• Title, Summary, Keyword: Lightning impulse

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Characteristic Changes of ZnO Arrester Blocks by Multiple-lightning Impuse Currents (다중 뇌충격전류에 의한 산화아연형 피뢰기 소자의 특성 변화)

  • Gil, Gyeong-Seok;Han, Ju-Seop
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.12
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    • pp.685-690
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    • 2000
  • Multiple-lightning impulse currents are a general feature of the lightning ground f=flash. It is therefore necessary for lightning arresters used in power systems to be estimated by applying not only a single-lightning impulse current but also a multiple-lightning impulse currents. This paper presents the effects of multiple-lightning impulse currents on deterioration of ZnO arrester blocks. The multiple-lightning impulse generator which can produce quadruple 8/20$[\mus]$ 5[kA] with separation time of 30~120[ms] is designed and fabricated. The total energy applied to the arrester block at each impulse is about 1,200[J]. In experiment, various parameters such as leakage current component, reference voltage, and temperature are measured with the number of applied impulse current. Also, micro-structure changes of the ZnO blocks after applying the single and the multiple-lightning impulse currents of 200 times are compared. The experimental results indicate that the types of arrester blocks are more vulnerable to deterioration or damage by multiple-lightning impulse currents.

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Hydrodynamic Modeling for Discharge Analysis in a Dielectric Medium with the Finite Element Method under Lightning Impulse

  • Lee, Ho-Young;Lee, Se-Hee
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.397-401
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    • 2011
  • The response of lightning impulse voltage was explored in dielectric liquids employing hydrodynamic modeling with three charge carriers using the finite element method. To understand the physical behavior of discharge phenomena in dielectric liquids, the response of step voltage has been extensively studied recently using numerical techniques. That of lightning impulse voltage, however, has rarely been investigated in technical literature. Therefore, in this paper, we tested impulse response with a tip-sphere electrode which is explained in IEC standard #60897 in detail. Electric field-dependent molecular ionization is a common term for the breakdown process, so two ionization factors were tested and compared for selecting a suitable coefficient with the lightning impulse voltage. To stabilize our numerical setup, the artificial diffusion technique was adopted, and finer mesh segmentation was generated along with the axial axis. We found that the velocity from the numerical result agrees with that from the experimental result on lightning impulse breakdown testing in the literature.

Degradation Properties of ZnO Surge Arresters Due to Lightning Impulse Currents (뇌임펄스전류에 의한 ZnO 피뢰기의 열화특성)

  • Lee, Su-Bong;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.4
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    • pp.79-85
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    • 2009
  • This paper describes the degradation properties of ZnO surge arresters impressed by lightning impulse currents. To investigate the deterioration behaviors of ZnO surge arresters due to lightning surges, the 8/20[${\mu}s$], 2.5[kA] standard lightning impulse currents were injected to the ZnO surge arrester under test. The power frequency AC and DC leakage currents flowing through the ZnO surge arresters with and without the injection of lightning impulse currents were measured. As a result, the leakage currents are increased and the asymmetry of the AC leakage current is pronounced as the number of injection of the impulse current increases. The ZnO grain of the surge arrester without the injection of lightning surges are uniform but the ZnO grain of the ZnO surge arrester with the injection of lightning impulse currents are deformed. Also, it was found that the decrease of the $Bi_2O_3$ due to the lightning impulse current leads to the lack of grain boundary layer and the current concentrated by the lack of grain boundary layer play an important role to degrade nonlinear property of ZnO surge arrester blocks.

Change of Electrical Characteristics of ZnO Arrester Blocks by Lightning Impulse Current (뇌충격전류에 의한 산화아연형 피뢰기 소자의 전기적 특성변화)

  • Gil, Gyeong-Seok;Han, Ju-Seop;Park, Yeong-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.7
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    • pp.550-555
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    • 1999
  • This paper deals with the effect of lightning impulse current on electrical characteristics of ZnO blocks used in distribution lightning arrester. The electrical characteristics of ZnO blocks are degraded by overtime impulse current, and the degraded ZnO block is brought to a thermal runaway and finally destroyed. It is therefore important to estimate the change of electrical characteristics of ZnO blocks. In this study, an impulse current generator which can produce 8/20$[\mus]$, 3[㎄] and 4/10$[\mus]$, 5[㎄] waveform is designed and fabricated to simulate the lightning impulse current of power systems. Total energy applied to the ZnO blocks at each time is 739[J] in 8/20$[\mus]$, and 523[J] in 4/10$[\mus]$, impulse current, respectively. From the experimental results, the 3rd harmonic of the leakage current increases continuously with the number of applied impulse current, but no significant changes in residual voltage and in reference voltage are observed until the ZnO block is destroyed. Also, it is confirmed that the main factor on degradation of ZnO blocks is rather the total energy applied to ZnO blocks than the peak value of the impulse current.

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Performance Evaluations of the Lightning Impulse Voltage Measuring System by Intercomparative Test - in case of full lightning impulse voltage - (뇌충격 측정시스템의 비교시험에 의한 성능평가 - 전파 뇌충격전압 인가시 -)

  • Kim, Ik-Soo;Kim, Young-Bae;Lee, Hyeong-Ho
    • Proceedings of the KIEE Conference
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    • pp.1368-1370
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    • 1995
  • Lightning impulse voltage is essential to evaluate the insulation performance of electric power apparatus. Recently international standard(IEC-60) on high voltage measurement techniques are being revised. In the draft of this standard, a new calibration method is introduced and the accuracy of most industrial measuring systems is maintained by means of comparison test against the reference measuring systems. Intercomparison tests of dividers for lightning impulse measurement were carried out by KERI. The shielded resisitive divider with 700kV rating developed by KERI were done comparison test with PTB divider with 300kV rating which have the similar charateristics as that were circulated among the laboratories. This paper reports on the comparison test results with full lightning impulse voltages from 126kV to 240kV. It is demonstrated that KERI are capable of realizing the idea in the revision of the IEC standand, that is, to establish traceability.

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A Study on the step response characteristics in shielded resistor divider for full lightning impulse voltage (전파 뇌충격전압 측정용 쉴드저항분압기의 직각파 특성에 관한 연구)

  • 김익수;이형호;조정수;박정후
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.2
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    • pp.283-288
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    • 1996
  • This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation.

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Changes of Electrical Characteristic of ZnO Varistors by a Lightning Impulse Current (뇌충격전류에 의한 산화아연형 바리스터의 전기적 특성변화)

  • 이종혁;손원진;김명진;길경석
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.581-584
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    • 2000
  • This paper describes the effect of lightning impulse current on ZnO varistors(390 V, 6.5 kA) used in low-voltage AC mains as a protective device against transient overvoltages. A lightning impulse current standardized in IEC 61000-4-5 is applied to the varistors, and the energy applied to the varistor at each time is about 12 J. In the experiment, various Parameters such as leakage current, reference voltage are measured with the number of applied impulse current. Also, micro-structure changes of the varistors after applying the lightning impulse current of 200 times are compared. The electrical characteristics of the varistors are degraded by overtime impulse current, showing increase in leakage current and decrease in reference voltage.

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Series-Gap Characteristics of Transmission Line Arrester with Switching and Lightning Impulse Flashover Test (개폐서지 및 뇌충격 섬락시험에 따른 송전 피뢰기의 직렬공극 특성)

  • Cho, Han-Goo;Yoo, Dae-Hoon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.484-485
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    • 2007
  • This paper describes the series-gap characteristics of transmission line arrester with switching and lightning impulse flashover test. The transmission line arrester exhibited external gap because it is must not flashover with switching impulse on the other hand it is must flashover with lightning impulse. In accordance, minimum and maximum length of series-gap was determinated with these tests. As gap length is increased flashover voltage was increased in the range of 315.4 kV~496.3 kV and negative polarity exhibited a high voltage. As a result, It was thought tat the series-gap length of transmission line arrester exhibited in the range of 580 mm~1100 mm.

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Intercomparison of Ll measurement system of KERI (뇌충격전압 측정시스템의 국제 비교시험-II)

  • Kim, Ik-Soo;Jeong, Joo-Young;Choi, Jae-Gu;Kim, Ick-Kewn;Shin, Young-June
    • Proceedings of the KIEE Conference
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    • pp.1555-1557
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    • 2001
  • To compare the lightning impulse measurement capabilities of high voltage laboratory, a lightning impulse voltage measuring system from HUT is circulated around the world. This paper presents test results after second round of this worldwide exercise. KERI's impulse voltage measuring system compared with the circulating reference measuring system from HUT at voltage levels of 80, 160, 240, 320 and 400 kV. Three impulse shapes were used, i.e. full smooth lightning impulse with both short (0.84 $\sim$ 0.95 ${\mu}s$) and long front (1.45 $\sim$ 1.56 ${\mu}s$), and chopped impulse with time to chopped impuse. Impulse peak value ($U_p$) and time parameters ($T_1$, $T_2$ and $T_c$) according to IEC 60060-1 were compared.

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Characteristics of Lightning Impulse Current of Zno Block for Transmission Line Arrester with External Gap (송전선로에 사용되는 갭형 피뢰기 소자의 뇌임펄스 전류특성)

  • Cho, Han-Goo;Yoo, Dae-Hoon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.61-62
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    • 2009
  • This paper describes the characteristics of lightning impulse current of ZnO block for transmission line arrester with external gap. The ageing parameters of lightning arresters ate impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by impulse current. Total energy applied to the ZnO arrester each time is $4/10{\mu}s$, 30kA and $2/20{\mu}s$, 10kA impulse current. Before and After the test, the residual voltage variation of varistors passed was below 5%. According to the test, it is thought that the ZnO arrester shows good stability with impulse current test.

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