• 전기학회논문지
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• 제66권2호
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• pp.363-369
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• 2017

This paper presents the experimental results related to soil ionization and electrical breakdown in a concentric hemispherical electrode system under lightning impulse voltages. Dynamic voltage-current and impedance-time characteristics of soil ionization were measured and analyzed. Also the electrical breakdowns of the soil gap were investigated. The time-lag to the peak current corresponds to the soil ionization propagation. The time of ionization propagation in wet sand is found to decrease with increasing the impulse currents. A drastic decrease in ground resistance was observed during the impulse current spreading in sand. The electrical breakdown appears at the wave tail of impulse voltage and results in a wide scatter in V-t curves. The voltage-current curves have a fan-like shape attributed to ionization processes which result in increasing current and decreasing voltage.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.275-279
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• 2005

This paper presents leakage current characteristics as a function of injected number and magnitude of impulse current, when$8/20{\mu}s$ lightning impulse current is injected to ZnO varistor. The life of ZnO varistor against $8/20{\mu}s$ lightning impulse current was evaluated. The injected number of the test current to breakdown was inversely proportional to the amplitude of impulse current.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권5호
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• pp.257-262
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• 2006

To evaluate the change in protective levels of zinc oxide (ZnO) varistors after the surge absorption, this paper investigated the effects of the number of injection and amplitude of lightning surges on the life of ZnO varistors for low voltages. Leakage currents flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages were measured. The surge simulator system ECAT that can generate $8/20{\mu}s$ impulse currents with a peak short-circuit of 5 $[kA_p]$ was used. The ZnO varistor leakage current increases with exposure to impulse current, and the number of injection of $8/20{\mu}s$ impulse currents to breakdown was inversely proportional to the amplitude of the test current. Behaviors of ZnO varistor leakage currents were strongly dependent on the number of injection and amplitude of $8/20{\mu}s$ impulse currents. ZnO varistors degrade gradually when subjected to impulse current, and the resistive leakage current flowing through ZnO varistors subjected to the $8/20{\mu}s$ impulse currents under 60 Hz AC voltages was significantly increased after a certain number of injection that is dependent on the amplitude of the test impulse current. As a result, the life of ZnO varistors mainly depends on the amplitude and occurrence frequency of lightning surges.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.199-201
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• 2007

This paper presents the installation of measuring system for the transient behaviors of grounding system impedances using portable impulse current generator. The measuring system is controller, with controller, power supply, impulse current generator and data aquisition system. In the evaluation of the impulse response in a ground electrode, the step response is calculated based on the ratio of the voltage and current observed.

• 조명전기설비학회논문지
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• 제26권5호
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• pp.79-84
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• 2012

As the huge economical loss and function paralysis of information technology-based systems can be caused by the misoperation of residual current devices(RCDs) due to surge voltages and currents, RCDs shall not operate by surge currents. In this paper, in order to evaluate the reliability of residual current operated circuit-breakers with integral overcurrent protection for household and similar uses((RCBOs) stressed by surges, the unintended trip characteristics of RCBOs under surge currents were experimentally investigated using the combination wave generator. Seven different types of single-phase RCBOs being present on the domestic market were investigated according to KS C IEC 61009-1 standard. As a result, all kinds of specimens were satisfied the requirements for 0.5 [${\mu}s$]/100[kHz] ring wave impulse currents. Most of specimens stressed by the 8/20[${\mu}s$] impulse current tripped at least one or more, and some of them were broken down during consecutive tests. It was found that only one type of specimens meets the L-N mode immunity to the combination wave of 1.2/50[${\mu}s$] impulse voltage and 8/20[${\mu}s$] impulse current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1418_1419
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• 2009

This paper presents the transient impedance when high current impulse up to 5 kA is applied to a scaled grounding grid in test field. For a realistic analysis of transient impedance on the high current impulse in the ground systems, grounding electrode installed outdoors and impulse current generator was used. The results were discussed based on its voltage and current trace, impulse impedance and V-I curve.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2132-2134
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• 2000

Since surge arresters are recommended to protect the electric power system from the lighting surge, the impulse current is generally used to verify this requirement at the test labotaries. Recently, the international standard(IEC 60060-2) related to the impulse current techniques revised requiring a traceability of measuring system for impulse current measurements. In this paper, a shunt for impulse current is developed satisfing the revised IEC standard and the possibility of application has been investigated using step response.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권12호
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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.

• 한국정보통신학회논문지
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• 제4권4호
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• pp.793-801
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• 2000

본 논문에서는 저전압 교류회로에서 과도이상전압에 대한 보호소자로 사용되는 산화아연형 바리스터의 뇌충격전류에 대한 영향에 대하여 기술하였다. 산화아연형 바리스터는 뇌충격전류에 의해 열화가 진행되며, 열화된 바리스터는 정상 운전전압에서도 열폭주에 도달하여 파괴되므로, 바리스터의 전기적 특성변화를 평가 하는 것은 대단히 중요하다. 바리스터를 가속열화시키기 위하여 국제규격 IEC 61000-4-5에 규정된 뇌충격전류를 적용하였으며, 1회의방전에 바리스터에는 약 12(J)의 에너지가 인가된다. 뇌충격전류의 인가에 따른 바리스터의 누설전류, 정격전압 등을 측정하였으며, 또한 바리스터에 뇌충격전류를 200회 인가 후 초기상태의 미세구조와 비교하였다. 실험결과로부터 바리스터는 뇌충격전류의 인가에 따라 누설전류는 증가하고 정격전압은 감소하는 경향을 나타내면서 전기적 성능이 저하됨을 확인하였다.

• 조명전기설비학회논문지
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• 제19권1호
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• pp.94-100
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• 2005

본 논문은 전류유입위치에 따른 봉상접지전극의 과도 및 실효임펄스임피던스의 특성에 관한 것으로 뇌격전류를 인가하여 실규모 접지봉에 대한 시간영역에서의 성능을 평가하였다. 임펄스전류가 가해진 봉상접지전극의 과도 접지임피던스는 접지저항보다 높게 나타났으며, 접지전극의 길이가 길어짐에 따라 접지저항과 실효임펄스접지임피던스는 감소되었다. 또한 실효임펄스접지임피던스는 짧은 시간범위에서는 급격하게 증가하였다. 접지저항의 저감은 접지시스템의 임펄스임피던스 특성의 개선에 결정적인 역할을 한다. 임펄스전류를 접지봉의 하단에 인가하였을 때 접지봉 전위의 파두부에 고주파의 진동 파형이 포함되고 실효임펄스임피던스는 다른 경우보다 높게 나타났다.