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    Effect of humidity on the power frequency flashover voltage of insulators and gaps at varying temperature conditions

    Venkataraman, C.S. ; Prabhakar, B.R. ; Nandagopal, M.R.
    India, IEE-IERE Proceedings -

    Volume: 14 , Issue: 6
    DOI: 10.1049/iipi.1976.0073
    Publication Year: 1976 , Page(s): 237 - 242

    IET Journals & Magazines

    The work reported in the paper is a part of data collection on the effect of humidity on the flashover voltage of insulators and gaps at different temperature conditions. In the present investigation, studies were made at two constant temperatures of 30°C and 37°C. The corresponding humidity variations were 11 gms/m3 to 25 gms/m3 and 16 gms/m3 to 30 gms/m3 respectively. Insulators and air gaps were subjected to a power frequency voltage, under the above conditions. The results are presented through graphs. View full abstract»

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    Influence of Air Density on Flashover Voltages of Air Gaps and Insulators

    Harada, Tatsuya ; Aoshima, Yoshihide ; Ishida, Y. ; Ichihara, Y. ; Anjo, K. ; Nimura, N.
    Power Apparatus and Systems, IEEE Transactions on

    Volume: PAS-89 , Issue: 6
    DOI: 10.1109/TPAS.1970.292731
    Publication Year: 1970 , Page(s): 1192 - 1202
    Cited by:  Papers (14)

    IEEE Journals & Magazines

    Flashover tests were conducted with the cooperation of the Central Research Institute of Electric Power Industry, the Tokyo Electric Power Company, Inc., and the Chubu Electric Power Company, Inc., at the top of Mount Ny¿gasa, 1850 meters above sea level and the Takeyama Laboratory, nearly at sea level, to obtain comparative data to evaluate the influence of air density on the flashover voltages of air gaps and insulators. View full abstract»

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    Flashover behavior of semiconducting glazed insulators under positive switching impulse stress at different climatic conditions

    Elsasser, O. ; Feser, K.
    Electrical Insulation and Dielectric Phenomena, 1999 Annual Report Conference on

    Volume: 2
    DOI: 10.1109/CEIDP.1999.807904
    Publication Year: 1999 , Page(s): 711 - 714 vol.2
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper deals with the flashover voltage of semiconducting glazed insulators under positive switching impulse stress. The measurements are carried out with clean insulators. The results are compared to those obtained earlier with porcelain and composite insulators to show the benefits of the semiconducting glazed insulator technology. All tests are performed in an environmental chamber. The temperature is ranged between 10°C and 40°C in steps of 10°C. In each temperature step the relative humidity is varied between 10% and 95%. The behavior of the flashover voltage is evaluated over the relative and the absolute humidity. A temperature correction factor is given. The sole influence of the absolute humidity on the flashover voltage can be derived after applying the temperature correction to the measured values. The different flashover behavior of the semiconducting glazed insulator can be explained by its changed voltage distribution. Therefore the potential distribution along the semiconducting glazed insulator is measured with AC, DC and different impulse voltages. From the measurements and a field calculation a simple equivalent circuit is developed to calculate the potential distribution for various voltage stresses View full abstract»

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    Flashover in picture tubes and methods of protection

    Ciuciura, A.
    Radio and Electronic Engineer

    Volume: 37 , Issue: 3
    DOI: 10.1049/ree.1969.0027
    Publication Year: 1969 , Page(s): 149 - 168
    Cited by:  Papers (1)

    IET Journals & Magazines

    The aim of this paper is to bring forward and analyse phenomena occurring in a television receiver as a result of a flashover inside a picture tube, and to evolve a systematic approach to a method of protection. The paper first reviews the behaviour of a picture tube under flashover conditions, its effect on receiver circuitry, and a suggestion is made for a possible equivalent circuit. It then establishes a comprehensive method of protection against the large transients generated by a flashover which affect primarily a portion of the receiver directly connected to the base of the picture tube. This protection consists of a separate path for flashover currents, which is switched into circuit for the duration of flashover by means of spark-gaps assisted by series resistors. It is connected in such a way as to provide a minimum disturbance to the rest of the receiver. Further, the paper considers overloads imposed on the e.h.t. generator as a result of discharge of the e.h.t. capacitor by a flashover of the picture tube or other agency. Proposals are made for suitable limiters to protect the output transistor. Finally, a description of some measuring techniques of particular interest in flashover work is given. View full abstract»

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    A study of nanosecond arcsurface flashover in metallized polymer films

    Belko, V. ; Emelyanov, O. ; Shemet, M.
    Electrical Insulation and Dielectric Phenomena (CEIDP), 2013 IEEE Conference on

    DOI: 10.1109/CEIDP.2013.6747460
    Publication Year: 2013 , Page(s): 476 - 477

    IEEE Conference Publications

    Nanosecond microgap surface flashover in metalized capacitor polymer films at atmospheric air is investigated. The range of microgap is 10-1000 μm. Surface breakdown occurs between aluminum or zinc 10-20 nm thickness electrodes evaporated onto 10 μm polymer films (polypropylene, polyethylene terephthalate). The special method is used to obtain the gap size of 10-50 μm. For larger gaps the commercial capacitor segmented metallized film is used. The experimental voltage and current are measured using 2 GS/s digital oscilloscope and used for breakdown channel resistance calculation. Experimental data are analyzed on the base of known theoretical and empirical equations (Toepler, Rompe and Weizel, Vlastos, Goncharenko and others). It is shown that in the nanosecond time range Rompe and Weizel arc resistance equation is in the good agreement with experimental results. View full abstract»

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    Dielectric surface flashover in vacuum at 100 K

    Neuber, A. ; Butcher, M. ; Hatfield, L.L. ; Kristiansen, M. ; Krompholz, H.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 6 , Issue: 4
    DOI: 10.1109/94.788752
    Publication Year: 1999 , Page(s): 512 - 515
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    Cryogenic components in high power electrical systems and in power electronics gain more and more importance. The behavior of insulators for cryogenic conditions, however, is virtually unknown. In a fast coaxial setup, dielectric test sample and electrodes in vacuum are cooled to <100 K and flashover is characterized using fast electrical and optical diagnostics. Three consecutive development stages for flashover in self-breakdown mode with a gap distance of 0.5 cm can be distinguished: (1) a fast current rise to mA amplitudes within ~2 ns, probably associated with field emission, followed by, (2) a slow current rise to ~5 to 10 A amplitude with duration of 40 ns to 1 μs, associated with secondary emission avalanche saturation, and (3) a transition to a rapid gaseous ionization above the sample caused by electron induced outgassing, leading to impedance-limited current amplitudes of ⩽300 A. Phase (1) shows a higher final current at lower temperature, which is probably due to a higher initial velocity of the secondary electrons, the duration of phase (2) is a decreasing function of breakdown voltage and only slightly dependent on temperature, which points to a weak temperature dependence of the outgassing process. Flashover potentials show a slight increase at lower temperature View full abstract»

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    Impulse flashover of particle-contaminated spacers in compressed sulphur hexafluoride

    Hampton, B.F. ; Fleming, S.P.
    Electrical Engineers, Proceedings of the Institution of

    Volume: 120 , Issue: 4
    DOI: 10.1049/piee.1973.0107
    Publication Year: 1973 , Page(s): 514 - 518
    Cited by:  Papers (6)

    IET Journals & Magazines

    The impulse flashover stresses of coaxial-disc spacers, both clean and when contaminated with conducting particles, have been measured for pressures of the ambient SF6 gas between 0.47 and 1.5 MN/m2. Clean spacers had a higher flashover stress on positive than on negative polarity, but, for contaminated spacers, the positive stress was reduced much more than the negative stress. The effect of particles increased with their size over the 35¿210 ¿m range used in these experiments, and was greater at the higher gas pressures. Insulating particles of similar sizes had little effect. Experimental results followed a Gaussian distribution, and could be extrapolated to give stresses at which the flashover probability was very low. View full abstract»

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    Flashover characteristics of transformer condenser bushings

    Cole, H. L.
    Electrical Engineering

    Volume: 58 , Issue: 1
    DOI: 10.1109/EE.1939.6431737
    Publication Year: 1939 , Page(s): 27 - 34

    IEEE Journals & Magazines

    TERMINAL bushings for high-voltage power transformers require many electrical tests to demonstrate their fitness for service. A vital part of the complete transformer, they operate under extreme variations of temperature and weather conditions. They are subject to all the variations in load, ambient temperature, and surges that the transformer windings receive, and in addition must be built to withstand severe attacks of ice and snow, rain and hail, hot sun, smoke, fog, dust, and dirt. They must be stronger against flashover than the protective apparatus, and must maintain their strength year in and year out. The terminal bushing is a part of the transformer and not an individual piece of apparatus; under normal service conditions it should be proportioned in strength to the winding, and should be co-ordinated with the winding under impulse voltage conditions. View full abstract»

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    Insulator performance studied by flashover tests

    Frey, H.A. ; Hawley, K.A.
    Electrical Engineering

    Volume: 51 , Issue: 7
    DOI: 10.1109/EE.1932.6429907
    Publication Year: 1932 , Page(s): 505

    IEEE Journals & Magazines

    Many factors affect the flashover characteristics of porcelain insulators; these characteristics in turn have a direct bearing upon insulator design and upon the choice of proper insulation for any particular purpose. In the following group of three articles by representatives of three of the leading insulator manufacturers, results of investigations made in this field by these manufacturers are given. In the past, many of the data for comparable insulators from different sources seemed conflicting. In these articles, however, reasonably careful study will reveal many points of agreement, when the results are reduced to a comparable basis. The first two articles deal with the effect of various factors on insulator sparkover characteristics; the third article deals with the flashover characteristics of suspension insulators, and also contains data relating to the cost and selection of economical suspension insulator assemblies. View full abstract»

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    The application of digital image processing technology in studying composite insulator pollution flashover

    Hongqi Zhang ; Chunguang Wang ; Haizhen Kang
    Signal Processing Systems (ICSPS), 2010 2nd International Conference on

    Volume: 3
    DOI: 10.1109/ICSPS.2010.5555813
    Publication Year: 2010 , Page(s): V3-538 - V3-540

    IEEE Conference Publications

    This article introduces the idea of utilizing computer-based image processing technology to conduct precise and objective composite insulator testing. The methods that are most commonly used in testing composite insulators are reviewed. Image-based analysis of hydrophobic insulator classification systems is explored. In conclusion, the author introduces image processing technology into the testing of hydrophobicity of composite insulators. View full abstract»

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    Switching-surge flashover characteristics of long sphere-plane gaps for UHV station design

    Schneider, H.M. ; Turner, F.J.
    Power Apparatus and Systems, IEEE Transactions on

    Volume: 94 , Issue: 2 , Part: 1
    DOI: 10.1109/T-PAS.1975.31883
    Publication Year: 1975 , Page(s): 551 - 560
    Cited by:  Papers (10)

    IEEE Journals & Magazines

    The switching-surge behavior of UHV station electrodes was studied by investigating the performance of sphere-plane gaps. Design curves which show the effect of electrode curvature on the critical flashover voltage for spheres ranging in diameter from 0.5 to 2.5 meters and with gap spacings between 1 and 11 meters are presented. The influence of waveshape on large electrode flashover characteristics was obtained by varying the time-to-crest of the applied waveforms between 75 and 1220 µs. Test data are given for smooth and segmented spheres during dry conditions. The effect of precipitation on the switchlng-surge strength was investigated by wetting the sphere surfaces either by natural rain or artificial means. The results presented provide information required for the switchlng-surge design of outdoor UHV stations. View full abstract»

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    Degradation of cross linked polystyrene by repetitive impulse surface flashovers in vacuum

    Shengtao Li ; Weiwang Wang ; Shihu Yu ; Jianying Li
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 20 , Issue: 5
    DOI: 10.1109/TDEI.2013.6633727
    Publication Year: 2013 , Page(s): 1934 - 1941

    IEEE Journals & Magazines

    In order to understand aging mechanism of solid insulating materialscaused by surface flashover, this paper presents the electrical degradation characteristics of cross linked polystyrene (XLPS) by repetitive impulse surface flashovers in vacuum. The surface of samples underwent flashover repeatedly under different impulse voltage situations. Each flashover voltage and current was recorded, and the flashover energy was calculated to present flashover properties under each condition. Experimental results indicate that there are different degradation phenomena of XLPS after undergoing those impulse flashovers. The flashovers with small current have positive effect on surface flashover property of insulating material. However, the large currents when flashovers occurred play a destruction role in surface properties of XLPS. It is said that finite numbers of repetitive impulse flashovers under small flashover currents removed the contaminants, water and gas on the sample surface. In addition, it represents a "conditioning" effect and stable situation of flashover properties under these situations due to removal of emission sites, micro protuberance of electrodes and sample surface, especially at the cathode triple junction. However, repetitive flashovers under high flashover current (≫1 kA) led to surface degradation. This phenomena attributes to the high flashover energy changed the sample surface state, destroyed the sample surface and formed apparent carbonized channels and regions on sample surface. So flashover becomes unstable in this situation. Through summarizing and analyzing the experimental results, the flashover energy was proposed as a main factor to characterize the phenomenon of degradation by repetitive impulse flashovers in vacuum. View full abstract»

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    The Effect of X‐Rays on the Breakdown Strength and Flashover Voltage of Certain Dielectrics

    Walker, Eric A.
    Journal of Applied Physics

    Volume: 12 , Issue: 3
    DOI: 10.1063/1.1712897
    Publication Year: 1941 , Page(s): 215 - 218

    AIP Journals & Magazines

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    Comparison of DC Pollution Flashover Performances of Various Types of Porcelain, Glass, and Composite Insulators

    Xingliang Jiang ; Jihe Yuan ; Lichun Shu ; Zhijin Zhang ; Jianlin Hu ; Feng Mao
    Power Delivery, IEEE Transactions on

    Volume: 23 , Issue: 2
    DOI: 10.1109/TPWRD.2007.908779
    Publication Year: 2008 , Page(s): 1183 - 1190
    Cited by:  Papers (15)

    IEEE Journals & Magazines

    Based on the artificial pollution tests, the flashover performance of various types of DC porcelain and glass suspension insulators as well as composite long-rod insulators were analyzed and compared. The test results show that there is a nearly linear relation between the pollution flashover voltage and the disc-type insulator string length. The flashover voltage gradients of the insulators are affected by their materials and shed shapes. The antipollution performances of glass insulators are superior to those of porcelain insulators with the same profile. The flashover voltage gradients of composite insulators are higher than those of porcelain or glass ones. The exponent characterizing the influence of salt deposit density on the pollution flashover voltage is dependent on the profile and the material of insulators, and the values of the composite insulators' exponents are smaller than those of porcelain or glass insulators, namely, the influence of the pollution on the composite insulators is relatively less. The effectiveness of leakage distances of porcelain or glass insulators is less than 0.9 while that of composite insulators is higher than 0.9. View full abstract»

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    Enhancement of high voltage Electron Beam Welding power supply: Rapid recovery after flashover detection for void-free welding

    Parthipan, Thayaparan ; Ribton, Colin ; Mudge, Peter ; Nilavalan, Rajagopal. ; Balachandran, Wamadeva
    Industrial Electronics (ISIE), 2013 IEEE International Symposium on

    DOI: 10.1109/ISIE.2013.6563804
    Publication Year: 2013 , Page(s): 1 - 6

    IEEE Conference Publications

    An Electron Beam Welding power-source was analyzed using system modeling techniques for implementing hardware changes. Fault recovery control circuits for flashover detection and system stability were analyzed. Simulation results obtained revealed the possibility of enhancing the system and further work is required to implement the identified parameters in the real hardware for welding trials. View full abstract»

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    Influence of surface charge on DC flashover characteristics of epoxy/BN nanocomposites

    Du, B.X. ; Meng Xiao
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 21 , Issue: 2
    DOI: 10.1109/TDEI.2013.004137
    Publication Year: 2014 , Page(s): 529 - 536

    IEEE Journals & Magazines

    Epoxy is widely used in electronic and electrical devices because of its excellent insulation properties. The addition of nanoparticles to epoxy could change the material structure and then charge behaviors are altered as a consequence. The accumulation of surface charge may cause electric field distortion, which would lead to surface flashover. In this paper, the samples were made by dispersing nano-scale boron nitride (BN) particles in Epoxy with the weight ratios of 5, 10, 20, 30, 40 wt%. The samples were charged by a dc corona triode system using needle-plate electrodes. The distribution of charges was measured with an electrostatic voltmeter and the effect of nanoparticles on charge accumulation and decay behavior was studied. A flashover test was carried out under a dc stress between two finger-type electrodes. The effect of nanoparticles on flashover characteristics and the relation between surface charging and surface flashover were also investigated. The results showed that the traps between nanoparticles and the polymer, which were introduced by the added nanoparticles, could cause surface charge accumulation. In addition, the flashover occurred at a lower voltage because of the accumulated charge on the sample surface. View full abstract»

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    Flashover to a resin bonded carbon fibre fishing rod from an overhead power line: doubt about the mechanism

    Norris, W.T.
    High Voltage Engineering, 1999. Eleventh International Symposium on (Conf. Publ. No. 467)

    Volume: 2
    DOI: 10.1049/cp:19990660
    Publication Year: 1999 , Page(s): 333 - 336 vol.2

    IET Conference Publications

    The question is raised whether breakdown to a carbon fibre fishing rod held a few metres from an overhead 33 kV power line might occur as the result of the discharge of accumulated charge on the rod arising from a rectifying action. The discharge might provoke muscular contraction in the person holding the rod so that the rod was sharply brought into contact with the energised conductors. Or perhaps the discharge might trigger long distance breakdown through the air View full abstract»

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    The influence of experimental method on the flashover performance of alumina in vacuum

    Lijian Ding ; Li, C.R. ; Youping Tu ; Jinzhuang Lu ; Rui Li
    Electrical Insulation and Dielectric Phenomena, 2003. Annual Report. Conference on

    DOI: 10.1109/CEIDP.2003.1254857
    Publication Year: 2003 , Page(s): 317 - 320

    IEEE Conference Publications

    This paper presented some new experimental results observed in our investigation. Based on the experiments, it was found that the different voltage application sequence on the test samples could influence the flashover voltage of the tested samples. Three kinds of voltage application sequences were compared and three kinds of alumina samples were involved in this paper. In general, the flashover voltage is the lowest if the applied voltage started from a lower voltage (-2 kV) at a -2 kV step; the flashover voltage could be the highest if the applied voltage started from -22 kV. The surface charge distributions were observed after the voltage was applied. According to the experimental results, the change of the flashover voltage of the test samples could be attributed to the state of surface charge distribution with different voltage application sequence. View full abstract»

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    Monte Carlo based simulation on surface charging phenomena of insulators prior to flashover in vacuum

    Kai-kun Yu ; Huang, Xue-Zeng ; Nan Zheng ; Guan-Jun Zhang ; Yamano, Y. ; Kobayashi, S.
    Discharges and Electrical Insulation in Vacuum (ISDEIV), 2010 24th International Symposium on

    DOI: 10.1109/DEIV.2010.5625796
    Publication Year: 2010 , Page(s): 109 - 112

    IEEE Conference Publications

    As we know, before flashover across an insulator surface under high electric field in vacuum, there are charging phenomena occurring on the insulator surface, which significantly affect the developing process of flashover. Based on the secondary electron emission avalanche (SEEA) model, and by using the Monte Carlo method, a two-dimensional analysis of surface charge density on cylindrical and conical insulators prior to flashover in vacuum has been performed under unipolar voltage. Typical insulating materials are employed, i.e., machinable ceramic, alumina ceramic, PTFE and PMMA. The influences of secondary electron yield, voltage amplitudes and coning angles on charge distribution are investigated. The results reveal that negative charges exist in a small surface region near the cathode, while the surface charges positive in a larger region away from the cathode. With increasing applied voltage, both the negative charge density and region decrease, and even vanish, whereas both the positive charge density and region increase, and the peaks of both regions move towards the cathode. View full abstract»

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    Influence of the linear non-uniformity of pollution layer on the insulator flashover under impulse voltage - estimation of the effective pollution thickness

    Slama, M.E. ; Beroual, A. ; Hadi, H.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 18 , Issue: 2
    DOI: 10.1109/TDEI.2011.5739441
    Publication Year: 2011 , Page(s): 384 - 392
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    This paper is aimed at the influence of the linear non uniformity of pollution layer on critical current Icri and critical flashover voltage Vcri of polluted insulator under lightning impulse voltage. It is shown that the experimental values of Icri and Vcri of uniformly and non-uniformly polluted insulator depends on the configuration of pollution and the polarity of voltage. A mathematical model enabling to compute the flashover discharge characteristic constants (n and N) and the critical thickness of pollution layer and thence the critical characteristics of flashover (current and voltage) is presented. It's also shown that n and N are not static and they depend on the parameters of the equivalent electrical circuit, thermal characteristics of discharge and the condition of propagation. The computed critical voltages are found in a good accordance with the experimental ones while the computed critical currents are higher than the experimental ones. The recalculated critical currents and critical voltages assuming that only a part of the thickness of pollution layer contributes to the conduction phenomena at the interface between the discharge and electrolyte well match to the experimental values. Thus there is an effective thickness of pollution layer which varies linearly with the resistivity of pollution layer. View full abstract»

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    An experimental investigation into the repetitive breakdown and flashover properties of insulating tubes and films

    McPhee, A.J. ; Tidmarsh, J.R. ; MacGregor, S.J.
    Pulsed Power '96, IEE Colloquium on

    DOI: 10.1049/ic:19960375
    Publication Year: 1996 , Page(s): 1/1 - 1/5
    Cited by:  Papers (1)

    IET Conference Publications

    Many pulsed power and high voltage systems incorporate coaxial oil insulated transmission lines capable of withstanding voltages in excess of 100 kV. The aim of this test programme was to investigate the material limits of solid dielectric insulation at such potentials. Although this can lead to catastrophic failure it can also result in an increased line capacitance and with the correct choice of dielectric it may be possible to operate with increased energy levels and reduced system volumes. This test programme addresses the electrical breakdown characteristics of various materials for pulses representative of those generated in a typical high voltage transmission line system. The broad aims of this test programme were to: compare the flashover and breakdown performance of different materials in air and in oil; compare the voltage characteristics of insulating tubes and insulating films for different materials; and investigate the effect of repetitive operation and pulse charging upon solid insulation View full abstract»

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    Flashover Characteristic of Epoxy Composites Filled With Different Micro-Inorganic Oxide Particles Under Nanosecond Pulse in Vacuum

    Chen, Yu ; Yonghong Cheng ; Kai Wu ; Nelson, J.K. ; Dissado, L.A. ; Shengtao Li
    Plasma Science, IEEE Transactions on

    Volume: 37 , Issue: 1
    DOI: 10.1109/TPS.2008.2005674
    Publication Year: 2009 , Page(s): 195 - 203
    Cited by:  Papers (6)

    IEEE Journals & Magazines

    Research on the vacuum surface flashover mechanisms of insulating material under nanosecond pulses is important for the design and manufacture of high-power pulse generators. Here, the vacuum surface flashover characteristic of epoxy composites filled with different microfillers Al2O3 middot3H2O , Al2O3, BaTiO3, and TiO2 is investigated using a unipolar pulse generator (50-ns rise time and 600-ns full-width at half-maximum). In addition, their thermally stimulated depolarization current and secondary electron emission (SEE) coefficients are measured. The results show that the flashover performance does not depend just on the SEE coefficient, but that the different effects of shallow and deep traps must also to be taken into account. View full abstract»

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    Estimation of flashover probability of aged nonceramic insulators in service

    Montesinos, J. ; Gorur, R.S. ; Burnham, J.
    Power Delivery, IEEE Transactions on

    Volume: 15 , Issue: 2
    DOI: 10.1109/61.853025
    Publication Year: 2000 , Page(s): 820 - 826
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    A procedure for estimating the flashover probability of aged nonceramic insulators in-service is presented. The study was carried out using two types of 138 kV EPDM line post insulators received from the Florida Power and Light system (USA). Presented are the laboratory characterization of the naturally contaminated insulators, the development of a linear regression model, and the estimation of the statistical parameters that define the relation between probability of failure and applied voltage for a given contamination level. The results obtained in the laboratory were in agreement with the current and past field experience. Conservative probabilities of flashover were estimated under the assumption of a cumulative normal distribution. The estimators of the parameters that define the normal distribution were assessed with the original up and down method. The results suggest that for one type of EPDM insulator, contamination flashover performance was distinctly inferior to the other View full abstract»

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    Discussion on flashovers of air-gaps and insulators


    Electrical Engineers, Proceedings of the Institution of

    Volume: 110 , Issue: 11
    DOI: 10.1049/piee.1963.0288
    Publication Year: 1963 , Page(s): 2016 - 2022

    IET Journals & Magazines

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    Influence of Humidity on Lightning and Switching Impulse Flashover Voltages

    Harada, Tatsuya ; Aihara, Yoshinori ; Aoshima, Yoshihide
    Power Apparatus and Systems, IEEE Transactions on

    Volume: PAS-90 , Issue: 4
    DOI: 10.1109/TPAS.1971.293127
    Publication Year: 1971 , Page(s): 1433 - 1442
    Cited by:  Papers (16)

    IEEE Journals & Magazines

    A long run flashover test was carried out from 1967 to 1969 to investigate the effect of atmospheric humidity on lightning and switching 50-percent flashover voltages of air gaps and suspension insulators. From the test results, it was found that the influence of humidity on flashover voltages of air gaps varied greatly from their flashover voltage-gap length characteristics. View full abstract»

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    The Effect of Nano-scale SiO2 on the Flashover Voltage of Epoxy/ SiO2 Nanocomposite

    Du, B.X. ; Jie Li ; Meng Xiao ; Zhang, J.W. ; Guo, Y.G.
    Electrical Insulating Materials (ISEIM), Proceedings of 2011 International Conference on

    Publication Year: 2011 , Page(s): 466 - 469

    IEEE Conference Publications

    Epoxy insulator has been widely used in railway transmission line due to its excellent physical and chemical properties. On these transmission lines, corona could occur even on well designed hardware and insulators, which can inject the charge in the surface of insulators and damage the polymer insulators. When a composite insulator is moistened by fog or rain, charged water droplets are formed on the surface, which may affect the insulation performance. Recently a number of papers have reported enhanced electrical (aging and breakdown) performance of Epoxy/SiO2 nanocomposite, but little attention has been focused on the performance of water droplets on a polymer nanocomposite surface with corona discharge. This research investigates the dynamic behavior of charged water droplets on the surface of Epoxy/SiO2 nanocomposite. The samples were made by dispersing nano-scale SiO2 powdered in epoxy with the weight ratios of 1, 3, 5, 7 wt%, and were put under needle electrodes for 5 minutes before the test. Then the experiment was carried out under a dc stress between two aluminum plate electrodes. The initial surface flashover voltage was recorded during the experiments. The results indicate the relationship between the quantity charge of the water droplet and the initial flashover voltage via the charged water droplet. We get the conclusion that the greater charge quantity, the higher flashover voltage. View full abstract»

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    Suspension Insulator Flashover under High Impulse Voltages

    Kingsbury, B.E.
    Power Apparatus and Systems, Part III. Transactions of the American Institute of Electrical Engineers

    Volume: 76 , Issue: 3
    DOI: 10.1109/AIEEPAS.1957.4499811
    Publication Year: 1957 , Page(s): 1429 - 1432
    Cited by:  Papers (12)

    IEEE Journals & Magazines

    First Page of the Article
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    Energy Balance of Highly Contaminated Surface Flashover on Thin Films

    Halstead, E.M. ; Buneo, J.D. ; Sarjeant, W.J. ; Singh, H.
    Pulsed Power Conference, 2005 IEEE

    DOI: 10.1109/PPC.2005.300461
    Publication Year: 2005 , Page(s): 990 - 992

    IEEE Conference Publications

    The ability to produce controllable plasmas is usually confined to high energy applications. Many applications, however, would greatly benefit from a reduction of this input energy. This paper examines a new, low energy method to generate a plasma utilizing the mechanism of surface flashover on thin metallized films. This method of plasma generation was unique in that a controllable plasma was generated while requiring less than 5 J of energy. The plasma was produced by applying an impulse voltage of 2.5 kV to a sample of polypropylene film coated with an aluminum metallization on one surface. The resultant flashover liberated only a small percentage of the metallization off of the polypropylene film. The energy required to create the plasma was determined by evaluating the time integral of the voltage and current product then comparing that quantity to the amount of energy required to liberate the already removed aluminum metallization from the polypropylene film. It was found that the energy required to vaporize the aluminum was about an order of magnitude less than the total amount of energy that went into the film. After taking this into account, the amount of energy required to generate and sustain the plasma was determined. This low energy plasma initiation could have interesting applications as a low power light source or be exploited for other avenues of inquiry. View full abstract»

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    Anomalous Flashovers on Transmission Lines [includes discussion]

    Miller, C.J.
    Power Apparatus and Systems, Part III. Transactions of the American Institute of Electrical Engineers

    Volume: 75 , Issue: 3 , Part: III
    DOI: 10.1109/AIEEPAS.1956.4499381
    Publication Year: 1956
    Cited by:  Papers (18)

    IEEE Journals & Magazines

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    Effects of Voltage Gradient Distribution on External Flashovers of Polluted Outdoor High Voltage Power Plant

    Alame, N. ; Shihab, S.
    Athens Power Tech, 1993. APT 93. Proceedings. Joint International Power Conference

    Volume: 1
    DOI: 10.1109/APT.1993.686843
    Publication Year: 1993 , Page(s): 57 - 60
    Cited by:  Papers (1)

    IEEE Conference Publications

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    Surface flashover and preflashover phenomena of solid dielectrics in vacuum

    Sudarshan, T.S.
    Discharges and Electrical Insulation in Vacuum, 1996. Proceedings. ISDEIV., XVIIth International Symposium on

    Volume: 1
    DOI: 10.1109/DEIV.1996.545386
    Publication Year: 1996 , Page(s): 381 - 390 vol.1

    IEEE Conference Publications

    A lateral test structure with metalized film electrodes is shown to have distinct advantages over a conventional solid electrode structure for studying the HV characteristics of solid insulators in vacuum. The paper presents results of streak photography and spectral analysis of surface discharge luminosity, and of preflashover activity using time-coordinated current, luminosity, and imaging. The preflashover consisting of bursts of time-correlated current and light emission, is associated with randomly distributed emission spots on the surface. It is proposed that the above observations are related to charge trapping and detrapping processes at localized energy levels associated with insulator surface defects View full abstract»

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    The vacuum flashover characteristics of dielectrics under ns pulse

    Junping, Tang ; Qiu Aici ; Chen Yu ; Cheng Yonghong ; Li, Yang ; Ying, Sun ; Chen Weiqing ; Wei, Jia
    Solid Dielectrics, 2007. ICSD '07. IEEE International Conference on

    DOI: 10.1109/ICSD.2007.4290918
    Publication Year: 2007 , Page(s): 733 - 736

    IEEE Conference Publications

    The solid dielectrics such as epoxy, high density polyethylene(HDPE), polytetrafluoroethylene (PTFE), nylon and polymethylmethacrylate(PMMA) are often used as vacuum insulator in pulsed power device, in which they were applied under pulse voltage with risetime from several to several tens nanoseconds. Flashover characteristics must be paying more attention because they are the major breakdown models in their applications. A pulse source with output voltage of 50 ns risetime, 320ns pulse width and peak voltage up to 200 kV has been developed in this research. The flashover characteristics including flashover voltage and flashover current of the materials mentioned above under plane electrode were tested under 5E-3Pa vacuum. In order to get the relationship between surface charge deposition and the flashover characteristics, the surface potential distribution before flashover and after once, seventh and thirty-fifth flashovers are presented in this paper. View full abstract»

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    Steep front impulse flashover tests on a solid-state relay

    Salas, T.M. ; Wiggins, C.M. ; Barnes, P.R.
    Power Delivery, IEEE Transactions on

    Volume: 5 , Issue: 3
    DOI: 10.1109/61.57967
    Publication Year: 1990 , Page(s): 1281 - 1287
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    A protective relay system, subjected to a high-voltage, steep-front impulse, has been shown to fail in the laboratory via flashover-induced current follow through on the DC power supply. Laboratory experiments were performed to characterize the response of a protective relay to steep-front impulses. These impulses may be the result of a nuclear-induced, high-altitude electromagnetic pulse. Tests were also conducted to quantify the protection offered by a surge protection package on the DC circuits of a relay system. Results from these tests were used to assess the vulnerability of a protective relay View full abstract»

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    Room flashover and subsequent filling of the structure with smoke

    Lilley, D.G.
    Energy Conversion Engineering Conference, 2002. IECEC '02. 2002 37th Intersociety

    DOI: 10.1109/IECEC.2002.1392022
    Publication Year: 2002

    IEEE Conference Publications

    This work describes room flashover and subsequent filling of the structure with smoke. Modeling of the progress of the smoke is possible with a variety of available computer codes, thus permitting calculations of temperature and smoke level in different rooms as time progresses. The CFAST computer code (Consolidated model of Fire growth And Smoke Transport) is used to calculate temperatures and smoke levels in the various rooms of the house initially. Experimental work assists in understanding fire behavior in structural fires. View full abstract»

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    Dielectric surface flashover in vacuum at cryogenic temperature (100 K)

    Neuber, A. ; Krompholz, H. ; Hatfield, L.L.
    Electrical Insulation and Dielectric Phenomena, 1997. IEEE 1997 Annual Report., Conference on

    Volume: 2
    DOI: 10.1109/CEIDP.1997.641139
    Publication Year: 1997 , Page(s): 575 - 578 vol.2
    Cited by:  Papers (4)

    IEEE Conference Publications

    Recent developments in high power systems use cryogenic components, where the performance of insulators at such low temperatures is unknown. In a fast coaxial setup, electrodes and dielectric sample are cooled to less than 100 K in vacuum, and the flashover initiation processes for gap distances on the order of 1 cm are characterized using fast electrical and optical diagnostics. As reported before, two development stages can be distinguished: a first phase with slowly rising current and the presence of free electrons, with a duration of 10-50 ns, and a second stage with a fast current rise due to gaseous ionization and collision dominated electrons. First experiments comparing cooled samples and samples at room temperature do not show discernible differences for Lexan. For Alumina, however, an increase of the duration of phase 1 is observed, with a higher current amplitude at the transition from phase one to phase two. Also, the current rise in phase two is reduced. These results indicate a temperature dependence of the electron induced outgassing process which is expected to cause the transition from phase one to phase two View full abstract»

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    DC Flashover Voltage Characteristics and Their Calculation Method for Oil-Immersed Insulation Systems in HVDC Transformers

    Kurita, A. ; Takahashi, E. ; Ozawa, J. ; Watanabe, M. ; Okuyama, K.
    Power Engineering Review, IEEE

    Volume: PER-6 , Issue: 7
    DOI: 10.1109/MPER.1986.5527867
    Publication Year: 1986 , Page(s): 51 - 52
    Cited by:  Papers (2)

    IEEE Journals & Magazines

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    Flashover due to lightning of composite insulators used on distribution line

    Izzularab, M.A. ; Shwehdi, M.H. ; Farag, A.S. ; Belhadj, C.A.
    Electrical Insulation, 1998. Conference Record of the 1998 IEEE International Symposium on

    Volume: 2
    DOI: 10.1109/ELINSL.1998.694817
    Publication Year: 1998 , Page(s): 395 - 398 vol.2

    IEEE Conference Publications

    The problem of estimating lightning insulation strength of distribution line designs is complicated due to numerous factors. In general, classical techniques that account for air gap flashover do not apply. The fundamental reasons for these complications are still not precisely reported. Some researchers relate them to small distances between electrodes, others to the presence of wood insulation, insulator size, hardware size, shape, position of components, multiple arc paths, and probably not seen other factors. In this paper modern insulation materials used on distribution systems such as porcelain, fiber-glass reinforced plastics (FRP) and polymers and their composite combinations are considered. The study takes into account, not only the configuration of the composite insulators, but also the point of incidence of the lightning impulse that may cause flashover and location of grounding wires. The paper presents an empirical factor to estimate the flashover voltage due to lightning of composite insulators used on distribution overhead lines. The physical and the active length of composite insulators are also determined to evaluate the most effective configuration and material to be used. Factors that may affect the critical flashover voltage (CFO) of composite insulators are investigated and defined to evaluate different insulator types and material composites used. Physical explanations of the mathematical models are discussed to validate such a model View full abstract»

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    Influence of surface ion exchange on pulsed flashover characteristics of machinable ceramics in vacuum

    Nan Zheng ; Guan-Jun Zhang ; Huang, Xue-Zeng ; Peng Zhai ; Xin-Pei Ma ; Guang-Xin Li
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 18 , Issue: 4
    DOI: 10.1109/TDEI.2011.5976089
    Publication Year: 2011 , Page(s): 1011 - 1016

    IEEE Journals & Magazines

    For pulsed power devices, the surface flashover across their solid insulation becomes a serious problem. Investigators have paid much attention on improving the surface electric withstanding strength of insulator. It is found that surface treatment is very useful to increase the surface flashover voltage. The flashover phenomena along machinable ceramics (MCs) are investigated under pulsed voltage in vacuum. The ion exchange method is used to adjust the surface components of MCs for improving its surface electric strength. CuSO4 is used for ion exchanging with the MC. It is found that ion exchange treatment greatly changes the surface components and microstructure of MCs, which has obvious influence on flashover characteristics of MCs. The MCs with 10 h ion-exchange time show a much improved flashover holdoff. Based on the secondary electron emission avalanche (SEEA) theory, the improvement of flashover withstanding ability can be reasonably explained by electron impact and transport behaviors. View full abstract»

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    Experimental investigation of the flashover problem at the XLPE cable terminations under coastal environments

    El-Dessouky, S.S. ; Rasmi, A.A. ; Youssef, F.M.H.
    Electrical Insulation, 1990., Conference Record of the 1990 IEEE International Symposium on

    DOI: 10.1109/ELINSL.1990.109742
    Publication Year: 1990 , Page(s): 208 - 212

    IEEE Conference Publications

    Coastal environments can drastically raise the flashover probability at XLPE (cross-linked polyethylene) cable terminations. The authors report on a field study and experimental investigations of this flashover phenomenon for the 12/2-kV XLPE cables used in Egypt. The influence of sharp-edge shield or smooth shield of termination, the axial longitudinal distance of termination, tape insulation, and the number of tape layers on the termination disruptive corona voltage and flashover voltage have been investigated and analyzed. Important guidelines toward an optimum treatment of cable terminations have been derived from the experiments. In particular, it is noted that the disruptive corona voltage can be taken as the main parameter affecting the design of the cable termination profile. The breakdown voltage per tape layer is not constant; the first four tape layers have higher electric stress. The effect of sharp-edge shield and high radial stress can be improved by lapping four layers of an insulation tape on the first five centimetres of the longitudinal axial distance. The increase of the longitudinal distance improves the effect of wet conditions and this is suitable for outdoor termination at normal humid conditions View full abstract»

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    Displacement current and surface flashover

    Harris, J.R. ; Caporaso, G.J. ; Blackfield, D. ; Chen, Y.-J.
    Applied Physics Letters

    Volume: 91 , Issue: 12
    DOI: 10.1063/1.2785116
    Publication Year: 2007 , Page(s): 121504 - 121504-3
    Cited by:  Papers (3)

    AIP Journals & Magazines

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    A lithium‐fluoride flashover ion source cleaned with a glow discharge and irradiated with vacuum‐ultraviolet radiation

    Burns, E.J.T. ; Woodworth, J.R. ; Bieg, K.W. ; Mehlhorn, T.A. ; Stygar, W.A. ; Sweeney, M.A.
    Journal of Applied Physics

    Volume: 63 , Issue: 1
    DOI: 10.1063/1.340501
    Publication Year: 1988 , Page(s): 11 - 27
    Cited by:  Papers (4)

    AIP Journals & Magazines

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    Improved Vacuum Surface Flashover Performance Of Polymer Insulators By The Use Of Unique Triple Junction Designs

    Smith, J.D. ; Kahaian, D.J. ; Honig, E.M. ; Montoya, R.E. ; Rosocha, L.A. ; Allen, G.R.
    Pulsed Power Conference, 1991. Digest of Technical Papers. Eighth IEEE International

    DOI: 10.1109/PPC.1991.733423
    Publication Year: 1991 , Page(s): 882 - 885
    Cited by:  Papers (2)

    IEEE Conference Publications

    Previous research and theories about surface flashover in vacuum indicate that the triple junction region plays a critical role in the insulator flashover process. To attempt to improve upon the performance of the standard 45-degree frustum insulator, three different insulator geometries with modified triple junction regions were investigated. Two samples of each geometry, each 2 cm thick, were tested to obtain the flashover voltage levels in a low 10/sup -5/ Torr vacuum using a 1.2- microsecond risetime voltage pulse. Each sample was tested five times with 20 shots per test for a total of 200 shots per geometry. Test results and comparisons of the flashover voltage levels for the four geometries are presented. One geometry showed an improvement in flashover voltage of about 40% over the standard 45-degree frustum. It also showed significantly less susceptibility to low-voltage flashover due to surface damage, suggesting a correlation between surface damage and the development of conductive paths along the surface. View full abstract»

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    Using of pulse high-voltage dielectric flashover for formation of REB with super-short front for high-power MW generators

    Galstjan, E.A. ; Kazanskiy, L.N.
    Discharges and Electrical Insulation in Vacuum, 1998. Proceedings ISDEIV. XVIIIth International Symposium on

    Volume: 2
    DOI: 10.1109/DEIV.1998.738830
    Publication Year: 1998 , Page(s): 645 - 648 vol.2

    IEEE Conference Publications

    Existing high-power accelerators could not generate relativistic electron beams (REB) with the required parameters as follows: 1-2 MeV, 10-20 kA, 200-300 ns and, at the same time, with the front rise time of the order of or less 1 ns. It is determined by the physical restrictions in the vacuum insulator of a diode of a high-power accelerator. In view of this fact, final front shortening has to take place in the vacuum part of the high-voltage diode. It needs a very fast switch for REB commutation. From the point of view of simplicity, use of dielectric flashover as a very fast and stable process is put in perspective for this purpose. One attempt in this direction was made by the Moscow Radiotechnical Institute by using of the electromagnetic shock wave formation phenomenon taking place in the cathode line with a sufficiently long dielectric insert. REB's front shortening from 10-15 ns up to a value of 1-1.5 ns has obtained experimentally. So a kind of REB could not be used directly in usual high-power MW generators with an external magnetic field. For this reason, the authors suggest the use of a two-beams cathode as a source of the REB with very short front duration (1 ns or less). For this purpose, the secondary beam is delayed for the front duration of the primary beam by means of some dielectric surface discharger. The primary beam is captured by a collector and the secondary is utilized in a MW generator. In this report, the authors show the theoretical ground in detail and discuss an experimental verification of this idea View full abstract»

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    Pulsed Flashover of Insulators in Vacuum

    Milton, O.
    Electrical Insulation, IEEE Transactions on

    Volume: EI-7 , Issue: 1
    DOI: 10.1109/TEI.1972.299183
    Publication Year: 1972 , Page(s): 9 - 15
    Cited by:  Papers (56)

    IEEE Journals & Magazines

    Dielectric specimens in the shape of a frustum of a cone were evaluated for surface flashover strength in vacuum of 10-5 torr. Data were obtained for positive and negative pulses of several hundred kilovolts amplitude and with rise times in the nanosecond and microsecond region. The results indicate that most materials exhibit a greater resistance to breakdown if the base of the cone is at the cathode and that the strength is greatly affected by the angle that the dielectric makes with the applied field. Lucite, polystyrene, polyethylene, cast Nylon, and 7740 glass are shown to be relatively resistant to flashover in comparison with the ceramics and molded plastics. It is also observed that the surface strength in vacuum is a small fraction (approximately 1/10 or less) of the volume strength and consequently breakdown through the bulk seldom occurs. Data are given for several common insulating materials. View full abstract»

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    Features of shock wave formation in a wire induced surface flashover

    Lisitsyn, Igor V. ; Muraki, Taishi ; Akiyama, H.
    Applied Physics Letters

    Volume: 70 , Issue: 13
    DOI: 10.1063/1.118666
    Publication Year: 1997 , Page(s): 1676 - 1678
    Cited by:  Papers (5)

    AIP Journals & Magazines

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    Vacuum flashover characteristics of laminated polystyrene insulators

    Elizondo, J.M. ; Dragt, A. ; Krogh, M. ; Brooks, D. ; Smelser, R. ; Aragon, P. ; Happek, H. ; Torres, D. ; Ware, K.D. ; Prestwich, K.R.
    Pulsed Power Conference, 1999. Digest of Technical Papers. 12th IEEE International

    Volume: 1
    DOI: 10.1109/PPC.1999.825506
    Publication Year: 1999 , Page(s): 446 - 449 vol.1
    Cited by:  Papers (2)

    IEEE Conference Publications

    Laminated insulators consist of multiple layers of thin dielectric material stacked with metal films or thin metal layers. The formed stack withstands higher voltage than an equivalent, thick single-layer insulator. In the past materials like polyester, polycarbonate and polyamides have been used with values as high as 350 kV/cm for short pulse duration (50 to 100 nsec). Other materials, such as fuse silica, have also shown values as high as 175 kV/cm. These values have been accomplished with a straight dielectric wall stack of thin wafers. Such values make the lamination and stacking technique an excellent candidate for applications where bipolar pulses and low inductance restrict the use of the J.C. Martin standard 450 design. We report experimental results of similar stacked insulator configurations using cross-linked polystyrene thin wafers of 0.010-inch and 0.020-inch thick and SS 304 0.0005-inch thick. The voltage used for testing is produced by a triggered Marx generator capable of 400 kV output with a rise time of 25 nsec and a pulse length of about 1.5 /spl mu/sec. A voltage ring-up gain of about 20% is reported as the peak voltage and the RC line extension crossover as the averaged voltage. The results of testing different layer densities and different metal locations are described in this paper. We also describe the preparation and cleaning techniques that we have used, including plasma cleaning and pre-testing glow discharges. View full abstract»

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    Modeling of DC Flashover on Ice-Covered HV Insulators Based on Dynamic Electric Field Analysis

    Qing Yang ; Wenxia Sima ; Caixin Sun ; Lichun Shu ; Qin Hu
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 14 , Issue: 6
    DOI: 10.1109/TDEI.2007.4401224
    Publication Year: 2007 , Page(s): 1418 - 1426
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    In this paper, a model based on dynamic electric field analysis has been developed to predict the flashover voltage of the ice-covered HV insulators, under dc voltage. The potential and electric field calculation models before and after air gap breakdown are built respectively based on finite element method (FEM). The arc initiation process is determined based on the model before air gap breakdown. The critical applied voltage and leakage current to maintain an arc with certain length are obtained based on the electric field calculation model after air gap breakdown and the U-I characteristic of the arc. Moreover, the improved Hampton criterion has been employed to determine the critical flashover of the ice-covered insulator. The results obtained from the dynamic electric field analysis model have been compared with other mathematical and experimental results of other researchers and got a great agreement. View full abstract»

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    Contributing Factors to Window Flashover under Pulsed High Power Microwave Excitation at High Altitude

    Edmiston, G. ; Neuber, A. ; McQuage, L. ; Krile, J. ; Krompholz, H. ; Dickens, J.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 14 , Issue: 4
    DOI: 10.1109/TDEI.2007.4286507
    Publication Year: 2007 , Page(s): 783 - 789
    Cited by:  Papers (5)

    IEEE Journals & Magazines

    One of the major limiting factors for the transmission of high power microwave (HPM) radiation is the interface between dielectric-vacuum or even more severely between dielectric-air if HPM is to be radiated into the atmosphere. Surface flashover phenomena which occur at these transitions severely limit the power levels which can be transmitted. It is of major technological importance to predict surface flashover events for a given window geometry, material and power level. When considering an aircraft based high power microwave platform, the effects on flashover formation due to variances in the operational environment corresponding to altitudes from sea level to 50,000 feet (760 to 90 Torr; 1 Torr=133.3 Pa) are of primary interest. The test setup is carefully designed to study the influence of each atmospheric variable without the influence of high field enhancement or electron injecting metallic electrodes. Experimental data of flashover delay times across different materials, such as polycarbonate, Teflonreg, and high density polyethylene as a function of background pressure and gas type, air, N2, argon are discussed. An empirical relationship between flashover field amplitude and delay time is given. View full abstract»

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    Lightning protection of medium voltage overhead lines by modular long-flashover

    Podporkin, G.V. ; Pilshikov, V.E. ; Sivaev, A.D.
    Power Engineering Society Summer Meeting, 2002 IEEE

    Volume: 1
    DOI: 10.1109/PESS.2002.1043226
    Publication Year: 2002

    IEEE Conference Publications

    Summary form only given, as follows. A long flashover arrester (LFA) which comprises three flashover modules using the creeping discharge effect is described in this paper. In this design, the total arrester-stressing voltage is applied simultaneously to all the modules so that the voltage-time characteristics of the arrester are improved considerably assuring reliable protection of medium voltage (e.g. 10 kV) overhead power lines against both induced overvoltages and direct lightning strokes. A single LFA per support or pole is found to be sufficient to protect an overhead line against induced overvoltages. An LFA should be arranged in parallel with each insulator in order to protect a line against direct lightning strokes. View full abstract»

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    Preflashover and flashover phenomena of silicon–vacuum system under pulsed excitation

    Guan-Jun Zhang ; Yan, Z. ; Liu, Y.S. ; Yasuoka, K. ; Ishii, S.
    Applied Physics Letters

    Volume: 80 , Issue: 20
    DOI: 10.1063/1.1478785
    Publication Year: 2002 , Page(s): 3742 - 3744
    Cited by:  Papers (2)

    AIP Journals & Magazines

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    Surface Flashover Phenomenon Under 180-ns Quasi-Square Wave With Voltage of Several Hundred Kilovolts

    Cheng, Xin-bing ; Liu, Jin-Liang ; Zhang, Hong-bo ; Zhi-Qiang Hong ; Bao-Liang Qian
    Plasma Science, IEEE Transactions on

    Volume: 39 , Issue: 9
    DOI: 10.1109/TPS.2011.2161891
    Publication Year: 2011 , Page(s): 1868 - 1873

    IEEE Journals & Magazines

    Experiments on the surface flashover under 180-ns quasi-square waves with voltage of several hundred kilovolts are reported. In the experiments, employing a 280-kV 180-ns full-width at half-maximum (FWHM) voltage on the load, no flashover occurred. When the voltage was up to 350 kV, even 420 kV, surface flashover along the insulator occurred, and it started at the top part of the applied voltage pulse, so the FWHM of the output voltage of pulse generator was reduced to 150 ns, even 120 ns. Also, the experiment results show that surface flashover channel could be recovered quickly if a heteropolarity voltage was applied on the flashover channel. Finally, the characteristics of the surface flashover are present, including the flashover time, flashover current, and resistance. View full abstract»

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    Partial-arc and spark models of the flashover of lightly polluted insulators

    Waters, R.T. ; Haddad, A. ; Griffiths, H. ; Harid, N. ; Sarkar, P.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 17 , Issue: 2
    DOI: 10.1109/TDEI.2010.5448096
    Publication Year: 2010 , Page(s): 417 - 424
    Cited by:  Papers (1)

    IEEE Journals & Magazines

    The established model of the flashover of an insulator, whose surface is covered with a moist, conducting layer of pollution, envisages that it develops from the formation and bridging of a dry band by a partial-arc pre-discharge. This pre-discharge is assumed to possess arc characteristics, so that the electric field across the dry band will fall as the partial arc current increases. Observations of insulators which are only lightly polluted, however, show that pre-discharges are of low luminosity and rich in ultraviolet, and resemble the spark leader inception and extension sequence in air gaps. This is because the current limitation by low values of surface-layer conductance can inhibit the transition to an arc at the pre-discharge stage. An alternative model using simplified voltage-current equations is developed to represent these spark properties rather than an arc characteristic. The predictions of the partial-arc model and this new approach are both tested here, using published experimental data from light-pollution fog tests in the authors' laboratory. For this purpose, the partial-arc theory is further developed in order to reveal its implied prediction for the increase of pre-discharge length with applied voltage before flashover. A corresponding relationship is obtained for the increase of spark leader length using the new model. It is found that for light pollution, the dry-band spark model better represents the test data than the partial-arc model. Consequent predictions are made for the variation of flashover voltage with pollution severity in this regime, which may account for anomalous insulation failures. View full abstract»

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    Welch periodogram analysis of the leakage current on insulator model under wetted contaminated conditions for flashover prediction

    Douar, M.A. ; Mekhaldi, A. ; Bouzidi, M.C.
    MELECON 2010 - 2010 15th IEEE Mediterranean Electrotechnical Conference

    DOI: 10.1109/MELCON.2010.5476322
    Publication Year: 2010 , Page(s): 1636 - 1641
    Cited by:  Papers (2)

    IEEE Conference Publications

    This work is devoted to study the dielectric performances of a plane model wetted and contaminated by salt solutions having different conductivities. This insulator model simulates the 1512 L outdoor insulator which is greatly used by the Algerian Company of Gas and Electric Power (SONELGAZ). In this paper, we present signal processing results obtained through leakage current waveforms in order to predict the insulator flashover. These investigations were achieved after calculations operated on the leakage current energy by using the Welch frequency spectrum analysis. This frequency representation is performed on leakage current waveforms during the electric discharges activity appearing on the polluted plane surface. Reported results showed that the occurrence of electric discharges induced a progressive evaporation of the electrolytic solution and that this evaporation became stronger with the increase of pollution level. View full abstract»

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    Surface Flashover on Printed Circuit Boards in Vacuum under Electron Beam Irradiation

    Fujii, H. ; Kanja, I. ; Hasegawa, T. ; Osuga, H. ; Matsui, K.
    Discharges and Electrical Insulation in Vacuum, 2006. ISDEIV '06. International Symposium on

    Volume: 2
    DOI: 10.1109/DEIV.2006.357412
    Publication Year: 2006 , Page(s): 754 - 757

    IEEE Conference Publications

    This paper deals with the surface flashover characteristics of dielectric material during electron beam irradiation in vacuum in order to design the conductive patterns on printed circuit boards used inside a spacecraft adequately. The dielectric material and the electrodes printed on it were irradiated with electrons of the energy of 3-10keV. DC high voltage was applied between the two electrodes during electron irradiation. The voltage was increased step-wisely until the surface flashover occurred on the dielectric. We obtained the result that the surface flashover voltage increased with the insulation distance between the electrodes. However, electron irradiation caused the flashover voltage to lower. The flashover voltage characteristics were obtained as parameters of the electrode distance and the energy of the electron beam View full abstract»

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    Author's reply to "Flashover protection"

    Ciuciura, A.
    Radio and Electronic Engineer

    Volume: 38 , Issue: 5
    DOI: 10.1049/ree.1969.0112
    Publication Year: 1969 , Page(s): 292

    IET Journals & Magazines

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    Fault localization using IR lock-in thermography for flashover between the gate rail and the source metal clip

    Lau, C.K.
    Physical and Failure Analysis of Integrated Circuits (IPFA), 2012 19th IEEE International Symposium on the

    DOI: 10.1109/IPFA.2012.6306294
    Publication Year: 2012 , Page(s): 1 - 4

    IEEE Conference Publications

    This paper presents fault localization on MOSFET's gate-source continuity short failures using IR Lock-in Thermography which successfully detected a hot spot under the source metal clip without package decapsulation. Micro-sectioning analysis performed on the hot spot location revealed flashover between the source metal clip and the gate rail. View full abstract»

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    Flashover studies on HVDC bushings-development of DK model for non-condenser bushings

    Purushottam, Y. ; Balaji, N. ; Udayakumar, K. ; Dharmalingam, K.
    Properties and Applications of Dielectric Materials, 1994., Proceedings of the 4th International Conference on

    Volume: 2
    DOI: 10.1109/ICPADM.1994.414053
    Publication Year: 1994 , Page(s): 487 - 490 vol.2

    IEEE Conference Publications

    A new laboratory model, known as the didactically kindred (DK) model, for pollution studies on a noncondenser type transformer bushing is developed. The model is validated by carrying out laboratory tests on an actual bushing and on the model for initial potential distribution, and the results are reported. The patterns of dryband formation on both insulator and model are also observed and reported. Scintillation and flashover studies are also reported View full abstract»

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    Effects of Parameters on the Phase-to-Phase Flashover Characteristics of UHV Transmission Lines

    Miyake, K. ; Watanabe, Y. ; Ohsaki, E.
    Power Delivery, IEEE Transactions on

    Volume: 2 , Issue: 4
    DOI: 10.1109/TPWRD.1987.4308254
    Publication Year: 1987 , Page(s): 1285 - 1291
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    Phase-to-phase flashover characteristics needed for insulation design of UHV transmission lines, such as between 8-conductor to 8-conductors configuration and between the jumper line to the lower shield ring were investigated. The results include: (1) Effect of wave front duration of applied voltage. (2) Effect of positive-to-negative voltage ratio. (¿m) (3) Effect of time difference between wave peaks of positive and negative voltages. (4) Gap distance characteristics of flashover voltage. View full abstract»

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    Application of flashover characteristics of air gaps to insulation co-ordination

    Hughes, R.C. ; Roberts, W.J.
    Electrical Engineers, Proceedings of the Institution of

    Volume: 112 , Issue: 1
    DOI: 10.1049/piee.1965.0029
    Publication Year: 1965 , Page(s): 198 - 202
    Cited by:  Papers (6)

    IET Journals & Magazines

    Experimental data are presented on the flashover characteristics of rod-rod and rod-plane air gaps for unidirectional impulse voltages having different front durations. The data are used to examine a problem in the co-ordination of insulation, where it is required to protect a clearance approximating to a rod-plane configuration by a control gap provided by rod-rod electrodes. Comparisons are made with the flashover values for power-frequency voltages derived from published sources. View full abstract»

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    Inception and expansion process of surface flashover on solid dielectrics in vacuum

    Nakano, Y. ; Kojima, H. ; Hayakawa, N. ; Tsuchiya, K. ; Okubo, H.
    Electric Power Equipment - Switching Technology (ICEPE-ST), 2013 2nd International Conference on

    DOI: 10.1109/ICEPE-ST.2013.6804361
    Publication Year: 2013 , Page(s): 1 - 4

    IEEE Conference Publications

    Surface discharge on solid insulator in vacuum, which is one of the most significant phenomena under high electric field, prevents vacuum circuit breaker and vacuum interrupter from applying to higher voltage level. To clarify the mechanism of surface flashover, we investigated the transiently-formed charge characteristics on alumina dielectrics in the development process of surface flashover, by using electrostatic probes behind alumina dielectrics and measuring the light emission image of flashover. As a result, we found out that charge distribution on the alumina dielectrics in the inception of surface flashover depends on the electron emission sites on the cathode and influences the expansion process of surface flashover in vacuum. View full abstract»

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    Surface flashover threshold and switched fields of photoconductive semiconductor switches

    Loubriel, G.M. ; O'Malley, M.W. ; Zutavern, F.J. ; McKenzie, B.B. ; Conley, W.R.
    Electrical Insulation and Dielectric Phenomena, 1988. Annual Report., Conference on

    DOI: 10.1109/CEIDP.1988.26369
    Publication Year: 1988 , Page(s): 430 - 441
    Cited by:  Papers (6)

    IEEE Conference Publications

    It is shown that Si photoconductive semiconductor switches can be used to switch high voltages (up to 123 kV), high fields (up to 82 kV/cm) and high currents (2.8 kA). The ability of the samples to withstand this type of high-voltage, high-current switching depends on the way in which the current penetrates the semiconductor. The appropriate use of water or contacts greatly improves the switching capability. It is also shown that the wafers can support large currents (4.0 kA for GaAs and 2.8 kA for Si) and large linear current densities (3.2 kA/cm for GaAs and 1.4 kA/cm for Si). For GaAs this linear current density corresponds to about 1 MA/cm2 given a penetration depth of about 10-3 cm View full abstract»

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    Study on the icing flashover characteristics of porcelain double sheds suspension insulator string

    Yunpeng Liu ; Song Gao ; Daochun Huang ; Tao Yu ; Jie Lu ; Gang Meng ; Tao Xu ; Tao Yao
    Properties and Applications of Dielectric Materials, 2009. ICPADM 2009. IEEE 9th International Conference on the

    DOI: 10.1109/ICPADM.2009.5252329
    Publication Year: 2009 , Page(s): 721 - 724
    Cited by:  Papers (1)

    IEEE Conference Publications

    In the present paper, study on icing flashover characteristics were carried out in artificial climate chamber of State Grid Electric Power Research Institute (SGEPRI) with XWP2-160 porcelain double sheds suspension insulators. According to IEEE Task Force on insulator icing test methods the natural freezing rain condition was simulated and 3 to 7 units XWP2-160 insulators were icing energized at service voltage. Based on the tests results, the U50% increases with an increase in dry arcing distance linearly for XWP2-160 not more than 7 units. The effect on icing flashover performance of the factors such as ice thickness and applied water conductivity were investigated respectively. More over, ice states and discharge process of insulators icing energized were compared with the de-energized ones and discussed. For the air gaps can enhance the electrical strength of iced insulators, the U50% withstand voltage of insulators icing energized is higher than the de-energized ones. View full abstract»

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    Effect of different coning angles on flashover characteristics across machinable ceramic in vacuum

    Xue-Zeng Huang ; Jiang-Yang Zhan ; Nan Zheng ; Hai-Bao Mu ; Guan-Jun Zhang
    Electrical Insulating Materials (ISEIM), Proceedings of 2011 International Conference on

    Publication Year: 2011 , Page(s): 305 - 308

    IEEE Conference Publications

    Surface flashover in vacuum is a kind of complicated surface and interface phenomena, which seriously restricts the development of high voltage electro-vacuum devices. Introducing a kind of machinable ceramic with excellent machinable performance and good surface electrical capability into vacuum insulation system, and considering the commonly used truncated cone structure, machinable ceramic samples with different coning angles are machined. Their surface flashover voltage are investigated under pulsed voltage in vacuum, and the electric field distributions and surface charge density of different coning angles are numerically simulated. The experimental results indicate that, the flashover voltage of cone insulators is higher than that of cylindrical insulators, the flashover voltage of truncated cone samples with positive coning angle is much higher than that of with negative coning angles, and the flashover voltage with ~45° conical frustum is highest. It is considered that, the coning angle plays an important role on the electric field of cathode triple junction (CTJ) and surface charge distribution. When the coning angle is positive, the electric field of CTJ and surface charge distribution is smaller, and when the coning angle is negative, these values are bigger, so its higher CTJ electric field and surface charge result in a lower flashover voltage than that with positive angle, and also the short free path of electrons and decreased energy of electrons colliding with insulator surface lead to a higher flashover voltage than that of cylindrical insulators. View full abstract»

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    Impact of carbon particles on the impulse flashover behavior of different solid/liquid interfaces in a non-uniform field

    Krins, M. ; Borsi, H. ; Gockenbach, E.
    Electrical Insulating Materials, 1998. Proceedings of 1998 International Symposium on

    DOI: 10.1109/ISEIM.1998.741760
    Publication Year: 1998 , Page(s): 363 - 368
    Cited by:  Papers (7)

    IEEE Conference Publications

    This paper reports on experimental investigations dealing with the influence of carbon particles on the lightning impulse flashover behavior of the interface between insulating rods of different permittivities and surface structures and transformer oil in a non-uniform electrical field. The results reveal that for negative lightning impulse stress carbon particles in the oil act as defects due to their positive polarity and thus reduce the breakdown and flashover strength of all investigated materials distinctly. For positive impulse polarity no significant detrimental impact of the carbon particles on the electrical strength can be made out. Furthermore the contribution displays that in clean oil as well as in carbonized oil the probability of a surface tracking is for all investigated spacer materials markedly lower at positive impulse polarity than at negative lightning impulse stress View full abstract»

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    Aging evaluation of silicone rubber insulators using leakage current and flashover voltage analysis

    Ahmadi-Joneidi, I. ; Majzoobi, A. ; Shayegani-akmal, A.A. ; Mohseni, H. ; Jadidian, J.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 20 , Issue: 1
    DOI: 10.1109/TDEI.2013.6451360
    Publication Year: 2013 , Page(s): 212 - 220

    IEEE Journals & Magazines

    Ultraviolet (UV) radiation decreases the hydrophobicity of silicone rubber (SiR) insulators. Lack of hydrophobicity on the surface of such insulators lowers the flashover voltage and increases the Leakage Current (LC) of insulators in the moist environment. This paper presents the artificial UV radiation effects on three types of 20 kV SiR insulators in a chamber with nine UV-C lamps (50 W/m2) for up to 5000 hours. To simulate the moist environment, solid layer method is applied according to IEC 60507 that includes artificial pollution deposition on the insulator surface. Fast Fourier transform of the LC waveforms indicates that the third and the fifth harmonic components are quite sensitive to any incremental discharge on the insulator surface. This sensitivity makes the frequency spectrum of the LC a good criterion to distinguish three distinct SiR insulator situations under the electric stress: 1) no discharge, 2) dry band arcing/corona discharge and 3) continuous arc. Thermogravimetric analysis (TGA) and scanning electron microscope images depict that the polluted insulators include much larger degraded parts under electric stress after aging. Measurements also show that the flashover voltages and the hydrophobicity of aged insulators decrease as the UV exposure time increases for different levels of moisture and pollution. View full abstract»

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    Flashover arc motion and its effects on spacer-surface damage in gas-insulated systems

    Tekletsadik, K. ; Campbell, L.C.
    Generation, Transmission and Distribution, IEE Proceedings C

    Volume: 140 , Issue: 4
    Publication Year: 1993 , Page(s): 287 - 292

    IET Journals & Magazines

    Breakdown or flashover arcs in gas insulated systems (GIS) produce a magnetic force which influences the path of the arc and has a decisive effect on the spacer-surface damage experienced during flashovers. An experimental arrangement was developed to study breakdown/ flashover arc dynamics and their effect on spacer-surface damage in an 8 m experimental GIS. A mild-steel flange and aluminium disc piece were made to hold the test epoxy resin spacer and to have an access to take arc photographs in an open-to-air configuration at the open end of the GIS, with special spacer-electrode arrangements to study the arc lift off and push onto the surface during flashover on both sides of the spacer. The principle of arc dynamics is discussed, along with, experimental arrangements, results obtained from arc photographs and the effects of the arc path on spacer-surface damage View full abstract»

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    Insulator flashover in SF6 under impulse voltage conditions

    Al-Bawy, I. ; Farish, O.
    Science, Measurement and Technology, IEE Proceedings A

    Volume: 138 , Issue: 1
    Publication Year: 1991 , Page(s): 89 - 97
    Cited by:  Papers (4)

    IET Journals & Magazines

    The authors describe a study of the impulse-flashover characteristics of insulating spacers in an SF6-gas environment. Measurements have been made using 0.15/20 mu s and 0.15/1500 mu s waveforms for: plain cylindrical spacers; spacers with a defect at the insulator/gas/electrode triple junction; and spacers with metal inserts which shift the maximum field to the midgap region. The dependence of the surface charge accumulation on the rate of production of initiatory electrons is discussed. Metal inserts have been found to provide effective shielding of the triple junction, provided that the midgap field remains below the inception level. Unlike the case of the triple-junction defect where the region of enhanced field is highly localised, the inserts increase the field over a wide area so that the conditions for discharge propagation are satisfied at the inception level. This has been confirmed by comparison of the breakdown data with calculated values of discharge inception voltage. View full abstract»

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    Method of calculating shielding failure flashover times of transmission line in complex terrain area

    Qing-zhou Zhao ; Qing Yang ; Hao-yuan Zheng ; Wen-xia Sima ; Tao Yuan ; Jian-biao Li
    High Voltage Engineering and Application (ICHVE), 2012 International Conference on

    DOI: 10.1109/ICHVE.2012.6357120
    Publication Year: 2012 , Page(s): 330 - 333

    IEEE Conference Publications

    Calculating shielding failure flashover rate of transmission line with regulation method, EGM method and LPM method, the height of conductor and ground wire are often expressed by average height, the terrain feature are often expressed by ground obliquity. If the actual line parameters are beyond the scope of the effective calculation conditions, traditional methods can't reflect the influence of sag and line corridor's complex terrain area. In recent years, some scholars put forward to select multiple tangent planes of a line span, then calculated the shielding failure flashover rates of every tangent planes to reflect the line span's lightning protection performance, but it was complicated to get the ground obliquities of every tangent planes. A new approach for calculating shielding failure flashover times in complex terrain area was presented, which was based on the electro-geometric model (EGM), the new method considered of the line corridor's micro-topography and the relative position among the ground wire, the conductor wire and the ground, a line span was taken as the research object, got the shielding failure flashover times of the line span through calculating the conductor exposed surface's horizontally-projected area. A 500kV transmission line in complex terrain area was taken as an example, the calculation results shown that using this method can obtain a line span's lightning protection performance simple and exactly, and reflect the influence of line corridor's complex terrain area better, which also provide a reference for differentiation technology and strategy of lightning protection. View full abstract»

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    Flashover tests on air gap of ??800kV DC transmission line under composite DC and switching impulse voltage

    Yongli Liao ; Ruihai Li ; Chao Gao ; Guoli Wang ; Zhihong Liu
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 21 , Issue: 5
    DOI: 10.1109/TDEI.2014.004003
    Publication Year: 2014 , Page(s): 2095 - 2101

    IEEE Journals & Magazines

    This paper deals with the air gap insulation of ±800 kV DC transmission systems under composite DC and switching impulse voltage. The gaps studied were representative of ±800 kV DC transmission line, as rod-to-plane and conductor-to-tower gaps. The flashover voltages of the gaps at an altitude of 2100 m were determined for a pure switching impulse and composite voltages of DC and switching impulse. It is found that there are clear increase in the composite flashover voltage of both rod-to-plane and conductor-to-tower gaps, compared with those in the gap that only impulse voltage was applied. From the test results, the flashover voltage increases by 17-23%in the rod-to-plane gap and 5-10% in the conductor-to-tower gap, when the DC voltage of 800 kV is pre-stressed. The standard deviations have little obvious variation under the pre-stressed DC voltage and its average value is 4-4.5% in the tests. Additionally, a 1,000,000 fps high speed CCD camera is used to observe the breakdown process for investigation on the influence of pre-stressed DC voltage on the conductor. The leader inception and breakdown process properties were studied. These data and explanation are useful for ±800kV DC insulation design and testing. View full abstract»

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    The Influence of Gap Length on Flashover Under Nanosecond Pulsed Coaxial Electric Field

    Huang, W.L. ; He, L.L. ; Sun, G.S.
    Power and Energy Engineering Conference, 2009. APPEEC 2009. Asia-Pacific

    DOI: 10.1109/APPEEC.2009.4918885
    Publication Year: 2009 , Page(s): 1 - 4

    IEEE Conference Publications

    Under nanosecond pulsed coaxial electric field, surface flashover voltage over the interfaces between Nylon 1010 and transformer oil increases almost linearly with gap length, and the steeper rising edge of applied pulse, the higher flashover voltage. Surface flashover properties are closely related to the electric field at the triple junctions of solid-liquid-electrode and the field gradient along the interfaces. Although the increased difference between inner and outer electrode radii will enhance electric field strength at the triple junctions and nonuniformity degree of potential distribution along interfaces, it reduces simultaneously terribly the surface field strength of coaxial inner electrode, so that flashover voltage doesn't descend, but ascends almost linearly with gap length. The average flashover strength in coaxial electric field can be estimated by that in uniform electric field for large enough difference between inner and outer electrode radii, which is useful to practical engineering design for coaxial pulsed power apparatuses. View full abstract»

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    DC Flashover Voltage Characteristics of Contaminated Insulatirs

    Fujimura, T. ; Naito, K. ; Suzuki, Y.
    Electrical Insulation, IEEE Transactions on

    Volume: EI-16 , Issue: 3
    DOI: 10.1109/TEI.1981.298417
    Publication Year: 1981 , Page(s): 189 - 198
    Cited by:  Papers (10)

    IEEE Journals & Magazines

    An investigation was made of the influence of the dc power source on the withstand voltage ofntam-contaminated insulators. A thyristor-controlled power source was found stiff enough for the tests. DC contamination tests on various insulators were also carried out. The dc withstand voltage is generally lower than the ac one (rms). There seems to be a tendency that the rate of decrease in dc withstand voltage becomes larger as the contamination degree increases. The dc withstand voltage depends more strongly than the ac one on the insulator shape. The leakage distance per unit withstand voltage increases with the diameter of the insulator. The dc withstand voltage was also affected by the kind and the amount of insoluble material used, as is the case with ac. The withstand voltage decreases with an increase in the deposit density of insoluble material even at the same ESDD. The dc withstand voltage of the insulators ilators with noniform contam-contamination was not less than that based on ESDD assuming uniform contamination. Shown finally is then-conceptual design of insulator assemblies for the ±600 kV dc class. View full abstract»

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    Dynamic modeling of the temporal evolution of DC flashover discharge current with liquid electrolyte and ice pollution layer

    Slama, M.E.-A. ; Hadi, H. ; Flazi, S.
    Electrical Insulation Conference and Electrical Manufacturing Expo, 2007

    DOI: 10.1109/EEIC.2007.4562611
    Publication Year: 2007 , Page(s): 164 - 168

    IEEE Conference Publications

    A dynamic model for predicting dc flashover discharge current behavior of electrolyte and ice covered insulating surfaces is presented. The model takes into consideration insulating geometry, pre-contamination level, electrical field on the front of discharge and characteristics of pollution. Assuming discharge behavior as a time dependant resistance, it is possible to determine leakage currents characteristics and time of flashover using Hampton criteria for propagating of discharge and Rumeli criteria for estimating the displacement of the discharge assuming that the electrical breakdown stress on the front of discharge will be determined by the streamer criteria. The simulated results show that the model is in agreement with experimental results and is more appropriate for high resistance of pollution for electrolyte and ice layer. View full abstract»

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    Experimental study on surface flashover of a coaxial cable under nanosecond impulse voltage

    Min Han ; Shengju Lee ; Jinji Yang
    Properties and Applications of Dielectric Materials, 1988. Proceedings., Second International Conference on Properties and Applications of

    DOI: 10.1109/ICPADM.1988.38341
    Publication Year: 1988 , Page(s): 98 - 100 vol.1

    IEEE Conference Publications

    The flashover along the polythene surface of a coaxial cable has been studied under the condition of nanosecond impulse voltage. The average impulse flashover voltage for unit length E1 along the insulation length (D) of 5-15 cm was measured and found to be 6-3.5 kV/cm. The delay time of the flashover is in the range of 500-700 ns. The velocity of the propagation of discharge was measured and found to be 2±0.5×107 cm/s at D=12 cm. In order to compare with the DC values, the DC average flashover voltage for unit length was measured and found to be 7.8-5.8 kV/cm for D=5-15 cm. The authors measured the voltage-time curves of the flashover along the polythene surface and a pressurized spark gap View full abstract»

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    The effects of fluorination on the vacuum surface flashover voltage of polyimide

    Cheng, J. ; Su, J.C. ; Zhang, X.B. ; Liu, W.Y. ; Zeng, B. ; Wu, X.L. ; Fang, J.P. ; Sun, X. ; Wang, L.M. ; Zhao, L.
    Electrical Insulation and Dielectric Phenomena (CEIDP), 2013 IEEE Conference on

    DOI: 10.1109/CEIDP.2013.6747456
    Publication Year: 2013 , Page(s): 464 - 467

    IEEE Conference Publications

    The effects of fluorination on the vacuum surface flashover voltage (Uf) of polyimide (PI) are researched. The experimental results show that as the degree of fluorination increases, the Uf of PI firstly increases and then decreases, the highest Uf in the experiments is increased by up to 21% compared with untreated PI sample. The results of Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectric spectroscopy (XPS) show that fluoride treatments may cause the structural change of PI. A mechanism based on the abstraction of the atoms of H, O and N is proposed. During the process of fluorination, the formation of the C-F bonds can improve the surface flashover voltage, whereas as the degree of fluorination increases, the destruction of the C-N bonds would degrade the surface flashover performance. The two processes play the role at the same time. Therefore, there is an optimal degree for the fluorination. View full abstract»

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    DC Flashover Voltage Characeteristics and Their Calculation Method for Oil-Immersed Insulation Systems in HVDC Transformers

    Kurita, A. ; Takahasi, E. ; Ozawa, J. ; Watanabe, M. ; Okuyana, K.
    Power Delivery, IEEE Transactions on

    Volume: 1 , Issue: 3
    DOI: 10.1109/TPWRD.1986.4307991
    Publication Year: 1986 , Page(s): 184 - 190
    Cited by:  Papers (15)

    IEEE Journals & Magazines

    The effects of the laminated paper layer direction on the conductivity and the dc breakdown strength in oil-impregnated paper were experimentally clarified. It was confirmed that not only oil and paper discharges through the laminated paper layers, but also paper discharges along them triggered total flashover in oil and oil-impregnated paper composite insulation. Analyses verified the usefulness of the dc flashover voltage calculation method, based on a non-linear directional field calculations and the lowest flashover voltage estimations between paper discharges along the laminated paper layers and oil and paper discharges through them. View full abstract»

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    Improvement of surface flashover characteristics about 45° insulator configuration in vacuum by a new organic insulation structure

    Qifeng Huang ; Shengtao Li ; Tuo Zhang ; Fengyan Ni ; Jianying Li
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 18 , Issue: 6
    DOI: 10.1109/TDEI.2011.6118652
    Publication Year: 2011 , Page(s): 2115 - 2122

    IEEE Journals & Magazines

    In the present paper, a new three-layered 45° insulation structure is proposed and investigated to further improve the surface flashover performance of the 45° vacuum- insulator configuration. This structure was prepared by inserting organic composite between the electrode and insulator. With a numerical simulation method, the electric field distributions in this structure were analyzed. The result shows that by adjusting the permittivity of the inserted layer between the electrode and insulator, the electric field at the cathode and anode triple junction can be suppressed significantly in order to prevent the appearance of the surface flashover in vacuum. On the basis of these theoretical analyses, we conducted a series of vacuum flashover experiments about the new three-layered insulation structure of polyethylene composite-polyethylene-polyethylene composite. In our experimental result, it is indicated that when the permittivity of the inserted layer change in certain range, the surface flashover performance in vacuum of the 45° vacuum-insulator configuration can be improved, e.g. the highest first impulse flashover voltage reaches to 81 kV and increases by 32% compared with the polyethylene standard samples. View full abstract»

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    Vacuum surface flashover and high pressure gas streamers

    Elizondo, J.M. ; Krogh, M.L. ; Smith, D. ; Stoltz, D. ; Wright, S.N. ; Sampayan, S.E. ; Caporaso, G.J. ; Vitello, P. ; Tishchenko, N.
    Pulsed Power Conference, 1997. Digest of Technical Papers. 1997 11th IEEE International

    Volume: 2
    DOI: 10.1109/PPC.1997.674531
    Publication Year: 1997 , Page(s): 1027 - 1032 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    Pre-breakdown current traces obtained during high pressure gas breakdown and vacuum surface flashover show similar signatures. The initial pre-breakdown current spike, a flat constant current phase, and the breakdown phase with voltage collapse and current surge differ mostly in magnitude. Given these similarities, a model, consisting of the initial current spike corresponding to a fast precursor streamer (ionization wave led by a photoionizing front), the flat current stage as the heating or glow phase, and the terminal avalanche and gap closure, is applied to vacuum surface flashover. A simple analytical approximation based on the resistivity changes induced in the vacuum and dielectric surface is presented. The approximation yields an excellent fit to pre-breakdown time delay versus applied field for previously published experimental data. A detailed kinetics model that includes surface and gas contributions is being developed based on the initial approximation. View full abstract»

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    Flashover characteristics of discrete water droplets on the surface of super-hydrophobic silicone rubber

    Jin, H. ; Jin, P. ; Niu, R. ; Li, Y. ; He, B. ; Gao, N. ; Zhang, H.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 21 , Issue: 4
    DOI: 10.1109/TDEI.2014.004281
    Publication Year: 2014 , Page(s): 1718 - 1725

    IEEE Journals & Magazines

    Super-hydrophobic silicone rubber (SIR) was fabricated by hot-pressing template method, and its surface water droplet contact angle reached 153.5¿¿ and sliding angle 8¿¿. The observation of microstructure showed that there were plenty micrometer-scale papillas and nanometer-scale particles on its surface, the mechanism of superhydrophobicity caused by this micro-nano hierarchical structure was discussed. In order to study the influence of super-hydrophobicity on the electric field distribution, twodimensional simulation was carried out in software platform ANSYS. The influence of contact angle, volume and location was discussed. The simulation results indicated that super-hydrophobic surface had a better effect of electric field shielding. The flashover experiments (for both single and double droplets on different SIR surface) were carried out and showed that the flashover voltage of super-hydrophobic SIR with droplets on its surface was higher than that of ordinary SIR, which confirmed the simulation. View full abstract»

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    What polymers and fiberglass reinforced plastics (FRP) may add to classical primary insulation of distribution system construction for withstanding lightning critical flashover voltages (CFO)

    Shwehdi, M.H. ; Quasem, M.A. ; Elhadri, M.
    Electrical Insulation, 1994., Conference Record of the 1994 IEEE International Symposium on

    DOI: 10.1109/ELINSL.1994.401433
    Publication Year: 1994 , Page(s): 205 - 208

    IEEE Conference Publications

    Insulation composites used on present-day distribution lines frequently consist of two or more types of materials such as wood, porcelain, polymers and fiberglass reinforced plastics (FRP) connected in series. A study included the laboratory determination of the critical flashover voltage (CFO) of 17 single component, 90 combinations of 2 component and 80 combinations of 3 component, and the acquired data were used to develop methods of predicting CFO levels of various multiple series electrical insulations. This paper illustrates the results and analyses of the classical primary insulation (porcelain), and of the modern-day insulation of polymers or FRP. It also presents results of whether these newly emerged FRP and polymers may add or supplement insulation strength to the two and three dielectrics combination. The paper also presents advantages and guidelines for the use of polymers and FRP to either replace or complement porcelain. This may help optimize the choice of dielectrics on distribution lines View full abstract»

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    A Comparison of European and American Wet Flashover Test Methods

    Kingsbury, Bruce E.
    Power Apparatus and Systems, Part III. Transactions of the American Institute of Electrical Engineers

    Volume: 79 , Issue: 3
    DOI: 10.1109/AIEEPAS.1960.4500748
    Publication Year: 1960 , Page(s): 271 - 275
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    First Page of the Article
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    Application of Dynamic Model to Flashover of Ice-covered Insulators

    Fofana, I. ; Farzaneh, M.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 14 , Issue: 6
    DOI: 10.1109/TDEI.2007.4401223
    Publication Year: 2007 , Page(s): 1410 - 1417
    Cited by:  Papers (3)

    IEEE Journals & Magazines

    The purpose of this paper is to study the effect of insulator dimensions as well as applied water conductivity on flashover voltage under icing conditions, using a dynamic arc model. The electrical performance of several insulators with various diameters and dry arcing distances were evaluated using this model. Moreover, in order to assess the influence of meteorological variables, different applied water conductivities were considered for the laboratory experiments. The model was found to be in good agreement with the experimental results. The results obtained indicate that flashover prediction is possible under ac voltage, using the proposed model. This contribution is also intended to provide a fresh perspective by contributing an innovative approach to this domain of research. View full abstract»

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    The Effect of Humidity on the Dry Flashover Potential of Pin-Type Insulators

    Littleton, J.T. ; Shaver, W.W.
    American Institute of Electrical Engineers, Transactions of the

    Volume: 47 , Issue: 2
    DOI: 10.1109/T-AIEE.1928.5055002
    Publication Year: 1928 , Page(s): 438 - 441
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    This paper shows that humidity affects considerably the flashover voltages of porcelain and Pyrex insulators. The flashover potential rises as the humidity is increased. The tests were made on pin-type insulators and on rods. The results show that this rising characteristic is a surface effect which varies with the absolute water content of the surrounding atmosphere. View full abstract»

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    Rigorous analysis of back-flashover outages caused by direct lightning strokes to overhead power lines

    Chowdhuri, P. ; Li, S. ; Yan, P.
    Generation, Transmission and Distribution, IEE Proceedings-

    Volume: 149 , Issue: 1
    DOI: 10.1049/ip-gtd:20020011
    Publication Year: 2002 , Page(s): 58 - 65
    Cited by:  Papers (3)

    IET Journals & Magazines

    In estimating the lightning-caused outage rate, insulator voltage is at present computed by neglecting the induction effects of the electromagnetic fields of the lightning channel and the magnetic fields of the tower travelling current waves. An analytical method is proposed to take these effects into account. The induction effect of the lightning channel significantly increases the insulator voltage, whereas that of the tower travelling current waves decreases the insulator voltage. However, the overall effect is to increase the insulator-string voltage, giving an outage rate higher than that by currently used methods. The proposed method of estimating the outage rate by backflash should provide a better tool for the design of the lightning performance of overhead power lines. View full abstract»

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    DC flashover of a dielectric surface in atmospheric conditions

    Krile, J.T. ; Neuber, A. ; Dickens, J.C. ; Krompholz, Hermann G.
    Plasma Science, IEEE Transactions on

    Volume: 32 , Issue: 5 , Part: 1
    DOI: 10.1109/TPS.2004.835483
    Publication Year: 2004 , Page(s): 1828 - 1834
    Cited by:  Papers (6)

    IEEE Journals & Magazines

    Surface flashover is a major consideration in a wide variety of high-voltage applications, and yet has not been studied in great detail for atmospheric conditions, with modern diagnostic tools. Environmental conditions to be considered include pressure, humidity, and gas present in the volume surrounding the dielectric. In order to gain knowledge into the underlying process involved in dielectric surface flashover, a setup has been created to produce and closely monitor the flashover event. Within the setup parameters such as geometry, material, and temporal characteristics of the applied voltage can be altered. Current, voltage, luminosity, and optical emission spectra are measured with nanosecond to subnanosecond resolution. Spatially and temporally resolved light emission data is also gathered along the arc channel. Our fast imaging data show a distinct trend for the spark in air to closely follow the surface even if an electrical field with a strong normal component is present. This tendency is lacking in the presence of gases such as nitrogen, where the spark follows more closely the electric field lines and develops away from the surface. Further, the breakdown voltage in all measured gases decreases with increasing humidity, in some cases as much as 50% with an increase from 10% relative humidity to 90% relative humidity. View full abstract»

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    The repetitive breakdown and flashover properties of solid dielectric materials under DC and pulsed conditions

    McPhee, A.J. ; MacGregor, S.J. ; Tidmarsh, J.R.
    Power Modulator Symposium, 1996., Twenty-Second International

    DOI: 10.1109/MODSYM.1996.564472
    Publication Year: 1996 , Page(s): 145 - 148
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper reports on the results of a test programme to investigate the material limits of solid dielectric insulation at potentials in excess of 100 kV. This comparative study of various materials was not an attempt to optimise the material breakdown voltage but to make a direct sample comparison under identical, representative pulsed power conditions. The electrical breakdown characteristics of various materials were studied using kV pulses which are representative of those generated in a typical high voltage transmission line system. The investigation was carried out for both DC and pulsed voltages, the latter operating at repetition rates of up to 100 pps. The broad aims of this test programme were to compare the flashover and breakdown performance of different materials in air and in oil, to compare the voltage characteristics of insulating tubes and insulating films for different materials and to investigate the effect of repetitive operation and pulse charging upon solid insulation. The breakdown voltage of PTFE, acrylic, Pyrex glass and polycarbonate tubes was measured and compared using a standard test arrangement. This enabled direct comparison to be made between the different materials. The flashover potential of these materials was also measured as a function of gap spacing in silicone oil and air. Breakdown tests were also carried out for tubes made from many layers of polypropylene and polyester films. These were wound under vacuum and impregnated with silicone oil to minimise trapped air effects. Electrostatic modelling of the test set up was also carried out View full abstract»

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    Investigation of the flashover of a FRP hot stick while in use for live line work at 500 kV

    McDermid, W. ; Bromley, J.C. ; Dodds, D.J. ; Swatek, D.R.
    Power Delivery, IEEE Transactions on

    Volume: 14 , Issue: 3
    DOI: 10.1109/61.772387
    Publication Year: 1999 , Page(s): 1158 - 1166
    Cited by:  Papers (4)

    IEEE Journals & Magazines

    In October 1997 Manitoba Hydro experienced the flashover of a FRP hot stick during live line work at 500 kV AC. The paper describes the live line work which was being done, the weather and the condition of the hot stick. A series of tests were made to investigate factors which may have contributed to the flashover. The adequacy of available tests for FRP hot sticks is discussed. The corrective measures which have been taken prior to resuming work of this type are described View full abstract»

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    Insulator surface flashover with UV and plasma background and external magnetic field

    Hegeler, F. ; Krompholz, H. ; Hatfield, L.L. ; Kristiansen, M.
    Electrical Insulation and Dielectric Phenomena, 1995. Annual Report., Conference on

    DOI: 10.1109/CEIDP.1995.483603
    Publication Year: 1995 , Page(s): 171 - 174

    IEEE Conference Publications

    Surface flashover often sets the limit on the maximum voltage of a system in vacuum. UV irradiation and/or plasma will further decrease the flashover potential. This experiment investigates the UV and plasma induced dielectric surface flashover, emphasizes the early phase of breakdown, and uses external magnetic fields to increase the surface flashover potential. In our experimental apparatus, a dc voltage up to 60 kV or a voltage pulse (up to 100 kV with 200 ns duration) is applied to the test gap. The geometry of all interconnecting lines and of the discharge chamber is coaxial and the impedances are closely matched. The current, voltage, and soft X-rays are recorded. The plasma is generated by an electron cyclotron resonance plasma source and the UV radiation originates from a UV enhanced dc Xenon arc lamp. External magnetic fields influence the current in the pre-flashover phase. With a magnetic flux density of only 30 mT, the flashover potential of a UV induced breakdown increases by up to a factor of 4. With a plasma background, the duration of an applied voltage pulse can be increased by a factor of 2 without causing flashover View full abstract»

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    A new multichannel gas spark switch base on surface flashover technology

    Tie, Weihao ; Zhang, Qiaogen ; Liu, Shanhong ; Liu, Xuandong
    Plasma Science (ICOPS), 2012 Abstracts IEEE International Conference on

    DOI: 10.1109/PLASMA.2012.6383495
    Publication Year: 2012 , Page(s): 1P-167

    IEEE Conference Publications

    Summary form only given. As one of the critical elements of fast linear transformer driver(FLTD), gas switch influences the output characteristics, stability and reliability of FLTD. In this paper, a new multichannel gas spark closing switch has been designed for LTD. The trigger electrode is mainly constituted of eight pin electrodes, each pin electrode is surrounded by cylindrical insulation sleeve to produce surface flashover, which plays UV-preillumination feature. In order to observe the discharge process of the new gas switch, the polished organic glass insulation chambers instead of the nylon ones have been used. A discharge circuit called LTD brick has been established to test the performance of gas spark switch. The self-breakdown voltage with different gas pressure has been studied to obtain the working coefficient of switch. The triggered breakdown delay time and jitter under different charge voltage, gas pressure and working coefficient have been studied. Finally, the results of experiments show that surface flashover can promote the stable production of multichannel discharge effectively and reduce delay time and jitter. View full abstract»

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    The influence of magnetic fields on dielectric surface flashover

    Korzekwa, R. ; Lehr, M. ; Krompholz, H. ; Kristansen, M.
    Power Modulator Symposium, 1990., IEEE Conference Record of the 1990 Nineteenth

    DOI: 10.1109/MODSYM.1990.201008
    Publication Year: 1990 , Page(s): 277 - 280

    IEEE Conference Publications

    The effect of magnetic fields on dielectric surface flashover was investigated using two experimental setups, one with DC magnetic fields and the other with pulsed magnetic fields produced by currents of up to 175 kA. The observed insulation effects depend on the dielectric material, ambient gas pressure, surface roughness, and the presence of background plasma. It is sufficient to place the magnetic field in the vicinity of the cathode region only. For practical applications, small low-cost NdFe permanent magnets can be used, even for plasma background conditions with an electron density of 104 cm-3. The flashover voltage retains the characteristic dependence proportional to the square root of the gap distance with and without the applied magnetic field for DC magnetic field experiments View full abstract»

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    Influence of air-gap characteristics on the icing flashover performance for the plate model of composite insulators

    Hao Jiang ; Guang Yang ; Zhidong Jia ; Yu Deng ; Zhicheng Guan ; Tianzheng Wang ; Kangning Wang
    Electrical Insulation and Dielectric Phenomena (CEIDP), 2013 IEEE Conference on

    DOI: 10.1109/CEIDP.2013.6748187
    Publication Year: 2013 , Page(s): 478 - 481

    IEEE Conference Publications

    The air-gaps will appear in the ice-layer during icing and ice-melting process of composite insulators. The icing flashover process and flashover voltage are obviously affected by the air-gaps. In order to research the influence of the air-gaps on the icing flashover performance of composite insulators, the icing flashover tests were carried out by using the plate model of insulators. The influence of different characteristics of the air-gaps on the flashover performance of the model, such as the length, position, number and angle of model was researched, and the flashover process, variation of the leakage current and flashover voltage under different kinds of air-gaps were also compared. The results show that, the development path of the arc changes with the different characteristics of the air-gaps. The flashover voltage decreases at first and then increases with the increasing of the length and model angel of the air-gaps. The flashover voltage increases when the distance between the air-gap and the electrode becomes larger, and the increasing of the air-gap number can also increase the flashover voltage with the constant whole length of the air-gaps. View full abstract»

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    D-C Machine Flashover and Bus Short-Circuit Protection

    Montgomery, T.B. ; Sellers, J.F.
    American Institute of Electrical Engineers, Transactions of the

    Volume: 60 , Issue: 12
    DOI: 10.1109/T-AIEE.1941.5058248
    Publication Year: 1941 , Page(s): 1168 - 1173
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    The transient induced voltage across the interpole and compensating windings of d-c motors or generators on short circuit or flashover provide a quick and convenient means of actuating circuit breaker or other protective devices. Such means have made possible quicker tripping times than are obtained with the conventional series overload or reverse current protection. View full abstract»

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    Real-time detection of outgassing and plasma buildup during the early phase of dielectric surface flashover

    Masten, G. ; Muller, T. ; Hegeler, F. ; Krompholz, H. ; Hatfield, L.L.
    Pulsed Power Conference, 1993. Digest of Technical Papers., Ninth IEEE International

    Volume: 1
    DOI: 10.1109/PPC.1993.513322
    Publication Year: 1993 , Page(s): 241 - 244
    Cited by:  Papers (2)

    IEEE Conference Publications

    Employing a newly developed refractive index sensor, we gather additional information about the processes involved in dielectric surface flashover. The sensor detects gradients in the refractive index above the dielectric surface, time-correlated with other signals of interest, by measuring the deflection of a focused laser beam. It utilizes a 10 mW HeNe laser beam incident on a bi-cell solid state photodetector to provide a signal with angular sensitivity on the order of 0.18 mV/μrad, and temporal resolution of 6 ns. This new diagnostic component is combined with current, voltage, luminosity, and x-ray sensors that have risetimes ranging from 0.4 to 3 ns. To the knowledge of the authors, this is the first application of this diagnostic principle to the problem of dielectric surface flashover. Preliminary measurements with the refractive index diagnostic demonstrate the existence of a time-changing refractive index above the dielectric surface accompanying the exponential rise of the flashover current. These measurements can be interpreted to indicate the formation of a plasma channel a few tens of microns above the dielectric surface, which expands with a velocity on the order of 106 cm/s . A fraction of these measurements display an indication of neutral gas desorption, within the threshold of detection, prior to flashover. View full abstract»

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    Inhibiting surface flashover with magnetic fields

    Korzekwa, R. ; Lehr, M. ; Krompholz, H. ; Kristiansen, M.
    Energy Conversion Engineering Conference, 1989. IECEC-89., Proceedings of the 24th Intersociety

    DOI: 10.1109/IECEC.1989.74500
    Publication Year: 1989 , Page(s): 441 - 445 vol.1

    IEEE Conference Publications

    The influence of magnetic fields on dielectric surface flashover is investigated for simple geometries and a variety of parameters (different dielectric materials, presence of ambient gas and plasma). Models based on the saturated secondary electron avalanche predict that magnetic insulation starts at the lowest amplitudes of the magnetic field if the avalanche electrons are lifted off the surface due to the E×B drift, which is in agreement with the experimental results. For practical applications, especially for low Earth orbit conditions, small-volume, low-weight permanent magnets with field amplitudes of 0.1 T are sufficient to increase the flashover voltage by more than 50% View full abstract»

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    Critical condition of DC flashover on a circular sector model

    Flazi, S. ; Boukhennoufa, N. ; Ouis, A.
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 13 , Issue: 6
    DOI: 10.1109/TDEI.2006.258205
    Publication Year: 2006 , Page(s): 1335 - 1341

    IEEE Journals & Magazines

    In order to find the electrical size which determined the critical condition of flashover, the authors have examined the propagation of the discharge on surface under DC voltage in a new laboratory model which has a continuous and radial current distribution. This model is a vat having a circular sector form of variable angles, radiuses and depths filled by an electrolyte. The obtained results on this model show that for a given resistivity of electrolyte: if the current distribution in the horizontal plane is uniform according to the sector angle, the applied critical voltage and the critical current per unit of angle (1deg) are constant for all sectors of various angles, if the current distribution in the vertical plane is uniform according to the depth, the critical flashover voltage and the critical current per unit of the electrolyte depth (1 mm) are constant for all the depths. These results lead to the critical conditions of flashover to be determined by the current per unit of angle and per unit of electrolyte depth (A/deg/mm) View full abstract»

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    Insulator surface conduction state and surface flashover voltage

    Vlastos, A.E. ; Hulten, J.
    Electrical Insulation and Dielectric Phenomena, 1995. Annual Report., Conference on

    DOI: 10.1109/CEIDP.1995.483763
    Publication Year: 1995 , Page(s): 463 - 466

    IEEE Conference Publications

    The withstand of aged and or contaminated insulators has to be tested in a humid environment under controlled conditions. However, during the humidification the conduction state of the aged and/or contaminated insulators shows a temporal variation. The time at which the maximum conductance is reached depends on the insulator material, design, humidification rate and the severity of contamination. The results of this work show that the maximum conductance of naturally aged and/or contaminated composite polymeric insulators under moderate humidification conditions is reached after a time in the order of one hour. However, contaminated ceramic barrel insulators conductance is reached after a much longer time which is of the order of a couple of hours. The presented results show that when the test voltage is applied at the time when the conductance of the insulator is maximum the electric withstand of the insulator is in its minimum View full abstract»

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    Study on Pollution Flashover Performance of Short Samples of Composite Insulators Intended for ±800 kV UHV DC

    Xingliang Jiang ; Jihe Yuan ; Zhijin Zhang ; Jianlin Hu ; Lichun Shu
    Dielectrics and Electrical Insulation, IEEE Transactions on

    Volume: 14 , Issue: 5
    DOI: 10.1109/TDEI.2007.4339479
    Publication Year: 2007 , Page(s): 1192 - 1200
    Cited by:  Papers (13)

    IEEE Journals & Magazines

    Based on the artificial pollution tests, the effects of pollution and high altitude on the flashover performance of short samples of five kinds of UHV/EHV dc composite long rod insulators are analyzed. The exponent characterizing the influence of salt deposit density on the flashover voltage is related with the profile and the material of the insulator shed. The values of the samples' exponents vary between 0.24 and 0.30, which are smaller than those of porcelain or glass cap-and-pin insulators, namely, the influence of the pollution on the composite long rod insulators is less, relatively. Thus, the composite insulators have certain advantages in severe pollution regions. The best ratio of the leakage distance to the arcing distance is about 3.35. The exponent characterizing the influence of air pressure on the flashover voltage is related with the profile and the material of the insulator shed and the pollution severity, the values of the samples' exponents vary between 0.6 and 0.8, which are larger than those of porcelain or glass cap-and-pin insulators. Therefore, the dc composite insulator used in high altitude regions should have enough arcing distance. Based on the test results, if insulator sample Type E is selected for the plusmn800 kV UHV dc transmission lines, the basic arcing distance should be no less than 8.16 m and the basic leakage distance no less than 30.2 m. View full abstract»

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    A study of short-time ac flashover voltage of contaminated insulators and a consideration of its application to transmission line insulation design

    Itabashi, T. ; Osada, K. ; Seta, Taisuke ; Naito, K.
    Power Apparatus and Systems, IEEE Transactions on

    Volume: 95 , Issue: 5 , Part: 1
    DOI: 10.1109/T-PAS.1976.32271
    Publication Year: 1976 , Page(s): 1723 - 1731
    Cited by:  Papers (2)

    IEEE Journals & Magazines

    Insulator contamination is the decisive factor in making insulation design of most transmission lines in Japan. This paper describes the performance of contaminated insulators against a short-time ac overvoltage in the order of several cycles, taking into consideration comparatively higher overvoltage due to the one-phase-to-ground fault of recent long-distance bulk power transmission lines with series capacitors. It has been made clear by this study that, in the case of a fault clearance within 0.07 sec, e.g., the flashover voltage increases by about 15% more than in a continuous energization. This implies that the insulation of series-capacitor-compensated lines can be met by the conventional insulation design levels. View full abstract»

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    Investigation of elbow and insulated bushing cap flashovers during unloaded switching

    Walling, R. ; Komassa, D. ; Lazar, J. ; Shattuck, G.B.
    Power Engineering Society Summer Meeting, 2000. IEEE

    Volume: 1
    DOI: 10.1109/PESS.2000.867633
    Publication Year: 2000 , Page(s): 480 - 485 vol. 1

    IEEE Conference Publications

    Extensive testing has been performed in an effort to identify the phenomena responsible for widespread field reports of unexplained flashovers while switching 25 and 35 kV elbows to drop unloaded and lightly loaded cables. A large number of elbow and cap pulling operations were performed under a wide range of conditions. In addition, mechanical tests were performed to characterize relationships between lubrication, displacement, and partial vacuum developed between elbows and bushings during pulling. While the low flashover rate achieved in the laboratory testing does not support statistically valid correlation of flashovers to circuit, mechanical, and environmental factors, the test results provide significant information. In particular, the results imply that commonly accepted explanations for the flashovers may be incomplete, and that there are complexities to the phenomena which are yet to be fully understood View full abstract»

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    Numerical electromagnetic field analysis of archorn voltages during a back-flashover on a 500-kV twin-circuit line

    Mozumi, T. ; Baba, Y. ; Ishii, M. ; Nagaoka, N. ; Ametani, A.
    Power Delivery, IEEE Transactions on

    Volume: 18 , Issue: 1
    DOI: 10.1109/TPWRD.2002.803828
    Publication Year: 2003 , Page(s): 207 - 213
    Cited by:  Papers (9)

    IEEE Journals & Magazines

    Archorn voltages of a simulated 500-kV twin-circuit line, in the case of one-phase back-flashover due to lightning to a tower top, are analyzed by the thin-wire time-domain analysis (TWTDA) code. Prior to this analysis, a recently proposed flashover model is incorporated into TWTDA. It becomes clear that the archorn voltages of the other two phases show a quite similar time-varying characteristic after one-phase back-flashover. An EMTP simulation is also carried out. The archorn voltages computed by the electromagnetic transients program (EMTP) agree well with those computed by TWTDA before the back-flashover on one phase. On the other hand, during about 1 μs after the one-phase back-flashover, the archorn voltages of the other two phases computed by EMTP deviate much from those computed by TWTDA. Particularly in the case of the middle- or the lower-phase back-flashover, the deviation is noticeable. The reason for this discrepancy is discussed. View full abstract»

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    High‐speed photography of surface flashover of solid insulators under impulse voltages in vacuum

    Cross, J.D. ; Srivastava, K.D.
    Applied Physics Letters

    Volume: 21 , Issue: 11
    DOI: 10.1063/1.1654253
    Publication Year: 1972 , Page(s): 549 - 551
    Cited by:  Papers (11)

    AIP Journals & Magazines

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