• 조명전기설비학회논문지
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• 제29권4호
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• pp.95-101
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• 2015

This paper presents experimental results about characteristics of soil discharge as a function of moisture content when the $1.2/50{\mu}s$ lightning impulse voltage is applied. The laboratory experiments, for this study, were carried out based on factors affecting the transient behavior in soils. The electrical breakdown in soils was measured over a 0-6% range of moisture content for sands and a 0-4% range of moisture content for gravels. Needle-plane electrode systems was used As a result, the conduction current prior to ionization growth in dry soil is a little, but it in wet soil is increased with the applied voltage because the wet soil particles act as conductors. The soil impedance curves show an abrupt reduction just after breakdown. The general tendency measured in different soils is that the higher the water content, the lower the breakdown voltage and the shorter the time-lag to breakdown.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1656-1658
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• 1998

This paper deals with a measurement system of a distance between lightning strokes and observatory station and spectrum analysis of electric fields radiated from lightning discharges. The distance measurement system, which consists of a loop type magnetic field sensor, a microphone and one chip microprocessor, is connected to a personal computer through RS232 port to acquire and process the data. This system is to use a difference of propagation velocity between an electromagnetic wave and a sonic wave produced by lightning discharge. Also, an electric field waveform and a frequency spectrum were investigated by an electric field measurement system with a hemisphere antenna and a spectrum analyzer with a biconical antenna and a log-periodic antenna, respectively. The results would be used as a basic reference to protect the power systems and electric circuits from lightning overvoltages.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.581-585
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• 2004

The wave shapes of electromagnetic pulses radiated from lightning discharges are significantly changeable one of the topics concerning on EMI/EMC of modern electronic systems is the efficient and economic protection of electronic circuits against transient voltages caused by not only by cloud-to-ground lightning but also by intracloud lightning discharges. In this work, in order to obtain the detailed information about lightning electromagenetic pulses, the electromagnetic pulses radiated from intracloud lightning discharge processes were measured and analyzed statistically.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2164-2166
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• 1999

This paper is describes the measured electric field waveform radiated by lightning discharge. We have performed measurement and analysis of the electric fields associated with stepped leaders. Electric field measurement system was composed of hemisphere electric field sensor, measurement system of a distance from lightning strokes, automatical recording system, A/D board, personal computer etc. A/D board have high sampling time, high speed data processing, 8bit of resolution. Also, measured characteristics of stepped leaders radiated by were analyzed.

• 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.

• 조명전기설비학회논문지
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• 제28권10호
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• pp.63-68
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• 2014

This paper deals with a methodology that applies the time-varying magnetic fields produced by the cloud discharges to find the direction of thunderstorm movement. We investigated the basic performance of the magnetic field measurement system composed of multi-turn loop-type sensors, the differential amplifier and active integrator. As a result, the response characteristics of the magnetic field sensor system to sinusoidal signals was excellent. The frequency bandwidth ranges from about 1 kHz to 500 kHz, the response sensitivity was 0.16mV/nT. In addition, we proposed the algorithm that determines the direction of lightning discharges using the comparison of the output signals of right-angled loop-type magnetic field sensors. The accuracy of the direction finding of lightning discharges is fairly well within the measurement error of less than $5^{\circ}$. The magnetic field measurement system proposed in this work can be used to track the direction of thunderstorm movement.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.98-105
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• 2014

Soil discharges near the ground rod play an important role to reduce the ground potential rise and the ground impedance and to help the fault current to spread into the earth. This paper presents the effects of soil discharges on the transient and conventional ground impedances when the lightning impulse voltage was applied to a ground rod with radial needles. The current-voltage (I-V)curves and transient ground impedance curves were calculated based on the measured current and potential traces. Soil discharge behaviors related to I-V curves and transient ground impedance curves were analyzed as a function of the magnitude of lightning impulse voltages. As a result, the soil discharges occurred near the ground electrode contribute to the reduction of conventional ground impedance and limits the ground potential rise effectively under lightning impulse voltages.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1108-1110
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• 1999

This paper describes the comparison results on electrical characteristic changes of ZnO blocks by lightning impulse current. The five types of ZnO blocks used in lightning arrester for distribution lines have been estimated repeatedly till about 400 times by a standard lightning impulse current of 3kA, $8/20{\mu}s$, and changes of the performance characteristics of them to operation times were examined and compared quantitatively every fifty times discharge. It is expected that the result will be useful to diagnose the soundness of ZnO blocks or lightning arresters, and to develope deterioration diagnosis device for them.

• 한국전자파학회논문지
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• 제10권6호
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• pp.917-926
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• 1999

본 논문에서는 운방전에 의해서 방사되는 자장 파형을 측정할 수 있는 루프형 자장 센서를 이용한 계측장 치를 제작하고, 뇌방전과 관측점 사이의 거리측정계를 제안하였다. 정극성과 부극성의 자장 파형에 대한 중첩 펄스의 시간 간격, 영점 교차시간과 백분율 반전답의 깊이 등의 파라미터를 뇌방전 지점과 관측 지점 사이의 거리에 따라 통계적으로 분석하였으며, 그 결과를 요약하면 다음과 같다 운방전에 의해서 발생한 자장 파형 의 파두 부분에는 수 개의 중첩 펄스가 관측되었으며, 이들 펄스 사이의 평균 시간 간격은 약 $4\mu\textrm{s}$이었다. 또 한, 양극성 특성이 명확하게 나타났으며, 백분율 반전답의 깊이는 약 57 -65 %이었다. 뇌방전 지점에서 관측 지점 사이의 거리가 증가할수록 영점 교차시간은 짧아졌다.

• 대한전기학회논문지
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• 제45권2호
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• pp.289-293
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• 1996

The basic study on laser triggered lightning was carried out for the active protection of lightning in power transmission system. The lengths of generated plasma channels were simulated numerically for variations of energy and pulse width of CO$_{2}$ laser by Runge-Kutta-Gill method. As results, the effective lengths of plasma channels were 2.3m, 2.67m and 3.4m respectively for energy of 45J, 60J and 100J of CO$_{2}$ laser pulse with pulse width of 50nsec using focusing mirror with focal length of 10m. And also the effects of pulse width of first pulse and tail pulse of CO$_{2}$ laser on the length of plasma channel were examined.