• Title, Summary, Keyword: Electric breakdown

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A study on conduction current and D.C. breakdown characteristics in dielectric liquids (절연유의 도전전류와 직류절연파괴특성에 관한 연구)

  • 서국철
    • 전기의세계
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    • v.30 no.4
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    • pp.231-236
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    • 1981
  • It has been known that D.C. breakdown Voltage is lower than A.C. breakdown Voltage in insulatingoil, but there are still many unvivid points at electric conduction in breakdown or under of high electric field. This study measured the electric current-electric field characteristics (I-E characteristics) and the breakdown Voltage under of D.C. electric field of insulating oil using the system of electrodes that are near the Uniform electric field with a result. I can study, electric conduction in area of high electric field depends upon the Schottky effect. The liquidity of breakdown electric field takes place by the local concentration of electric field. The longer gap is and the more electric current is the more breakdown Voltage decreased. There are not almost the change of electric current-electric field characteristics by materials of electrode.

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Electrical Breakdown Properties of Oil-paper Insulation under Pulsating Voltage Influenced by Temperature

  • Bao, Lianwei;Li, Jian;Zhang, Jing;Li, Xudong
    • Journal of Electrical Engineering and Technology
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    • v.11 no.6
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    • pp.1735-1743
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    • 2016
  • Insulation of valve-side windings in converter transformer withstands pulsating voltages, which will produce more serious insulation problems. In this paper, the electric breakdown experiments of oil-paper insulation specimens were executed at pulsating voltages and different temperatures. Experiment and analysis results showed that the breakdown voltage decreased with increasing temperature under pulsating voltage. The influence of temperature proves to be more significant once the temperature exceeds a limitation threshold. A fitting formula between breakdown voltage and the temperature was reported. Finally, in order to clearly understand the breakdown properties under pulsating voltage, the electric field distribution and space charge behavior under pulsating voltage at different temperature were discussed.

Analysis of Fire Accident on DC Electric Traction Vehicles Caused by Breakdown in the Line Breaker (회로 차단기 절연파괴로 인한 직류 전기철도 화재 사고사례 분석)

  • Park, Nam-Kyu;Song, Jae-Yong;Goh, Jae-Mo;Kim, Jin-Pyo;Nam, Jung-Woo
    • Journal of the Korean Society of Safety
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    • v.32 no.6
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    • pp.16-21
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    • 2017
  • Fire or electrical problem while DC electric traction vehicle operation caused by various reasons can lead to not only suspension of the operation, but also severe aftermath such as massive casualty. In this paper, fire analysis on DC electric traction vehicle caused by electrical breakdown on line breaker, which is in connection with the power supply, is presented. When the electric arc, the by-product of frequent line breaker operation, is not fully diminished, it leads to electrical breakdown and fire. Especially, electrical breakdown can be easily induced by the open-and-close operation of inner contractor inside line breaker, eventually followed by ground fault and generation of transient current. Electric arc is consequent on the ground fault and acts as possible ignition source, leading to fire. Also, during the repetitive operation of the line breaker, the contactor is separated each other and some copper powder is generated, and the copper powder provided breakdown path, resulting in fire.

Effect on Metal Guard Ring in Breakdown Characteristics of SiC Schottky Barrier Diode (금속 가드 링이 SiC 쇼트키 다이오드의 항복전압에 미치는 영향)

  • Kim, Seong-Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.10
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    • pp.877-882
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    • 2005
  • In order to fabricate a high breakdown SiC-SBD (Schottky barrier diode), we investigate an effect on metal guard ring (MGR) in breakdown characteristics of the SiC-SBD. The breakdown characteristics of MGR-type SiC-SBD is significantly dependent on both the guard ring metal and the alloying time of guard ring metal. The breakdown characteristics of MGR-type SiC-SBDs are essentially improved as the alloying time of guard ring metal is increased. The SiC-SBD without MGR shows less than 200 V breakdown voltage, while the SiC-SBD with Al MGR shows approximately 700 V breakdown voltage. The improvement in breakdown characteristics is attributed to the field edge termination effect by the MGR, which is similar to an implanted guard ring-type SiC-SBD. There are two breakdown origins in the MGR-type SiC-SBD. One is due to a crystal defects, such as micropipes and stacking faults, in the Epi-layers and the SiC substrate, and occurs at a lower electric field. The other is due to the destruction of guard ring metal, which occurs at a higher electric field. The demolition of guard ring metal is due to the electric field concentration at an edge of Schottky contact metal.

A Study on the Electric Field Analyses and Improvement of Insulation Characteristics on the Ribbed Spaced for GIS (GIS 립 스페이서에 대한 전계해석 및 절연특성 개선에 관한 연구)

  • 류성식;최영찬;곽희로
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.2
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    • pp.59-64
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    • 2002
  • This paper analyzed the effect of ribs on the breakdown characteristics when a metallic particle attaches on the various spot of GIS spacer, using electric field analysis. Also, it was compared with the experimental result of breakdown voltage characteristics for the spacer with a metallic particle on its various spot and with the shape, the length, and the thickness of the ribs varying. The results of electric field analysis show that the electric field concentration of the rib is more weakened than other parts and therefore it restrains the proceeding of streamer, which occurs at the breakdown. And it is verified through experiments that the breakdown voltage of the spacer with rib is higher than that of the spacer without rib. The breakdown characteristics depend on the shape, the length, and the thickness of the rib as well. Also, it is confirmed by the electric field analysis and the experimental results that the electric breakdown characteristics could be improved by rounding the rib edge.

Copper Particle Effect on the Breakdown Strength of Insulating Oil at Combined AC and DC Voltage

  • Wang, You-Yuan;Li, Yuan-Long;Wei, Chao;Zhang, Jing;Li, Xi
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.865-873
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    • 2017
  • Converter transformer is the key equipment of high voltage direct current transmission system. The solid suspending particles originating from the process of installation and operation of converter transformer have significant influence on the insulation performance of transformer oil, especially in presence of DC component in applied voltage. Under high electric field, the particles easily lead to partial discharge and breakdown of insulating oil. This paper investigated copper particle effect on the breakdown voltage of transformer oil at combined AC and DC voltage. A simulation model with single copper particle was established to interpret the particle effect on the breakdown strength of insulating oil. The experimental and simulation results showed that the particles distort the electric field. The breakdown voltage of insulating oil contaminated with copper particle decreases with the increase of particle number, and the breakdown voltage and the logarithm of particle number approximately satisfy the linear relationship. With the increase of the DC component in applied voltage, the breakdown voltage of contaminated insulating oil decreases. The simulation results show that the particle collides with the electrode more frequently with more DC component contained in the applied voltage, which will trigger more discharge and decrease the breakdown voltage of insulating oil.

The Electrical Characteristics of Varistor. (바리스터의 전기적 특성)

  • Hong, Kyung-Jin;Jang, Dong-Hwan;Cho, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.52-56
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    • 2001
  • The Breakdown electric field of ZnO semiconductor devices in voltage-current characteristics was increased by increasing of additive materials. The specimen that has not additive materials was not formed spinel structure. The critical voltage that has not spinel structure was 235[V]. When the additive materials has 0.5 and 2[mol%], the Breakdown electric field was 840 and 758[V] in each additive materials. The Breakdown electric field of varistors as a factor of voltage and current was increased by addition of oxide antimony. The varistors that has oxide antimony was linearly increased in low electric field.

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A study on the Electric Breakdown Mechanisms using Self-helfing Method of Thin Film (Self-healing 방법을 이용한 박막의 절연파괴 현상 연구)

  • Yun, J.R.;Kwon, C.R.;Se, K.W.;Park, I.H.;Lee, H.Y.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.11-13
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    • 1992
  • The dielectric reliability of the Thin $SiO_2$ films of wet oxidation on n-type Si substrates has been studied by using self-healing method of breakdown and according to injection time high frequence C-V tests. These experiments have been performed to investigate the dielectric breakdown mechanism of a thin film in which positive charge generation during high-field Fowler-Nordheim tunneling are considered. In addition, The weak spots and robust areas are distinguished so that the localized dielectric breakdown could be described.

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The Breakdown Phenomena of N2 gas by RF Electric Field (라디오 주파수전계에 의한 질소가스의 브레이크 다운 현상)

  • 황기웅;노영수
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.35 no.5
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    • pp.199-204
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    • 1986
  • The breakdown phenomena of N2 gas by 13.56MHz electric field are very different from those under steady field. In this paper we analyzed the breakdown phenomena by using electron distribution function and diffusion equation. The second-order differential equation derived from the Boltzmann equation is solved for the electron distribution function. The ionization rate and diffusion coefficient are calculated using kinetic theory formulas. The breakdown condition is that the number of electrons produced by ionization equal the number diffusing to the walls of the discharge chamber. Theses theoretical breakdown electric fields are calculated by the computer and compared with the experimental values.

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Electric Field Analysis with Imaginary Streamer Process and Insulation Characteristics on the Ribbed Spacer for GIS (GIS 립 스페이서의 가상스트리머 진전에 따른 전계해석 및 절연특성)

  • Ryu, Sung-Sic;Choi, Young-Chan;Lee, Chang-Ryong;Kwak, Hee-Ro
    • Proceedings of the KIEE Conference
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    • pp.1649-1651
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    • 2001
  • The effect of ribbed spacers having metallic particle attached to the post-type spacer on dielectric breakdown phenomena has been investigated using electric field analysis for imaginary streamer process and a breakdown experiment. It was described that the electric field analysis and the dielectric breakdown test were performed on the case that the particle was attached to the various position of the ribbed spacer having various shapes. As a result, the breakdown voltage of the spacer with two ribs was highest, and it was varied by the length and the thickness of the rib. Especially, in case of the rib with round edge, the breakdown voltage was higher than that with rectangular edge, which complied with the result through the field analysis.

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