson, V. S.

    1971-01-01

    Grounding device insertion in wire termination cabinets and terminal block modification prevent lightning-induced high voltage transients from reaching inputs or outputs of solid state instruments and control systems. Installation minimizes wiring confusion and achieves 100 percent protection.

  16. Bipolar high-repetition-rate high-voltage nanosecond pulser

    SciTech Connect

    Tian Fuqiang; Wang Yi; Shi Hongsheng; Lei Qingquan

    2008-06-15

    The pulser designed is mainly used for producing corona plasma in waste water treatment system. Also its application in study of dielectric electrical properties will be discussed. The pulser consists of a variable dc power source for high-voltage supply, two graded capacitors for energy storage, and the rotating spark gap switch. The key part is the multielectrode rotating spark gap switch (MER-SGS), which can ensure wider range modulation of pulse repetition rate, longer pulse width, shorter pulse rise time, remarkable electrical field distortion, and greatly favors recovery of the gap insulation strength, insulation design, the life of the switch, etc. The voltage of the output pulses switched by the MER-SGS is in the order of 3-50 kV with pulse rise time of less than 10 ns and pulse repetition rate of 1-3 kHz. An energy of 1.25-125 J per pulse and an average power of up to 10-50 kW are attainable. The highest pulse repetition rate is determined by the driver motor revolution and the electrode number of MER-SGS. Even higher voltage and energy can be switched by adjusting the gas pressure or employing N{sub 2} as the insulation gas or enlarging the size of MER-SGS to guarantee enough insulation level.

  17. High voltage transformers. (Latest citations from the Inspec database). NewSearch

    SciTech Connect

    Not Available

    1994-11-01

    The bibliography contains citations concerning materials and performance of insulators used for high voltage transformers. Topics examine use of mica-fibers, gases, mica filled epoxies, and ceramics. Effects of insulation aging are reviewed, and acceptance testing of high voltage power transformers and apparatus is also examined. (Contains a minimum of 104 citations and includes a subject term index and title list.)

  18. High temperature structural insulating material

    DOEpatents

    Chen, W.Y.

    1984-07-27

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800/sup 0/C), low thermal conductivity (below about 0.2 W/m/sup 0/C), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800/sup 0/C, a diameter within the range of 20-200 ..mu..m, and a wall thickness in the range of about 2 to 4 ..mu..m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  19. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-06

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  20. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-01

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  1. Stability of La2O3 Metal-Insulator-Metal Capacitors under Constant Voltage Stress

    NASA Astrophysics Data System (ADS)

    Shu-Hua Wu,; Chih-Kang Deng,; Tuo-Hung Hou,; Bi-Shiou Chiou,

    2010-04-01

    In this study, we demonstrate the stability of high-κ La2O3 metal-insulator-metal (MIM) capacitors under constant voltage stress (CVS). It was found that the variation in capacitance caused by CVS strongly depends on the injected charges regardless of stress biases. Furthermore, the quadratic voltage coefficient of capacitance (α) decreases with a logarithmic increase in dielectric loss. Charge trapping contributes to the relative capacitance variation under CVS while the reduced carrier mobility due to the stress-induced traps is responsible for the reduction of α. Additionally, high stability of 10-year lifetime is achieved for a 10-nm La2O3 MIM capacitor with an 11.4 fF/μm2 capacitance density.

  2. Stability of La2O3 Metal-Insulator-Metal Capacitors under Constant Voltage Stress

    NASA Astrophysics Data System (ADS)

    Wu, Shu-Hua; Deng, Chih-Kang; Hou, Tuo-Hung; Chiou, Bi-Shiou

    2010-04-01

    In this study, we demonstrate the stability of high-κ La2O3 metal-insulator-metal (MIM) capacitors under constant voltage stress (CVS). It was found that the variation in capacitance caused by CVS strongly depends on the injected charges regardless of stress biases. Furthermore, the quadratic voltage coefficient of capacitance (α) decreases with a logarithmic increase in dielectric loss. Charge trapping contributes to the relative capacitance variation under CVS while the reduced carrier mobility due to the stress-induced traps is responsible for the reduction of α. Additionally, high stability of 10-year lifetime is achieved for a 10-nm La2O3 MIM capacitor with an 11.4 fF/µm2 capacitance density.

  3. A novel method for predicting critical flashover (CFO) voltages insulation strength of multiple dielectrics on distribution overhead lines

    SciTech Connect

    Shwehdi, M.H.; Shahzad, F.

    1996-12-31

    Electric utilities are striving to improve the appearance of distribution lines, apply different combinations of insulating components to establish the necessary insulation for such lines, by the use of new insulators and simultaneously reduce lightning outages. The impulse critical flashover (CFO) voltages of many overhead line insulators are determined for single and multiple (porcelain, fiberglass, polymers and wood). Laboratory investigation and studies relating to the evaluation of CFO values of distribution lines for multiple dielectrics were reported. Data used by the industry for transmission lines are not fully applicable to estimate CFO`s for distribution lines. Many engineers concerned with the design or operation of high voltage transmission lines have devised methods to estimate the performance of lightning impulse. There is at the present time no such method available on estimating insulation strengths of multiple dielectrics of distribution lines subjected to impulse CFO. This paper presents a method of estimating the CFO insulation strengths of two and three dielectric combinations used on distribution overhead lines using the developed Extended Multi Curves (EMC). The proper use and evaluation of the insulation level by this novel method has a major influence on the design and cost of distribution line construction, application, also improving the performance of specific line designs.

  4. Improved Programmable High-Voltage Power Supply

    NASA Technical Reports Server (NTRS)

    Castell, Karen; Rutberg, Arthur

    1994-01-01

    Improved dc-to-dc converter functions as programmable high-voltage power supply with low-power-dissipation voltage regulator on high-voltage side. Design of power supply overcomes deficiencies of older designs. Voltage regulation with low power dissipation provided on high-voltage side.

  5. A Study on High Thermal Conductive Insulation for Claw Teeth Motors

    NASA Astrophysics Data System (ADS)

    Yoshitake, Yuichiro; Obata, Koji; Enomoto, Yuji; Okabe, Yoshiaki

    To increase the power density of motors in a wide range of fields from home appliance to power industry, we proposed two new high thermal conductive insulation systems for the motors. They were a glass cross insulation system and a resin coated insulation system without forced cooling devices such as a cooling fan. Their thermal and insulation characteristics were measured and analyzed, and optimum thermal conductive structures for claw teeth motors were discussed through robust design and thermal network analysis. Experiment on prototype motors with the highest thermal conductive epoxy resin (5 W/mK) and the proposed systems, revealed that the temperature rise of motor coils was decreased; their temperature reached 73 % of that of the motor coils with standard insulation and normal resin (0.6 W/mK). Furthermore, partial discharge inception voltage (PDIV) and breakdown voltage (BDV) were measured, and we verified that resin coated insulation motors could withstand as high a voltage as normal insulation motors.

  6. High Voltage Space Solar Arrays

    NASA Technical Reports Server (NTRS)

    Ferguson, D. C.; Hillard, G. B.; Vayner, B. V.; Galofaro, J. T.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Recent tests performed at the NASA Glenn Research Center and elsewhere have shown promise in the design and construction of high voltage (300-1000 V) solar arrays for space applications. Preliminary results and implications for solar array design will be discussed, with application to direct-drive electric propulsion and space solar power.

  7. LHCb calorimeters high voltage system

    NASA Astrophysics Data System (ADS)

    Gilitsky, Yu.; Golutvin, A.; Konoplyannikov, A.; Lefrancois, J.; Perret, P.; Schopper, A.; Soldatov, M.; Yakimchuk, V.

    2007-02-01

    The calorimeter system in LHCb aims to identify electrons, photons and hadrons. All calorimeters are equipped with Hamamatsu photo tubes as devices for light to signal conversion. Eight thousand R7899-20 tubes are used for electromagnetic and hadronic calorimeters and two hundred 64 channels multi-anode R7600-00-M64 for Scintillator-Pad/Preshower detectors. The calorimeter high voltage (HV) system is based on a Cockroft Walton (CW) voltage converter and a control board connected to the Experiment Control System (ECS) by serial bus. The base of each photomultiplier tube (PMT) is built with a high voltage converter and constructed on an individual printed circuit board, using compact surface mount components. The base is attached directly to the PMT. There are no HV cables in the system. A Field Programmable Gate Array (FPGA) is used on the control board as an interface between the ECS and the 200 control channels. The FPGA includes also additional functionalities allowing automated monitoring and ramp up of the high voltage values. This paper describes the HV system architecture, some technical details of the electronics implementation and summarizes the system performance. This safe and low power consumption HV electronic system for the photomultiplier tubes can be used for various biomedical apparatus too.

  8. Method and apparatus for connecting high voltage leads to a high temperature super-conducting transformer

    DOEpatents

    Golner, Thomas M.; Mehta, Shirish P.

    2005-07-26

    A method and apparatus for connecting high voltage leads to a super-conducting transformer is provided that includes a first super-conducting coil set, a second super-conducting coil set, and a third super-conducting coil set. The first, second and third super-conducting coil sets are connected via an insulated interconnect system that includes insulated conductors and insulated connectors that are utilized to connect the first, second, and third super-conducting coil sets to the high voltage leads.

  9. Planar LTCC transformers for high voltage flyback converters.

    SciTech Connect

    Schofield, Daryl; Schare, Joshua M.; Glass, Sarah Jill; Roesler, Alexander William; Ewsuk, Kevin Gregory; Slama, George; Abel, Dave

    2007-06-01

    This paper discusses the design and use of low-temperature (850 C to 950 C) co-fired ceramic (LTCC) planar magnetic flyback transformers for applications that require conversion of a low voltage to high voltage (> 100V) with significant volumetric constraints. Measured performance and modeling results for multiple designs showed that the LTCC flyback transformer design and construction imposes serious limitations on the achievable coupling and significantly impacts the transformer performance and output voltage. This paper discusses the impact of various design factors that can provide improved performance by increasing transformer coupling and output voltage. The experiments performed on prototype units demonstrated LTCC transformer designs capable of greater than 2 kV output. Finally, the work investigated the effect of the LTCC microstructure on transformer insulation. Although this paper focuses on generating voltages in the kV range, the experimental characterization and discussion presented in this work applies to designs requiring lower voltage.

  10. High-Voltage Droplet Dispenser

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.

    2003-01-01

    An apparatus that is extremely effective in dispensing a wide range of droplets has been developed. This droplet dispenser is unique in that it utilizes a droplet bias voltage, as well as an ionization pulse, to release a droplet. Apparatuses that deploy individual droplets have been used in many applications, including, notably, study of combustion of liquid fuels. Experiments on isolated droplets are useful in that they enable the study of droplet phenomena under well-controlled and simplified conditions. In this apparatus, a syringe dispenses a known value of liquid, which emerges from, and hangs onto, the outer end of a flat-tipped, stainless steel needle. Somewhat below the needle tip and droplet is a ring electrode. A bias high voltage, followed by a high-voltage pulse, is applied so as to attract the droplet sufficiently to pull it off the needle. The voltages are such that the droplet and needle are negatively charged and the ring electrode is positively charged.

  11. High-voltage CMOS detectors

    NASA Astrophysics Data System (ADS)

    Ehrler, F.; Blanco, R.; Leys, R.; Perić, I.

    2016-07-01

    High-voltage CMOS (HVCMOS) pixel sensors are depleted active pixel sensors implemented in standard commercial CMOS processes. The sensor element is the n-well/p-substrate diode. The sensor electronics are entirely placed inside the n-well which is at the same time used as the charge collection electrode. High voltage is used to deplete the part of the substrate around the n-well. HVCMOS sensors allow implementation of complex in-pixel electronics. This, together with fast signal collection, allows a good time resolution, which is required for particle tracking in high energy physics. HVCMOS sensors will be used in Mu3e experiment at PSI and are considered as an option for both ATLAS and CLIC (CERN). Radiation tolerance and time walk compensation have been tested and results are presented.

  12. Analysis Code for High Gradient Dielectric Insulator Surface Breakdown

    SciTech Connect

    Ives, Robert Lawrence; Verboncoeur, John; Aldan, Manuel

    2010-05-30

    High voltage (HV) insulators are critical components in high-energy, accelerator and pulsed power systems that drive diverse applications in the national security, nuclear weapons science, defense and industrial arenas. In these systems, the insulator may separate vacuum/non-vacuum regions or conductors with high electrical field gradients. These insulators will often fail at electric fields over an order of magnitude lower than their intrinsic dielectric strength due to flashover at the dielectric interface. Decades of studies have produced a wealth of information on fundamental processes and mechanisms important for flashover initiation, but only for relatively simple insulator configurations in controlled environments. Accelerator and pulsed power system designers are faced with applying the fundamental knowledge to complex, operational devices with escalating HV requirements. Designers are forced to rely on “best practices” and expensive prototype testing, providing boundaries for successful operation. However, the safety margin is difficult to estimate, and system design must be very conservative for situations where testing is not practicable, or replacement of failed parts is disruptive or expensive. The Phase I program demonstrated the feasibility of developing an advanced code for modeling insulator breakdown. Such a code would be of great interest for a number of applications, including high energy physics, microwave source development, fusion sciences, and other research and industrial applications using high voltage devices.

  13. Sialons as high temperature insulators

    NASA Technical Reports Server (NTRS)

    Phillips, W. M.; Kuo, Y. S.

    1978-01-01

    Sialons were evaluated for application as high temperature electrical insulators in contact with molybdenum and tungsten components in hard vacuum applications. Both D.C. and variable frequency A.C. resistivity data indicate the sialons to have electrical resistivity similar to common oxide in the 1000 C or higher range. Metallographic evaluations indicate good bonding of the type 15R ALN polytype to molybdenum and tungsten. The beta prime or modified silicon nitride phase was unacceptable in terms of vacuum stability. Additives effect on electrical resistivity. Similar resistivity decreases were produced by additions of molybdenum or tungsten to form cermets. The use of hot pressing at 1800 C with ALN, Al2 O3 and Si3N4 starting powders produced a better product than did a combination of SiO2 and AIN staring powders. It was indicated that sialons will be suitable insulators in the 1600K range in contact with molybdenum or tungsten if they are produced as a pure ceramic and subsequently bonded to the metal components at temperatures in the 1600K range.

  14. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    DOEpatents

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  15. Measured and theoretical characterization of the RF properties of stacked, high-gradient insulator material

    SciTech Connect

    Houck, T. L., LLNL

    1997-05-09

    Recent high-voltage breakdown experiments of periodic metallic-dielectric insulating structures have suggested several interesting high-gradient applications. One such area is the employment of high-gradient insulators in high-current, electron-beam, accelerating induction modules. For this application, the understanding of the rf characteristics of the insulator plays an important role in estimating beam-cavity interactions. In this paper, we examine the rf properties of the insulator comparing simulation results with experiment. Different insulator designs are examined to determine their rf transmission properties in gap geometries.

  16. Voltage-induced Metal-Insulator Transitions in Perovskite Oxide Thin Films Doped with Strongly Correlelated Electrons

    NASA Astrophysics Data System (ADS)

    Wang, Yudi; Gil Kim, Soo; Chen, I.-Wei

    2007-03-01

    We have observed a reversible metal-insulator transition in perovskite oxide thin films that can be controlled by charge trapping pumped by a bipolar voltage bias. In the as-fabricated state, the thin film is metallic with a very low resistance comparable to that of the metallic bottom electrode, showing decreasing resistance with decreasing temperature. This metallic state switches to a high-resistance state after applying a voltage bias: such state is non-ohmic showing a negative temperature dependence of resistance. Switching at essentially the same voltage bias was observed down to 2K. The metal-insulator transition is attributed to charge trapping that disorders the energy of correlated electron states in the conduction band. By increasing the amount of charge trapped, which increases the disorder relative to the band width, increasingly more insulating states with a stronger temperature dependence of resistivity are accessed. This metal-insulator transition provides a platform to engineer new nonvolatile memory that does not require heat (as in phase transition) or dielectric breakdown (as in most other oxide resistance devices).

  17. High Gradient Multilayer Insulator Technology

    SciTech Connect

    Sampayan, S E; Caporaso, G J; Nunnally, W C; Sanders, D M; Watson, J A; Krogh, M L; Anderson, H U

    2004-06-03

    We are investigating a novel insulator concept that involves the use of alternating layers of conductors and insulators with periods less than 1 mm. These structures perform 1.5 to 4 times better than conventional insulators in long pulse, short pulse, and alternating polarity applications. We survey our ongoing studies investigating the performance under long pulse electron beam, short pulse, and full reversing conditions.

  18. Current–voltage characteristics of organic heterostructure devices with insulating spacer layers

    DOE PAGESBeta

    Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

    2015-09-01

    The dark current density in donor/acceptor organic planar heterostructure devices at a given forward voltage bias can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of interfacial exciplex states. If the exciplex recombination rate limits current flow, an insulating interface layer decreases the dark current. However, if the exciplex formation rate limits the current, an insulating interface layer may increase the dark current. As a result, we present a device model to describe this behavior, and wemore » discuss relevant experimental data.« less

  19. Current–voltage characteristics of organic heterostructure devices with insulating spacer layers

    SciTech Connect

    Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

    2015-09-01

    The dark current density in donor/acceptor organic planar heterostructure devices at a given forward voltage bias can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of interfacial exciplex states. If the exciplex recombination rate limits current flow, an insulating interface layer decreases the dark current. However, if the exciplex formation rate limits the current, an insulating interface layer may increase the dark current. As a result, we present a device model to describe this behavior, and we discuss relevant experimental data.

  20. Fabrication of high gradient insulators by stack compression

    SciTech Connect

    Harris, John Richardson; Sanders, Dave; Hawkins, Steven Anthony; Norona, Marcelo

    2014-04-29

    Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.

  1. Insulator damage in high current discharges

    NASA Astrophysics Data System (ADS)

    Ranon, P. M.; Kristiansen, M.; Lehr, F. M.; Hatfield, L. L.

    1986-11-01

    The degradation of the hold-off voltage capability of several composite candidates for railgun insulators was studied experimentally. The materials examined were BN, alumina (Coor's ceramic), and two types of laminated fiberglass/epoxy (FGE I and FGE II). Sample 1 cm thick plates of the insulators were inserted into a surface discharge switch (SDS) with a gap of 1.6 in., i.e., an initial hold-off voltage of 40 kV. FGE I retained the hold-off voltage for more than 10,000 shots at a current of 1 kA maximum, but degraded significantly after 50 shots at currents over 200 kA. BN shattered when the repetition rate exceeded 1 pulse/sec.

  2. High pressure electrical insulated feed thru connector

    DOEpatents

    Oeschger, Joseph E.; Berkeland, James E.

    1979-11-13

    A feed-thru type hermetic electrical connector including at least one connector pin feeding through an insulator block within the metallic body of the connector shell. A compression stop arrangement coaxially disposed about the insulator body is brazed to the shell, and the shoulder on the insulator block bears against this top in a compression mode, the high pressure or internal connector being at the opposite end of the shell. Seals between the pin and an internal bore at the high pressure end of the insulator block and between the insulator block and the metallic shell at the high pressure end are hermetically brazed in place, the first of these also functioning to transfer the axial compressive load without permitting appreciable shear action between the pin and insulator block.

  3. High Voltage TAL Erosion Characterization

    NASA Technical Reports Server (NTRS)

    Jacobson, David T.

    2003-01-01

    Extended operation of a D-80 anode layer thruster at high voltage was investigated. The thruster was operated for 1200 hours at 700 Volts and 4 Amperes. Laser profilometry was employed to quantify the erosion of the thruster's graphite guard rings and electrodes at 0, 300, 600, 900, and 1200 hours. Thruster performance and electrical characteristics were monitored over the duration of the investigation. The guard rings exhibited asymmetric erosion that was greatest in the region of the cathode. Erosion of the guard rings exposed the magnet poles between 600 to 900 hours of operation.

  4. Investigation on onset voltage and conduction channel temperature in voltage-induced metal-insulator transition of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Yoon, Joonseok; Kim, Howon; Mun, Bongjin Simon; Park, Changwoo; Ju, Honglyoul

    2016-03-01

    The characteristics of onset voltages and conduction channel temperatures in the metal-insulator transition (MIT) of vanadium dioxide (VO2) devices are investigated as a function of dimensions and ambient temperature. The MIT onset voltage varies from 18 V to 199 V as the device length increases from 5 to 80 μm at a fixed width of 100 μm. The estimated temperature at local conduction channel increases from 110 to 370 °C, which is higher than the MIT temperature (67 °C) of VO2. A simple Joule-heating model is employed to explain voltage-induced MIT as well as to estimate temperatures of conduction channel appearing after MIT in various-sized devices. Our findings on VO2 can be applied to micro- to nano-size tunable heating devices, e.g., microscale scanning thermal cantilevers and gas sensors.

  5. Field Test of Fiber-Optic Voltage and Current Sensors Applied to Gas Insulated Substation

    NASA Astrophysics Data System (ADS)

    Kuroda, Y.; Abe, Y.; Kuwahara, H.; Yoshinaga, K.

    1986-08-01

    The fiber-optic voltage and current sensors applied for 84kV three phase type gas insulated substation (GIS) were tested in order to see the advantages of these sensors practically in adverse field condition. The application technologies and field endurance test results of the sensors are described in this paper.

  6. High-voltage R-F feedthrough bushing

    DOEpatents

    Grotz, G.F.

    1982-09-03

    Described is a multi-element, high voltage radio frequency bushing for transmitting rf energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  7. Partial discharge in a high voltage experimental test assembly

    SciTech Connect

    Koss, R.J.; Brainard, J.P.

    1998-07-01

    This study was initiated when a new type of breakdown occurred in a high voltage experimental test assembly. An anomalous current pulse was observed, which indicated partial discharges, some leading to total breakdowns. High voltage insulator defects are shown along with their effect on the electrostatic fields in the breakdown region. OPERA electromagnetic field modeling software is used to calculate the fields and present a cause for the discharge. Several design modifications are investigated and one of the simplest resulted in a 25% decrease in the field at the discharge surface.

  8. High voltage transformers. (Latest citations from the INSPEC database). Published Search

    SciTech Connect

    1997-05-01

    The bibliography contains citations concerning materials and performance of insulators used for high voltage transformers. Topics examine use of mica-fibers, gases, mica filled epoxies, and ceramics. Effects of insulation aging are reviewed, and acceptance testing of high voltage power transformers and apparatus is also examined.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  9. High voltage feed through bushing

    DOEpatents

    Brucker, J.P.

    1993-04-06

    A feed through bushing for a high voltage diode provides for using compression sealing for all sealing surfaces. A diode assembly includes a central conductor extending through the bushing and a grading ring assembly circumferentially surrounding and coaxial with the central conductor. A flexible conductive plate extends between and compressively seals against the central conductor and the grading ring assembly, wherein the flexibility of the plate allows inner and outer portions of the plate to axially translate for compression sealing against the central conductor and the grading ring assembly, respectively. The inner portion of the plate is bolted to the central conductor for affecting sealing. A compression beam is also bolted to the central conductor and engages the outer portion of the plate to urge the outer portion toward the grading ring assembly to obtain compression sealing therebetween.

  10. Voltage breakdown between closely spaced electrodes over polymeric insulator surfaces in air

    NASA Astrophysics Data System (ADS)

    Gray, Eoin W.; Harrington, Daniel J.

    1982-01-01

    Voltage breakdowns of some narrow gap electrodes [2-10 mil (0.05-0.25 mm)] on polymeric insulator surfaces (epoxy-glass and triazine) have been examined over the pressure range from atmospheric pressure to 127 Torr and are shown to be an air breakdown modified by the presence of the insulator. Breakdown values as a function of the number of the breakdown and discharge energy level were also examined. In the worst case the breakdown voltage was observed to decrease by approximately 1300 V after about five successive breakdowns. The breakdown voltage between narrowly spaced metallic contacts on dielectric surfaces has been assumed to exhibit a Gaussian distribution. Non-Gaussian, bimodal distributions have been observed in the present work. These bimodal distributions, found on fine line epoxy-glass and triazine printed wiring boards, and attempts for explanation in terms of the flashover discharge initiating mechanisms, including the effects of ultraviolet radiation and a negative-ion flux on breakdown, are described. Negative ions appear to reduce the standard deviation but do not reduce the breakdown voltage. Ultraviolet radiation reduces both the standard deviation and the breakdown voltage. Increasing the conductor overlap distance (line length) reduced the breakdown voltage.

  11. 30 CFR 75.833 - Handling high-voltage trailing cables.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. ASTM F496-02a may be obtained... must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which include the rubber gloves and leather outer protector gloves, or are using insulated cable handling...

  12. 30 CFR 75.833 - Handling high-voltage trailing cables.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. ASTM F496-02a may be obtained... must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which include the rubber gloves and leather outer protector gloves, or are using insulated cable handling...

  13. 30 CFR 75.833 - Handling high-voltage trailing cables.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. ASTM F496-02a may be obtained... must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which include the rubber gloves and leather outer protector gloves, or are using insulated cable handling...

  14. 30 CFR 75.833 - Handling high-voltage trailing cables.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. ASTM F496-02a may be obtained... must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which include the rubber gloves and leather outer protector gloves, or are using insulated cable handling...

  15. 30 CFR 75.833 - Handling high-voltage trailing cables.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... incorporation by reference in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. ASTM F496-02a may be obtained... must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which include the rubber gloves and leather outer protector gloves, or are using insulated cable handling...

  16. On the Degradation Mechanism of Low-Voltage Underground Cable with Poly(Vinyl Chloride) Insulation

    NASA Astrophysics Data System (ADS)

    Tawancy, H. M.; Hassan, M.

    2016-06-01

    A study has been undertaken to determine the degradation mechanism leading to localized short-circuit failures of an underground low-voltage cable with PVC insulation. It is shown that that the insulation of outer sheath and conductor cores has been cracked by thermal degradation involving dehydrochlorination, oxidation, and loss of plasticizers leading to current leakage between the cores. Most evidence points out that overheating due to poor connection of copper wires as well as a chemically active soil has caused the observed degradation.

  17. Low power, scalable multichannel high voltage controller

    DOEpatents

    Stamps, James Frederick; Crocker, Robert Ward; Yee, Daniel Dadwa; Dils, David Wright

    2006-03-14

    A low voltage control circuit is provided for individually controlling high voltage power provided over bus lines to a multitude of interconnected loads. An example of a load is a drive for capillary channels in a microfluidic system. Control is distributed from a central high voltage circuit, rather than using a number of large expensive central high voltage circuits to enable reducing circuit size and cost. Voltage is distributed to each individual load and controlled using a number of high voltage controller channel switches connected to high voltage bus lines. The channel switches each include complementary pull up and pull down photo isolator relays with photo isolator switching controlled from the central high voltage circuit to provide a desired bus line voltage. Switching of the photo isolator relays is further controlled in each channel switch using feedback from a resistor divider circuit to maintain the bus voltage swing within desired limits. Current sensing is provided using a switched resistive load in each channel switch, with switching of the resistive loads controlled from the central high voltage circuit.

  18. Low power, scalable multichannel high voltage controller

    DOEpatents

    Stamps, James Frederick; Crocker, Robert Ward; Yee, Daniel Dadwa; Dils, David Wright

    2008-03-25

    A low voltage control circuit is provided for individually controlling high voltage power provided over bus lines to a multitude of interconnected loads. An example of a load is a drive for capillary channels in a microfluidic system. Control is distributed from a central high voltage circuit, rather than using a number of large expensive central high voltage circuits to enable reducing circuit size and cost. Voltage is distributed to each individual load and controlled using a number of high voltage controller channel switches connected to high voltage bus lines. The channel switches each include complementary pull up and pull down photo isolator relays with photo isolator switching controlled from the central high voltage circuit to provide a desired bus line voltage. Switching of the photo isolator relays is further controlled in each channel switch using feedback from a resistor divider circuit to maintain the bus voltage swing within desired limits. Current sensing is provided using a switched resistive load in each channel switch, with switching of the resistive loads controlled from the central high voltage circuit.

  19. Suppression of surface charge accumulation on Al{sub 2}O{sub 3}-filled epoxy resin insulator under dc voltage by direct fluorination

    SciTech Connect

    Zhang, Boya; Zhang, Guixin Li, Chuanyang; He, Jinliang; Wang, Qiang; An, Zhenlian

    2015-12-15

    Surface charge accumulation on insulators under high dc voltage is a major factor that may lead to the reduction of insulation levels in gas insulated devices. In this paper, disc insulators made of Al{sub 2}O{sub 3}-filled epoxy resin were surface fluorinated using a F{sub 2}/N{sub 2} mixture (12.5% F{sub 2}) at 50 °C and 0.1 MPa for different durations of 15 min, 30 min and 60 min. A dc voltage was applied to the insulator for 30 min and the charge density on its surface was measured by an electrostatic probe. The results revealed significant lower surface charge densities on the fluorinated insulators in comparison with the original one. Surface conductivity measurements indicated a higher surface conductivity by over three orders of magnitude after fluorination, which would allow the charges to transfer along the surface and thus may suppress their accumulation. Further, attenuated total reflection infrared analysis and surface morphology observations of the samples revealed that the introduction of fluoride groups altered the surface physicochemical properties. These structure changes, especially the physical defects reduced the depth of charge traps in the surface layer, which was verified by the measurement of energy distributions of the electron and hole traps based on the isothermal current theory. The results in this paper demonstrate that fluorination can be a promising and effective method to suppress surface charge accumulation on epoxy insulators in gas insulated devices.

  20. Evaluation of Humidity Characteristic of Insulation Resistance Occurred between Output Terminals and Chassis on Some Zener Voltage Standards

    NASA Astrophysics Data System (ADS)

    Nishinaka, Hidefumi

    Four Zener voltage standards ( Fluke 732B ) belonging to National Metrology Institute of Japan (NMIJ), AIST have contained in a particularly designed box that is called an “up-graded box". This box need for enhancing the insulation resistance occurred between the 1.018 V output terminal and chassis of the Zener voltage standard, because the 1.018 V output voltages have 1kΩ output-resistance. Hence, affect refer to best measurement capability 4 nV (k=1) of the 1.018 V output voltage arises from load effect between the insulation resistance and 1kΩ output-resistance. Moreover, this insulation resistance has an effect on the environmental humidity-change of 40%RH, 50%RH, 60%RH, 65%RH and 70%RH. Therefore, this paper revealed type B standard uncertainty of the 1.018 V output voltages arose by the humidity characteristic of the insulation resistance.

  1. Electrical aging of stator insulation of low voltage rotating machines supplied by inverters

    SciTech Connect

    Bellomo, J.P.; Lebey, T.; Oraison, J.M.; Peltier, F.

    1996-12-31

    Nowadays, use of inverters for speed variation of low voltage motors becomes more and more usual. The most common technology for this kind of apparatus uses the Pulse Width Modulation (PWM). It is characterized by a square voltage shape with short rise and fall times. In order to insure the quality of turn to ground insulation submitted to these constraints, a study on the aging of Polyethylene terephthalate (Mylar{trademark}) has been undertaken. Influence of rise and fall times, frequency and voltage magnitude has been investigated for time duration up to 1,000 hours. To realize a good voltage application, samples were previously metalized. Two different behaviors according to the rise time and magnitude are observed. For long rise and fall times, changes in the capacity values are obtained although, for smaller rise or fall times, a degradation of the metalized electrode appears. A surface charge generation process is discussed to explain this phenomena.

  2. Metal-insulator-semi-conductor studies of lead telluride. [capacitance and conductance-voltage characteristics

    NASA Technical Reports Server (NTRS)

    Lilly, D. A.; Joslin, D. E.; Kan, H. K. A.

    1976-01-01

    The capacitance and conductance-voltage characteristics were measured on metal-insulator-semiconductor capacitors fabricated with zirconium dioxide films on single-crystal lead telluride. At 77 K, on both n- and p-type substrates, evidence of surface potential control was obtained. Comparison of the measured capacitance-voltage characteristics with those calculated from the equilibrium solution of the one-dimensional Poisson equation indicated qualitative agreement, although the slope of the measured capacitance in the region near the capacitance minimum was less steep than calculated.

  3. Development of optimized PPP insulated pipe-cable systems in the commercial voltage range. Final report

    SciTech Connect

    Allam, E.M.; McKean, A.L.

    1992-05-01

    The primary objectives of this project included the development of an alternate domestic source of Paper-Polypropylene-Paper (PPP) laminate and the development of optimized designs for PPP-insulated pipe-type cable systems in the commercial voltage range. The development of a domestic source of PPP laminate was successfully completed. This laminate was utilized throughout the program for fabrication of full-size prototype cables submitted for laboratory qualification tests. Selected cables at rated voltages of 138, 230 and 345kV have been designed, fabricated and subjected to the series of qualification tests leading to full laboratory qualification. An optimized design of 2000 kcmil, 345kV cable insulated with 600 mils of domestic PPP laminate was fabricated and successfully passed all laboratory qualification tests. This cable design was subsequently installed at Waltz Mill to undergo the series of field tests leading to full commercial qualification.

  4. Development of optimized PPP insulated pipe-cable systems in the commercial voltage range

    SciTech Connect

    Allam, E.M.; McKean, A.L. )

    1992-05-01

    The primary objectives of this project included the development of an alternate domestic source of Paper-Polypropylene-Paper (PPP) laminate and the development of optimized designs for PPP-insulated pipe-type cable systems in the commercial voltage range. The development of a domestic source of PPP laminate was successfully completed. This laminate was utilized throughout the program for fabrication of full-size prototype cables submitted for laboratory qualification tests. Selected cables at rated voltages of 138, 230 and 345kV have been designed, fabricated and subjected to the series of qualification tests leading to full laboratory qualification. An optimized design of 2000 kcmil, 345kV cable insulated with 600 mils of domestic PPP laminate was fabricated and successfully passed all laboratory qualification tests. This cable design was subsequently installed at Waltz Mill to undergo the series of field tests leading to full commercial qualification.

  5. High-Tech, Low-Temp Insulation

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Under an SBIR (Small Business Innovative Research) contract with Ames, S.D. Miller & Associates developed new manufacturing methods for multi-layer metal spacecraft insulation that could significantly reduce launch weight and launch costs. The new honeycomb structure is more efficient than fibers for insulation. Honeycombs can be made from metals for high temperature uses, even plastic insulation from recycled milk bottles. Under development are blankets made from recycled milk bottles which will be field tested by the Red Cross and ambulance companies. Currently available are honeycomb mittens based on the same technology.

  6. Electromagnetic compatibility in high-voltage engineering

    NASA Astrophysics Data System (ADS)

    Vanhouten, Marinus Albertus

    1990-09-01

    Electro Magnetic Compatibility (EMC) concepts for an efficient and consistant approach to practical interference problems are described. A critical analysis of 'grounding' is given. The design of a 'differentiated/integrated' system to measure fast voltage transients is described. Measurements of steep transient voltages across interruptions in a Gas Insulated Switchear (GIS) installation, due to switching actions, are presented. Available means to reduce the influence of this interference source on the measuring are discussed. General conclusions are that general, linear and basic design methods for the protection of electronics and (large) interconnected electrical systems against interference can be developed which can save production costs and research time. The design methods described concentrate on the reduction of dangerous voltages between critical points which can be achieved by correct layout choice.

  7. Electro-Optical High-Voltage Sensors

    NASA Technical Reports Server (NTRS)

    Gottsche, Allan; Johnston, Alan R.

    1992-01-01

    Electro-optical sensors for measuring high voltages developed for use in automatically controlled power-distribution systems. Sensors connected to optoelectronic interrogating equipment by optical fibers. Because sensitive material and optical fibers are all dielectric, no problem in electrically isolating interrogating circuitry from high voltage, and no need for voltage dividers. Sensor signals transmitted along fibers immune to electromagnetic noise at radio and lower frequencies.

  8. Bombarding insulating foils with highly energetic ions

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; de Filippo, E.; Hagmann, S.; Rothard, H.; Volant, C.

    Insulating (MYLAR), semi-insulating (MYLAR-Au) and conducting foils have been bombarded by very energetic 64 MeV u-1 78Kr32+ ions. The velocity spectra of fast electrons emitted in the backward and forward directions have been measured and analyzed as a function of the elapsed time in the run. A shift of binary encounter and convoy electrons emitted in the forward direction toward lower velocities has been observed with insulating targets. No such shift occurs with metallic targets. The surface potential evolves with time (i.e. ion fluence) both at forward and backward emission angle. It is shown that strong bulk charging of insulating targets leads to a positive potential as high as 9 kV before charge breakdown.

  9. Switch contact device for interrupting high current, high voltage, AC and DC circuits

    DOEpatents

    Via, Lester C.; Witherspoon, F. Douglas; Ryan, John M.

    2005-01-04

    A high voltage switch contact structure capable of interrupting high voltage, high current AC and DC circuits. The contact structure confines the arc created when contacts open to the thin area between two insulating surfaces in intimate contact. This forces the arc into the shape of a thin sheet which loses heat energy far more rapidly than an arc column having a circular cross-section. These high heat losses require a dramatic increase in the voltage required to maintain the arc, thus extinguishing it when the required voltage exceeds the available voltage. The arc extinguishing process with this invention is not dependent on the occurrence of a current zero crossing and, consequently, is capable of rapidly interrupting both AC and DC circuits. The contact structure achieves its high performance without the use of sulfur hexafluoride.

  10. An amorphous titanium dioxide metal insulator metal selector device for resistive random access memory crossbar arrays with tunable voltage margin

    NASA Astrophysics Data System (ADS)

    Cortese, Simone; Khiat, Ali; Carta, Daniela; Light, Mark E.; Prodromakis, Themistoklis

    2016-01-01

    Resistive random access memory (ReRAM) crossbar arrays have become one of the most promising candidates for next-generation non volatile memories. To become a mature technology, the sneak path current issue must be solved without compromising all the advantages that crossbars offer in terms of electrical performances and fabrication complexity. Here, we present a highly integrable access device based on nickel and sub-stoichiometric amorphous titanium dioxide (TiO2-x), in a metal insulator metal crossbar structure. The high voltage margin of 3 V, amongst the highest reported for monolayer selector devices, and the good current density of 104 A/cm2 make it suitable to sustain ReRAM read and write operations, effectively tackling sneak currents in crossbars without compromising fabrication complexity in a 1 Selector 1 Resistor (1S1R) architecture. Furthermore, the voltage margin is found to be tunable by an annealing step without affecting the device's characteristics.

  11. High voltage MOSFET switching circuit

    DOEpatents

    McEwan, Thomas E.

    1994-01-01

    The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET.

  12. High voltage MOSFET switching circuit

    DOEpatents

    McEwan, T.E.

    1994-07-26

    The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET. 2 figs.

  13. Voltage-Controlled Magnetic Anisotropy in Heavy Metal/Ferromagnet/Insulator-Based Structures

    NASA Astrophysics Data System (ADS)

    Li, Xiang

    Electric-field assisted writing of magnetic memory that exploits the voltage-controlled magnetic anisotropy (VCMA) effect offers a great potential for high density and low power applications. Magnetoelectric Random Access Memory (MeRAM) has been investigated due to its lower switching current, compared with traditional current-controlled devices utilizing spin transfer torque (STT) or spin-orbit torque (SOT) for magnetization switching. It is of great promise to integrate MeRAM into the advanced CMOS back-end-of-line (BEOL) processes for on-chip embedded applications, and enable non-volatile electronic systems with low static power dissipation and instant-on operation capability. In this thesis, different heavy metal|ferromagnet|insulator-based structures are grown by magnetron sputtering to improve the VCMA effect over the traditional Ta|CoFeB|MgO-based structures. We also established an accurate measurement technique for VCMA characterization. An improved thermal annealing stability of VCMA over 400°C is achieved in Mo|CoFeB|MgO-based structures. In addition, we observed a weak CoFeB thickness dependence of both VCMA coefficient and interfacial perpendicular magnetic anisotropy (PMA) in both Ta|CoFeB|MgO and Mo|CoFeB|MgO-based structures.

  14. Substation voltage upgrading. Volume 2, Substation insulation tests and design for fast front lightning impulses: Final report

    SciTech Connect

    Panek, J.; Elahi, H.; Lux, A.; Imece, A.F.; LaPanse, R.A.; Stewart, J.R.

    1992-04-01

    This report addresses specific issues to support sound yet not unduly conservative uprating practices for substations. The main parts of the report cover the insulation withstand and overvoltage protection aspects, environmental measurements, reliability criteria, and industry experience. First the insulation design concerns are addressed. Substation stress by a backflashover of the line insulation due to lightning in the vicinity of the substation is recognized as a critical stress. A representative part of a 550 kV BIL substation was erected at the EPRI High Voltage Transmission Research Center, where also a special test circuit was assembled to produce a fast front, slow tail (0.2/200 {mu}s) wave. The substation as well as some special configurations were tested for line-to-ground and line-to-line withstand. Computer studies were performed to complement the test results. A number of important conclusions was reached. The most prominent result in that the high frequency oscillations, as caused by reflections within the substation, do not effect the Critical Flashover Voltage (CFO). The present practice, based on the highest peak is therefore very conservative. The slow tail of the wave appears to dictate the CFO. An arrester model for computer studies to represent very fast as well as slow phenomena was derived. It is based on full scale arrester test data, made available in this project. The computer program to calculate arrester model parameters is also a part of the report. The electric environmental measurements are reported for the tested substation at the HVTRC and for the uprated substation of Public Service Company of Colorado, both before and after the uprating. The performance is satisfactory when corona free hardware is used. Insulation design criteria are analyzed based on substation reliability, the system viewpoint and consequences of the failure. Utility experience with uprated substations is reviewed.

  15. Insulation Blankets for High-Temperature Use

    NASA Technical Reports Server (NTRS)

    Goldstein, H.; Leiser, D.; Sawko, P. M.; Larson, H. K.; Estrella, C.; Smith, M.; Pitoniak, F. J.

    1986-01-01

    Insulating blanket resists temperatures up to 1,500 degrees F (815 degrees C). Useful where high-temperature resistance, flexibility, and ease of installation are important - for example, insulation for odd-shaped furnaces and high-temperature ducts, curtains for furnace openings and fire control, and conveyor belts in hot processes. Blanket is quilted composite consisting of two face sheets: outer one of silica, inner one of silica or other glass cloth with center filling of pure silica glass felt sewn together with silica glass threads.

  16. Interaction of high voltage surfaces with the space plasma

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Robinson, R. S.

    1980-01-01

    High voltage solar arrays provide spacecraft power while optimizing mass and power efficiency. Operating such arrays in the space plasma environment can result in anomalously large currents being collected through insulation defects. Two thicknesses of the insulating material were tested, with no effect found due to insulator thickness. In these tests the polyimide thickness was always much less than the pinhole diameter. The pinhole area was varied over an area range of more than 30:1. It was found that the current collected was independent of the pinhole area for hole diameters from 0.35 to 2.0 mm. Two types of adhesives were tried in two different configurations. The adhesives were chosen for their extreme difference in vacuum qualifications. Neither adhesive types nor configuration made a significant difference in current collection. The temperature of the insulating material was also varied. It was found that current collection decreased with increasing temperature. Tests were conducted to see if pinhole current collection decreased with time, as was indicated by the effects of several short tests. Current was collected for over four hours while the conductor potential was held constant at 1000 volts. A smooth decrease with time was not observed, but rather a roughly constant current collection with brief surges to high values. Tests were also conducted with the simulated solar cell biased negative. The current was found to be proportional to pinhole area.

  17. Radiatively heated high voltage pyroelectric crystal pulser

    NASA Astrophysics Data System (ADS)

    Antolak, A. J.; Chen, A. X.; Leung, K.-N.; Morse, D. H.; Raber, T. N.

    2014-01-01

    Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

  18. Ultrasonic evaluation of high voltage circuit boards

    NASA Technical Reports Server (NTRS)

    Klima, S. J.; Riley, T. J.

    1976-01-01

    Preliminary observations indicate that an ultrasonic scanning technique may be useful as a quick, low cost, nondestructive method for judging the quality of circuit board materials for high voltage applications. Corona inception voltage tests were conducted on fiberglass-epoxy and fiberglass-polyimide high pressure laminates from 20 to 140 C. The same materials were scanned ultrasonically by utilizing the single transducer, through-transmission technique with reflector plate, and recording variations in ultrasonic energy transmitted through the board thickness. A direct relationship was observed between ultrasonic transmission level and corona inception voltage. The ultrasonic technique was subsequently used to aid selection of high quality circuit boards for the Communications Technology Satellite.

  19. High voltage space plasma interactions

    NASA Astrophysics Data System (ADS)

    McCoy, J. E.

    1980-07-01

    Two primary problems resulted from plasma interactions; one of concern to operations in geosynchronous orbit (GEO), the other in low orbits (LEO). The two problems are not the same. Spacecraft charging has become widely recognized as a problem, particularly for communications satellites operating in GEO. The very thin thermal plasmas at GEO are insufficient to bleed off voltage buildups due to higher energy charged particle radiation collected on outer surfaces. Resulting differential charging/discharging causes electrical transients, spurious command signals and possible direct overload damage. An extensive NASA/Air Force program has been underway for several years to address this problem. At lower altitudes, the denser plasmas of the plasmasphere/ionosphere provide sufficient thermal current to limit such charging to a few volts or less. Unfortunately, these thermal plasma currents which solve the GEO spacecraft charging problem can become large enough to cause just the opposite problem in LEO.

  20. Ultra-compact Marx-type high-voltage generator

    SciTech Connect

    Goerz, D.A.; Wilson, M.J.

    2000-05-09

    An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

  1. Ultra-compact Marx-type high-voltage generator

    DOEpatents

    Goerz, David A.; Wilson, Michael J.

    2000-01-01

    An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

  2. Monolithic high voltage nonlinear transmission line fabrication process

    DOEpatents

    Cooper, Gregory A.

    1994-01-01

    A process for fabricating sequential inductors and varactor diodes of a monolithic, high voltage, nonlinear, transmission line in GaAs is disclosed. An epitaxially grown laminate is produced by applying a low doped active n-type GaAs layer to an n-plus type GaAs substrate. A heavily doped p-type GaAs layer is applied to the active n-type layer and a heavily doped n-type GaAs layer is applied to the p-type layer. Ohmic contacts are applied to the heavily doped n-type layer where diodes are desired. Multiple layers are then either etched away or Oxygen ion implanted to isolate individual varactor diodes. An insulator is applied between the diodes and a conductive/inductive layer is thereafter applied on top of the insulator layer to complete the process.

  3. Monolithic high voltage nonlinear transmission line fabrication process

    DOEpatents

    Cooper, G.A.

    1994-10-04

    A process for fabricating sequential inductors and varistor diodes of a monolithic, high voltage, nonlinear, transmission line in GaAs is disclosed. An epitaxially grown laminate is produced by applying a low doped active n-type GaAs layer to an n-plus type GaAs substrate. A heavily doped p-type GaAs layer is applied to the active n-type layer and a heavily doped n-type GaAs layer is applied to the p-type layer. Ohmic contacts are applied to the heavily doped n-type layer where diodes are desired. Multiple layers are then either etched away or Oxygen ion implanted to isolate individual varistor diodes. An insulator is applied between the diodes and a conductive/inductive layer is thereafter applied on top of the insulator layer to complete the process. 6 figs.

  4. Electrical safety for high voltage arrays

    NASA Technical Reports Server (NTRS)

    Marshall, N. A.

    1983-01-01

    A number of key electrical safety requirements for the high voltage arrays of central station photovoltaic power systems are explored. The suitability of representative industrial DC power switchgear for control and fault protection was evaluated. Included were AC/DC circuit breakers, electromechanical contactors and relays, load interruptors, cold disconnect devices, sectionalizing switches, and high voltage DC fuses. As appropriate, steady state and transient characteristics were analyzed. Failure modes impacting upon operation and maintenance safety were also identified, as were the voltage withstand and current interruption levels.

  5. Preliminary chaotic model of snapover on high voltage solar cells

    NASA Technical Reports Server (NTRS)

    Mackey, Willie R.

    1995-01-01

    High voltage power systems in space will interact with the space plasma in a variety of ways. One of these, snapover, is characterized by sudden enlargement of the current collection area across normally insulating surfaces generating enhanced electron current collection. Power drain on solar array power systems results from this enhanced current collection. Optical observations of the snapover phenomena in the laboratory indicates a functional relation between glow area and bia potential as a consequence of the fold/cusp bifurcation in chaos theory. Successful characterizations of snapover as a chaotic phenomena may provide a means of snapover prevention and control through chaotic synchronization.

  6. Pulsed high-voltage dc RF sputtering

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J. S., Jr.; Shaltens, R. K.

    1969-01-01

    Sputtering technique uses pulsed high voltage direct current to the object to be plated and a radio frequency sputtered film source. Resultant film has excellent adhesion, and objects can be plated uniformly on all sides.

  7. High Voltage Lines: Hazard at a Distance.

    ERIC Educational Resources Information Center

    Marino, Andrew A.; Becker, Robert O.

    1978-01-01

    It appears that a variety of biological organisms, including man, are sensitive to both long and short-term exposure to the extra low frequency electric and magnetic fields produced by high voltage lines. (BB)

  8. Detecting Faults In High-Voltage Transformers

    NASA Technical Reports Server (NTRS)

    Blow, Raymond K.

    1988-01-01

    Simple fixture quickly shows whether high-voltage transformer has excessive voids in dielectric materials and whether high-voltage lead wires too close to transformer case. Fixture is "go/no-go" indicator; corona appears if transformer contains such faults. Nests in wire mesh supported by cap of clear epoxy. If transformer has defects, blue glow of corona appears in mesh and is seen through cap.

  9. Spacecraft high-voltage power supply construction

    NASA Technical Reports Server (NTRS)

    Sutton, J. F.; Stern, J. E.

    1975-01-01

    The design techniques, circuit components, fabrication techniques, and past experience used in successful high-voltage power supplies for spacecraft flight systems are described. A discussion of the basic physics of electrical discharges in gases is included and a design rationale for the prevention of electrical discharges is provided. Also included are typical examples of proven spacecraft high-voltage power supplies with typical specifications for design, fabrication, and testing.

  10. Voltage driven magnetic bifurcations in nanomagnet-topological insulator composite structure

    NASA Astrophysics Data System (ADS)

    Semenov, Yuriy G.; Duan, Xiaopeng; Kim, Ki Wook

    2014-03-01

    Multiplicity of magnetization dynamics in thin ferromagnetic insulator (FMI) deposited on topological insulator (TI) has been studied as an effect of electron flow through the interface. The intrinsic spin polarization of TI surface current evokes the magnetization precession, which in turn modifies the TI electron spin polarization and current intensity. The net effect of this self-consistent behavior of FMI magnetization and TI surface itinerant electrons results in auto oscillations, magnetization reversal or magnetic deviation from equilibrium state according to the applied DC voltage. These phenomena are also accompanied with strong anomalous Hall effect and they are separated by the threshold voltages of magnetization bifurcations. Comparisons with spin transfer torque and spin-Hall-based mechanisms of magnetization reversal/oscillation reveal significant advantage in power efficiency of this proposed electrical control of magnetization dynamics. This work was supported, in part, by the US Army Research Office and FAME (one of six centers of STARnet, a SRC program sponsored by MARCO and DARPA).

  11. Boeing's High Voltage Solar Tile Test Results

    NASA Technical Reports Server (NTRS)

    Reed, Brian J.; Harden, David E.; Ferguson, Dale C.; Snyder, David B.

    2002-01-01

    Real concerns of spacecraft charging and experience with solar array augmented electrostatic discharge arcs on spacecraft have minimized the use of high voltages on large solar arrays despite numerous vehicle system mass and efficiency advantages. Boeing's solar tile (patent pending) allows high voltage to be generated at the array without the mass and efficiency losses of electronic conversion. Direct drive electric propulsion and higher power payloads (lower spacecraft weight) will benefit from this design. As future power demand grows, spacecraft designers must use higher voltage to minimize transmission loss and power cable mass for very large area arrays. This paper will describe the design and discuss the successful test of Boeing's 500-Volt Solar Tile in NASA Glenn's Tenney chamber in the Space Plasma Interaction Facility. The work was sponsored by NASA's Space Solar Power Exploratory Research and Technology (SERT) Program and will result in updated high voltage solar array design guidelines being published.

  12. Efficient circuit triggers high-current, high-voltage pulses

    NASA Technical Reports Server (NTRS)

    Green, E. D.

    1964-01-01

    Modified circuit uses diodes to effectively disconnect the charging resistors from the circuit during the discharge cycle. Result is an efficient parallel charging, high voltage pulse modulator with low voltage rating of components.

  13. High voltage planar multijunction solar cell

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Chai, A. T.; Goradia, C. P. (Inventor)

    1982-01-01

    A high voltage multijunction solar cell is provided wherein a plurality of discrete voltage generating regions or unit cells are formed in a single generally planar semiconductor body. The unit cells are comprised of doped regions of opposite conductivity type separated by a gap or undiffused region. Metal contacts connect adjacent cells together in series so that the output voltages of the individual cells are additive. In some embodiments, doped field regions separated by a overlie the unit cells but the cells may be formed in both faces of the wafer.

  14. Heat Transfer in High Temperature Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Miller, Steve D.; Cunnington, George R.

    2007-01-01

    High temperature multilayer insulations have been investigated as an effective component of thermal-protection systems for atmospheric re-entry of reusable launch vehicles. Heat transfer in multilayer insulations consisting of thin, gold-coated, ceramic reflective foils and Saffil(TradeMark) fibrous insulation spacers was studied both numerically and experimentally. A finite volume numerical thermal model using combined conduction (gaseous and solid) and radiation in porous media was developed. A two-flux model with anisotropic scattering was used for radiation heat transfer in the fibrous insulation spacers between the reflective foils. The thermal model was validated by comparison with effective thermal conductivity measurements in an apparatus based on ASTM standard C201. Measurements were performed at environmental pressures in the range from 1x10(exp -4) to 760 torr over the temperature range from 300 to 1300 K. Four multilayer samples with nominal densities of 48 kg/cu m were tested. The first sample was 13.3 mm thick and had four evenly spaced reflective foils. The other three samples were 26.6 mm thick and utilized either one, two, or four reflective foils, located near the hot boundary with nominal foil spacing of 1.7 mm. The validated thermal model was then used to study relevant design parameters, such as reflective foil spacing and location in the stack-up and coating of one or both sides of foils.

  15. Solar array experiments on the SPHINX satellite. [Space Plasma High voltage INteraction eXperiment satellite

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.

    1974-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations: the edge illuminated-multijunction cells, the teflon encased cells, and the violet cells.

  16. Programmable high voltage power supply with regulation confined to the high voltage section

    NASA Technical Reports Server (NTRS)

    Castell, Karen D. (Inventor); Ruitberg, Arthur P. (Inventor)

    1994-01-01

    A high voltage power supply in a dc-dc converter configuration includes a pre-regulator which filters and regulates the dc input and drives an oscillator which applies, in turn, a low voltage ac signal to the low side of a step-up high voltage transformer. The high voltage side of the transformer drives a voltage multiplier which provides a stepped up dc voltage to an output filter. The output voltage is sensed by a feedback network which then controls a regulator. Both the input and output of the regulator are on the high voltage side, avoiding isolation problems. The regulator furnishes a portion of the drive to the voltage multiplier, avoiding having a regulator in series with the load with its attendant, relatively high power losses. This power supply is highly regulated, has low power consumption, a low parts count and may be manufactured at low cost. The power supply has a programmability feature that allows for the selection of a large range of output voltages.

  17. 30 CFR 75.826 - High-voltage trailing cables.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage trailing cables. 75.826 Section 75...-Voltage Longwalls § 75.826 High-voltage trailing cables. High-voltage trailing cables must: (a) Meet existing trailing cable requirements and the approval requirements of the high-voltage continuous...

  18. 30 CFR 75.826 - High-voltage trailing cables.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false High-voltage trailing cables. 75.826 Section 75...-Voltage Longwalls § 75.826 High-voltage trailing cables. High-voltage trailing cables must: (a) Meet existing trailing cable requirements and the approval requirements of the high-voltage continuous...

  19. 30 CFR 75.826 - High-voltage trailing cables.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false High-voltage trailing cables. 75.826 Section 75...-Voltage Longwalls § 75.826 High-voltage trailing cables. High-voltage trailing cables must: (a) Meet existing trailing cable requirements and the approval requirements of the high-voltage continuous...

  20. 30 CFR 75.826 - High-voltage trailing cables.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false High-voltage trailing cables. 75.826 Section 75...-Voltage Longwalls § 75.826 High-voltage trailing cables. High-voltage trailing cables must: (a) Meet existing trailing cable requirements and the approval requirements of the high-voltage continuous...

  1. High voltage design structure for high temperature superconducting device

    DOEpatents

    Tekletsadik, Kasegn D.

    2008-05-20

    In accordance with the present invention, modular corona shields are employed in a HTS device to reduce the electric field surrounding the HTS device. In a exemplary embodiment a fault current limiter module in the insulation region of a cryogenic cooling system has at least one fault current limiter set which employs a first corona shield disposed along the top portion of the fault current limiter set and is electrically coupled to the fault current limiter set. A second corona shield is disposed along the bottom portion of the fault current limiter set and is electrically coupled to the fault current limiter set. An insulation barrier is disposed within the insulation region along at least one side of the fault current limiter set. The first corona shield and the second corona shield act together to reduce the electric field surrounding the fault limiter set when voltage is applied to the fault limiter set.

  2. New insulating materials and their use to achieve high operating stresses in electrostatic machines

    NASA Astrophysics Data System (ADS)

    Cooke, Chathan M.

    1986-02-01

    Compressed gas insulation has provided the main insulation for sustaining terminal voltages of electrostatic accelerators. Essentially coaxial geometry is used with mechanical support of the terminal achieved by long columns which also support the acceleration tubes. Because of the vacuum insulation in the acceleration tubes, the electric gradient along the columns is typically 10-20 kV/cm, whereas the radial gas gap can operate at stresses about ten times larger. Until now, the terminal support has always been located in the low stress axial direction along the column and not in the radial high stress region. This paper is concerned with support insulation to be used in the radial direction. Advantages of radial supports include: simpler, more compact column structures, higher total voltages, and support of discrete stress redistribution electrodes such as vivitron. Important factors to the design of radial support insulators include the insulation constraints imposed by the gas gap, mechanical contact to the solid insulator, and basic limits of gas-solid dielectric interfaces. The gas gap insulation strength is shown to be limited by surface microirregularities and this accounts for electrode area and pressure effects. Based on the gas gap requirements, a design strategy for the insulators is developed. Epoxy is employed as the dielectric to allow the use of cast-in metal inserts at the ends. The inserts provide mechanical contact, shielding of the triple junction, and redistribution of the interface electric stresses. By careful design, the electric stress on the interface is made lower than that in the plain coaxial electrode gap. Practical experience shows that voltage increases linearly with insulator length and that designs achieve more than 10 MV/m into the multimegavolt region.

  3. Electric breakdown effect in the current-voltage characteristics of amorphous indium oxide thin films near the superconductor-insulator transition

    NASA Astrophysics Data System (ADS)

    Cohen, O.; Ovadia, M.; Shahar, D.

    2011-09-01

    Current-voltage characteristics in the insulator bordering superconductivity in disordered thin films exhibit current jumps of several orders of magnitude due to the development of a thermally bistable electronic state at very low temperatures. In this high-resolution study we find that the jumps can be composed of many (up to 100) smaller jumps that appear to be random. This indicates that inhomogeneity develops near the transition to the insulator and that the current breakdown proceed via percolative paths spanning from one electrode to the other.

  4. Gas insulated transmission line with insulators having field controlling recesses

    DOEpatents

    Cookson, Alan H.; Pederson, Bjorn O.

    1984-01-01

    A gas insulated transmission line having a novel insulator for supporting an inner conductor concentrically within an outer sheath. The insulator has a recess contiguous with the periphery of one of the outer and inner conductors. The recess is disposed to a depth equal to an optimum gap for the dielectric insulating fluid used for the high voltage insulation or alternately disposed to a large depth so as to reduce the field at the critical conductor/insulator interface.

  5. Electro-optic high voltage sensor

    DOEpatents

    Davidson, James R.; Seifert, Gary D.

    2003-09-16

    A small sized electro-optic voltage sensor capable of accurate measurement of high voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation. A polarization beam displacer separates the input beam into two beams with orthogonal linear polarizations and causes one linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels effect elliptically polarizes the beam as it travels through the crystal. A reflector redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization. The system may include a detector for converting the output beams into electrical signals and a signal processor for determining the voltage based on an analysis of the output beams.

  6. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2001-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  7. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2004-01-13

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  8. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2000-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composite comprises a plurality of hollow oxide-based spheres of varios dimentions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substates are also provided.

  9. High-Voltage Isolation Transformer

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C. H.; Ruitberg, A. P.

    1985-01-01

    Arcing and field-included surface erosion reduced by electrostatic shields around windings and ferromagnetic core of 80-kilovolt isolation transformer. Fabricated from high-resistivity polyurethane-based material brushed on critical surfaces, shields maintained at approximately half potential difference of windings.

  10. High voltage testing for the MAJORANA DEMONSTRATOR

    NASA Astrophysics Data System (ADS)

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Chu, P.-H.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Fu, Z.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Li, A.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O'Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Snyder, N.; Suriano, A. M.; Tedeschi, D.; Thompson, A.; Ton, K. T.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.

    2016-07-01

    The MAJORANA Collaboration is constructing the MAJORANA DEMONSTRATOR, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the MAJORANA DEMONSTRATOR. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of the high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the MAJORANA DEMONSTRATOR was characterized and the micro-discharge effects during the MAJORANA DEMONSTRATOR commissioning phase were studied. A stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.

  11. High voltage testing for the Majorana Demonstrator

    DOE PAGESBeta

    Abgrall, N.; Arnquist, I. J.; Avignone, III, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Byram, D.; et al

    2016-04-04

    The Majorana Collaboration is constructing the Majorana Demonstrator, an ultra-low background, 44-kg modular high-purity Ge (HPGe) detector array to search for neutrinoless double-beta decay in 76Ge. The phenomenon of surface micro-discharge induced by high-voltage has been studied in the context of the Majorana Demonstrator. This effect can damage the front-end electronics or mimic detector signals. To ensure the correct performance, every high-voltage cable and feedthrough must be capable of supplying HPGe detector operating voltages as high as 5 kV without exhibiting discharge. R&D measurements were carried out to understand the testing system and determine the optimum design configuration of themore » high-voltage path, including different improvements of the cable layout and feedthrough flange model selection. Every cable and feedthrough to be used at the Majorana Demonstrator was characterized and the micro-discharge effects during the Majorana Demonstrator commissioning phase were studied. Furthermore, a stable configuration has been achieved, and the cables and connectors can supply HPGe detector operating voltages without exhibiting discharge.« less

  12. Compact high voltage solid state switch

    DOEpatents

    Glidden, Steven C.

    2003-09-23

    A compact, solid state, high voltage switch capable of high conduction current with a high rate of current risetime (high di/dt) that can be used to replace thyratrons in existing and new applications. The switch has multiple thyristors packaged in a single enclosure. Each thyristor has its own gate drive circuit that circuit obtains its energy from the energy that is being switched in the main circuit. The gate drives are triggered with a low voltage, low current pulse isolated by a small inexpensive transformer. The gate circuits can also be triggered with an optical signal, eliminating the trigger transformer altogether. This approach makes it easier to connect many thyristors in series to obtain the hold off voltages of greater than 80 kV.

  13. Voltage-induced recovery of dielectric breakdown (high current resistance switching) in HfO2

    NASA Astrophysics Data System (ADS)

    El Kamel, F.; Gonon, P.; Vallée, C.; Jousseaume, V.; Grampeix, H.

    2011-01-01

    Metal/HfO2/Pt stacks (where the metal is Au, Ag, Co, Ni, Cr, or In) are voltage stressed to induce a high-to-low resistive transition. No current compliance is applied during stressing (except the 100 mA limit of the voltage source). As a consequence very high conductance states are reached after switching, similar to a hard breakdown. Samples conductance after breakdown can reach up to 0.1 S, depending on the metal electrode. Despite the high postbreakdown conductance level, the samples are able to recover an insulating state by further voltage biasing ("high current resistance switching").

  14. High-voltage electrocution causing bulbar dysfunction

    PubMed Central

    Parvathy, G.; Shaji, C. V.; Kabeer, K. A.; Prasanth, S. R.

    2016-01-01

    Electrical shock can result in neurological complications, involving both peripheral and central nervous systems, which may present immediately or later on. High-voltage electrical injuries are uncommonly reported and may predispose to both immediate and delayed neurologic complications. We report the case of a 68-year-old man who experienced a high-voltage electrocution injury, subsequently developed bulbar dysfunction and spontaneously recovered. We describe the development of bulbar palsy following a significant electrical injury, which showed no evidence of this on magnetic resonance imaging. High-voltage electrocution injuries are a serious problem with potential for both immediate and delayed neurologic sequelae. The existing literature has no reports on bulbar dysfunction following electrocution, apart from motor neuron disease. PMID:27365968

  15. Next generation KATRIN high precision voltage divider for voltages up to 65kV

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Berendes, R.; Hochschulz, F.; Ortjohann, H.-W.; Rosendahl, S.; Thümmler, T.; Schmidt, M.; Weinheimer, C.

    2013-10-01

    The KATRIN (KArlsruhe TRItium Neutrino) experiment aims to determine the mass of the electron antineutrino with a sensitivity of 200 meV by precisely measuring the electron spectrum of the tritium beta decay. This will be done by the use of a retarding spectrometer of the MAC-E-Filter type. To achieve the desired sensitivity the stability of the retarding potential of -18.6 kV has to be monitored with a precision of 3 ppm over at least two months. Since this is not feasible with commercial devices, two ppm-class high voltage dividers were developed, following the concept of the standard divider for DC voltages of up to 100 kV of the Physikalisch-Technische Bundesanstalt (PTB). In order to reach such high accuracies different effects have to be considered. The two most important ones are the temperature dependence of resistance and leakage currents, caused by insulators or corona discharges. For the second divider improvements were made concerning the high-precision resistors and the thermal design of the divider. The improved resistors are the result of a cooperation with the manufacturer. The design improvements, the investigation and the selection of the resistors, the built-in ripple probe and the calibrations at PTB will be reported here. The latter demonstrated a stability of about 0.1 ppm/month over a period of two years.

  16. Potted High Voltage Modules For Space Application

    NASA Astrophysics Data System (ADS)

    Herty, Frank

    2011-10-01

    The European Space Mission GOCE, the Mercury mis- sion BepiColombo and the new High Efficiency Multistage Plasma (HEMP) thruster for the SGEO telecom mission have triggered the development of high voltage power supplies at Astrium Satellites covering different classes of output power (20W up to 1.4kW) and voltages (1kV up to 10kV). These supplies are equipped with encapsulated high voltage modules which have been designed as core functional blocks. The potting material - based on epoxy resin - was developed by Astrium Satellites. It is space-qualified for more than 30 years. Many types of high voltage modules have been manufactured since then, starting from transformer modules for the ERS mission to the modules used for electric propulsion. Technical trends, improvements and future goals of this technology are presented and discussed. New and re- fined processes are presented like the encapsulation of high-power toroidal transformers and the void-free electrical shielding by means of thin copper sheets which are laminated onto the surface of the potting material.

  17. High voltage planar multijunction. [Patent application

    SciTech Connect

    Evans, J.C. Jr.; Chai, A.T.; Goradia, C.P.

    1980-12-01

    A solar cell which provides high output voltages, comprises a semiconductor wafer in which a number or array of voltage generating regions or unit cells are formed. Each of the unit cells has two regions of opposite conductivity type (e.g., n+ and p+) which are separated by a gap region. The unit cells are connected together by metal contacts so that their outputs are additive. Field regions, separated by gaps, overlie the unit cells. Cells are formed in both faces of the wafer a circular wafer is employed. NASA

  18. DC High Voltage Conditioning of Photoemission Guns at Jefferson Lab FEL

    NASA Astrophysics Data System (ADS)

    Hernandez-Garcia, C.; Benson, S. V.; Biallas, G.; Bullard, D.; Evtushenko, P.; Jordan, K.; Klopf, M.; Sexton, D.; Tennant, C.; Walker, R.; Williams, G.

    2009-08-01

    DC high voltage photoemission electron guns with GaAs photocathodes have been used to produce polarized electron beams for nuclear physics experiments for about 3 decades with great success. In the late 1990s, Jefferson Lab adopted this gun technology for a free electron laser (FEL), but to assist with high bunch charge operation, considerably higher bias voltage is required compared to the photoguns used at the Jefferson Lab Continuous Electron Beam Accelerator Facility. The FEL gun has been conditioned above 400 kV several times, albeit encountering non-trivial challenges with ceramic insulators and field emission from electrodes. Recently, high voltage processing with krypton gas was employed to process very stubborn field emitters. This work presents a summary of the high voltage techniques used to high voltage condition the Jefferson Lab FEL photoemission gun.

  19. An Inexpensive Source of High Voltage

    ERIC Educational Resources Information Center

    Saraiva, Carlos

    2012-01-01

    As a physics teacher I like recycling old apparatus and using them for demonstrations in my classes. In physics laboratories in schools, sources of high voltage include induction coils or electronic systems that can be bought from companies that sell lab equipment. But these sources can be very expensive. In this article, I will explain how you…

  20. Recommended practices for encapsulating high voltage assemblies

    NASA Technical Reports Server (NTRS)

    Tankisley, E. W.

    1974-01-01

    Preparation and encapsulation of high voltage assemblies are considered. Related problems in encapsulating are brought out in these instructions. A test sampling of four frequently used encapsulating compounds is shown in table form. The purpose of this table is to give a general idea of the working time available and the size of the container required for mixing and de-aerating.

  1. Modular high voltage power supply for chemical analysis

    DOEpatents

    Stamps, James F.; Yee, Daniel D.

    2010-05-04

    A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  2. Modular high voltage power supply for chemical analysis

    DOEpatents

    Stamps, James F.; Yee, Daniel D.

    2008-07-15

    A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  3. Modular high voltage power supply for chemical analysis

    DOEpatents

    Stamps, James F.; Yee, Daniel D.

    2007-01-09

    A high voltage power supply for use in a system such as a microfluidics system, uses a DC--DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC--DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  4. 30 CFR 75.804 - Underground high-voltage cables.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground high-voltage cables. 75.804 Section... AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.804 Underground high-voltage cables. (a) Underground high-voltage cables used in...

  5. Highly Defective Graphene: The thinnest insulating membrane

    NASA Astrophysics Data System (ADS)

    Lherbier, Aurelien; Roche, Stephan; Restrepo, Oscar A.; Niquet, Yann-Michel; Delcorte, Arnaud; Charlier, Jean-Christophe

    2012-02-01

    The electronic structure and transport properties of two-dimensional highly defective sp2 graphene are investigated theoretically. Using classical molecular dynamics, large planes of highly defective graphene-based sheets are first generated. An accurate empirical tight-binding Hamiltonian is then elaborated, allowing the prediction of elastic mean free paths, conductivities, and charge mobilities using a real-space order-N Kubo-Greenwood method. In sharp contrast to pristine graphene, the highly defective sp2 carbon sheet displays high density of states close to the Dirac energy. However, the dynamics of the corresponding electronic wavepackets reveals extremely short mean free paths (below 1 nanometer) and quantum interferences, both yielding to particularly strong localization phenomena. Consequently, these highly defective graphene-based sheets, although exhibiting a metallic character through the density of states, are from an electronic transport perspective among the most insulating two-dimensional one-atom-thick membrane ever made.

  6. High voltage pulse generator. [Patent application

    DOEpatents

    Fasching, G.E.

    1975-06-12

    An improved high-voltage pulse generator is described which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of the first rectifier connected between the first and second capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. The output voltage can be readily increased by adding additional charging networks. The circuit allows the peak level of the output to be easily varied over a wide range by using a variable autotransformer in the charging circuit.

  7. Dynamically tracking the joule heating effect on the voltage induced metal-insulator transition in VO2 crystal film

    NASA Astrophysics Data System (ADS)

    Liao, G. M.; Chen, S.; Fan, L. L.; Chen, Y. L.; Wang, X. Q.; Ren, H.; Zhang, Z. M.; Zou, C. W.

    2016-04-01

    Insulator to metal phase transitions driven by external electric field are one of the hottest topics in correlated oxide study. While this electric triggered phenomena always mixes the electric field switching effect and joule thermal effect together, which are difficult to clarify the intrinsic mechanism. In this paper, we investigate the dynamical process of voltage-triggered metal-insulator transition (MIT) in a VO2 crystal film and observe the temperature dependence of the threshold voltages and switching delay times, which can be explained quite well based on a straightforward joule thermal model. By conducting the voltage controlled infrared transmittance measurement, the delayed infrared transmission change is also observed, further confirming the homogeneous switching process for a large-size film. All of these results show strong evidences that joule thermal effect plays a dominated role in electric-field-induced switching of VO2 crystal.

  8. High Voltage Power Supply Design Guide for Space

    NASA Technical Reports Server (NTRS)

    Bever, Renate S.; Ruitberg, Arthur P.; Kellenbenz, Carl W.; Irish, Sandra M.

    2006-01-01

    This book is written for newcomers to the topic of high voltage (HV) in space and is intended to replace an earlier (1970s) out-of-print document. It discusses the designs, problems, and their solutions for HV, mostly direct current, electric power, or bias supplies that are needed for space scientific instruments and devices, including stepping supplies. Output voltages up to 30kV are considered, but only very low output currents, on the order of microamperes. The book gives a brief review of the basic physics of electrical insulation and breakdown problems, especially in gases. It recites details about embedment and coating of the supplies with polymeric resins. Suggestions on HV circuit parts follow. Corona or partial discharge testing on the HV parts and assemblies is discussed both under AC and DC impressed test voltages. Electric field analysis by computer on an HV device is included in considerable detail. Finally, there are many examples given of HV power supplies, complete with some of the circuit diagrams and color photographs of the layouts.

  9. 30 CFR 75.804 - Underground high-voltage cables.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Underground high-voltage cables. 75.804 Section... § 75.804 Underground high-voltage cables. (a) Underground high-voltage cables used in resistance... cables shall be adequate for the intended current and voltage. Splices made in such cables shall...

  10. 30 CFR 75.804 - Underground high-voltage cables.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Underground high-voltage cables. 75.804 Section... § 75.804 Underground high-voltage cables. (a) Underground high-voltage cables used in resistance... cables shall be adequate for the intended current and voltage. Splices made in such cables shall...