• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.297-300
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• 2008

This paper presents the behaviors of transient and conventional grounding impedances of a deep-driven ground rods associated with the injection point of lightning impulse currents. The transient impedance of deep-driven ground rods under lightning impulse currents were higher than the static ground resistance. The transient grounding impedances strongly depend on the injection point and size of grounding electrodes and the rising time of impulse current. Reduction of ground system inductance is an important factor to lightning surge protection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2274-2276
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• 2005

Cyclic aging for 14days is performed to remove the large amount of the volatiles found in freshly manufactured cable. In this paper, we examined lightning impulse characteristics of power cable before and after cyclic aging for 14days. As the result, the breakdown voltage after aging was lower than that before aging, but the breakdown voltage after aging was higher than that before aging in TR CNCV-W $60mm^2$ power cable.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.144-150
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• 2008

In this paper, the safety for passengers of composite car-body against lightning strikes was analyzed by the application of an impulse generator which can produce impulse current up to 50 [kA] with 8/20 [us] waveform. Potential difference on inside surface of the car-body was measured as a safety parameter for the passengers against lightning strikes. The potential difference between 20 [cm] distant was 175 [V] at 37.67 [kA], and it corresponded to 875 [V] between 1 [m] distant. The amount of charge flowing a passenger at 100 [kA] impulse current can be estimated to 0.31 [mA s]. This is much less than the limit amount of charge for human body, 30 [mA s] which is presented by Koeppen and Osypka.

• 한국화재소방학회논문지
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• 제25권1호
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• pp.50-56
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• 2011

최근 지구온난화에 의한 영향으로 낙뢰의 발생빈도가 증가하는 추세이고, 낙뢰에 수반되는 뇌격전류의 강도 또한 강해지고 있는 추세이다. 2008년 기준 국내의 낙뢰 발생 빈도는 56만여 건 정도가 발생하였으며, 낙뢰로 인한 인명피해 사고 및 건축구조물의 피해는 나날이 증가하고 있다. 특히, 낙뢰로 인한 전기화재는 낙뢰 발생에 따른 대지전위 상승으로 접지선과 전원선간 절연파괴 과정에서 발생되며, 현장조사 결과, 낙뢰 발생 지역에 인접한 지역에서 동시다발적으로 전기적 피해가 발생하였다. 낙뢰에 대한 피해를 방지하기 위해서는 낙뢰 보호 장치의 설치 및 등전위 접지 시행 등의 방법이 요구된다. 또한 낙뢰로 인한 화재현장 조사에 있어서는 기상청에서 제공되는 낙뢰 발생 기록 및 화재현장과 인접한 지역에서 동시다발적인 전기적 특이점 형성 여부에 대한 검토가 필요하다.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.207-214
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• 2004

This paper presents the characteristics of transient and effective impulse impedances for deeply driven grounding electrodes used in soil with high resistivity or in downtown areas. The laboratory test associated with the time domain performance of grounding piles subjected to a lightning stroke current has been carried out using an actual-sized model grounding system. The ground impedances of the deeply driven ground rods and grounding pile under impulse currents showed inductive characteristics, and the effective impulse ground impedance owing to the inductive component is higher than the power frequency ground impedance. Both power frequency ground impedance and effective impulse ground impedance decrease upon increasing the length of the model grounding electrodes. Furthermore, the effective impulse ground impedances of the deeply driven grounding electrodes are significantly amplified in impulse currents with a rapid rise time. The reduction of the power frequency ground impedance is decisive to improve the impulse impedance characteristics of grounding systems.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1877-1879
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• 2000

This paper deals with the change of the micro-structure of ZnO associated with lightning surge current and ageing test. In this work, a surge current generator which can produce 8/20 [${\mu}s$], 6 [kA] impulse current is designed and fabricated to simulate the lightning impulse current. The residual voltage and leakage current flowing to ZnO blocks are observed. Also a compensation circuit was used in resistive current measurement. The micro-structures of ZnO arrester block were significantly changed by lightning surge current and accelerated temperature ageing test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.229-229
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• 2009

This Impulse Voltage and Current Test System is designed for performing of impulse voltage tests with Lightning impulse voltage 1.2/50(LI) up to 1520kV peak value and switching impulse voltages 250/2500(SI) up to 1120kV peak valu acc. to IEC 60060-1, and furthermore for impulse current test, e.g. testing of arrester sections($U_{res}$=95kV)with current impulses 4/10 and 8/20 up to 70kA peak value.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.131-136
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• 2011

This paper aims to examine the possibility of using an environmentally friendly $N_2$ as an alternative gas to $SF_6$. For this purpose, we have investigated breakdown characteristics of $N_2$ under impulse voltages in a quasi-uniform electric field gap. The 1.2/50[${\mu}s$] lightning impulse voltage, switching impulse voltages and oscillatory impulse voltages were applied at the test gap. The electric field utilization factor ranges from 0.5 to 0.8. The experimental data of $SF_6$ and $N_2$ acquired in the same experimental condition are presented in parallel for comparison. As a result, the breakdown voltages in $SF_6$ and $N_2$ are linearly increased with the gas pressure, also the breakdown voltages in $N_2$ are increased with increasing the gap distance and electric field utilization factor. The positive breakdown voltages are higher than the negative breakdown voltages. The nagative basic lightning impulse withstand level of 150[kV] in $N_2$ of about 0.5[MPa] is nearly equal to that in $SF_6$ of 0.15[MPa]. It is seen from the results obtained in this work that $N_2$ can be used as an eco-friendly alternative gas to $SF_6$ in distribution power equipment.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.446-454
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• 2016

In this paper, we present experimental results of the soil discharge characteristics as a function of moisture content when a 1.2/50-㎲ lightning impulse voltage is applied. For this study, laboratory experiments were carried out based on factors affecting the transient behavior in soils. The electrical breakdown voltages in soils were measured for a 0-6% range of moisture content for sand and a 0 - 4% range of moisture content for gravel. A test cell with semi-spherical electrodes buried face-to-face in the middle of a cylindrical container was used. The distance separating the electrodes is 100 mm. As a result, the time-lag to breakdown in soils decreases as the amplitude of applied voltage increases. The time-lag to initiation of ionization streamer is decreased, with an increase in the moisture content. However, the formative time-lag is rarely changed. The behavior of soil discharges depend not only on the type of soil and its moisture content but also on the amplitude of the impulse voltage. When the test voltage is applied repeatedly, electrical breakdown occurs along different discrete paths, leading radially away from the injected electrode. i.e., the fact that the ionization streamers propagate in different paths from shot to shot was observed.