• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.117-123
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• 2011

Lightning and switching surges propagating through the grounding conductors lead to transient overvoltages, and electronic circuits in information technology systems are very susceptible to damage or malfunction from the electrical surges. Surge damages or malfunctions of electrical and electronic equipment may be caused by potential rises. To solve these problems, it is very important to evaluate the ground surface potential rises and hazardous voltages such as touch and step voltages at or near the grounding systems energized by electrical surges. In this paper, the performance of grounding systems against the surge current containing high frequency components on the basis of the actual-sized tests is presented. The ground surface potential rises and hazardous voltages depending on impulse currents for vertical or horizontal grounding electrodes are measured and analyzed. Also the touch and step voltages caused by the impulse currents are investigated. As a result, the ground surface potential rises, the touch and step voltages near the grounding electrodes are raised and the conventional grounding impedances are increased as the front time of the injected impulse currents is getting faster.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1492-1493
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• 2007

This paper represents the development of national standard(NS) for switching impulse(SI) voltage measuring system rated 500 kV. A traceability of the NS to the international standard could be achieved by the intercomparison test with PTB(Physikalisch-Technische Bundesansalt). According to the IEC 60060-2, a measurement uncertainty was assessed. As a result of the tests, the measurement uncertainty and the characteristics of step response were satisfied with the requisite for NS.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.219-223
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• 2002

Voltage and current signals during impulse tests on transformer are treated as non-stationary signals. A new method incorporating signal-processing method such as Wavelets and courier transform is proposed for failure identification. It is now possible to distinguish failure during impulse tests. The method is experimentally validated on a transformer winding. The wavelet transforms enables the detection of the time of occurrence of switching or failure events. After establishing the time of occurrence, the original waveform is split into two or more sections. The wavelet transform has ability to analysis the failure signal on time domain as well as frequency domain. Therefore, the wavelet transform is superior than courier transform to analysis the failure signal. In this paper, the fact was proved by real data which was achieved.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1770-1772
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• 1997

In this paper, Voltage-time characteristics of lightning impulse and switching surge breakdown in SF6 is studied on the gap and various pressure. The characteristics is categorized into three pattern depending on the configuration of the gap and gas pressure. The properties of the voltage-time characteristics in these patterns are generalized as semi-empirical formula which will be useful in the quantitation voltage evaluation of insulation coordination and the abnormal voltage protection of SF6 insulated power equipment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.12-18
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• 1985

In general the impulse sound sources of underwater generated by electric arc discharge had used static energy of the charged capacitors. The author proposed an underwater arc discharge sound source using secondary voltage of high voltage transformer without capacitors. The arc discharge device was composed of a high voltage transformer and a switching system. The impulse current in the primary turn of the high voltage transformer is controlled by the switching system and inductive current of the secondary turn in the high voltage transformer is used in making impulsive arc discharge. A series of experiment have been carried out to observe the acoustic characteristics of the impulse sound source generated by the arc discharge. The results obtained were as follows: 1. Secondary current at the time of arc discharge keeps after ohm's law in the beginning and the maximum current flows out as soon as arc discharge breaks out. 2. A time difference between a start of applied current and a generation of arc discharge sound is the 3msec and it is generated arc sound when breaking down electric insulation at maximum voltage. 3. The sharper the end of electrodes and the higher the secondary voltage, the higher the sound pressure level. 4. Arc discharge sound was generated even at the distance of 100cm between electrodes and was stably reproductive at the gap of 1cm to 100cm. 5. Electric arc discharge sound wave is a shock wave of pulse-width of 0.15msec and spectral distribution of it is plenty of low frequency components less than 10 KHz.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.276-278
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• 1996

The breakdown Process in large gaps is greatly influenced by the gap geometry. Therefor full scale test are essential for the economical and reliable air insulation design. For switching surge design of 765 kV double circuit transmission line KEPRI is carrying the verifying tests using impulse voltage generator at Gochang test site. In this paper, the intermediate results of verifying tests are presented and the switching surge design criteria of 765 kV transmission tower flashover paths are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.490-493
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• 1999

Due to the miniaturization of electrical components and assembles on signal and telecommunication circuits, transient overvoltages caused by switching operation or lightning surge has become more interesting concern to the field of electrical engineering. This paper describes the development of transient voltage blocking devices (TBDs) that can protect sensitive signal and telecommunication devices from overvoltages. Two kinds of TBDs are designed and tested by using a combination surge generator which can produce the standard impulse current of 8/20${\mu}$s 2.1kA according to the IEC 1000-4-5 standard. From the simulation and experimental reults, it is confirmed that the proposed TBD has an enough protection performance in low insertion loss and tight clamping voltage.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1698-1699
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• 2007

This paper deals with the surge measurement system for low voltage power line of industrial plants. It consists of a capacitive divider, A/D conversion part, signal processing and control part. A FPGA and a DSP board were designed to fast signal processing and control. Also, in order to measure lightning surge and switching surge for a long time, data backup device was applied by using SD memory. A performance of the measurement system was verified through evaluation test using impulse calibration generator.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1774-1777
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• 1996

In this paper, applicability of SI-PD(switching impulse - partial discharge) testing method was put on an attempt as a newly proposed diagnostic method for the underground distribution power cable system in Korea. For this purpose, SI-PD testing equipment was designed, and tests were performed using artificial needle-type defects integrated into the 22.9 kV CN/CV cables in drder to prove its reliability. As a result, arc noises, generated from spark gap, were considerably decreased by use of a pneumatic switch immersed into oil, and artificial needle-type defects were well detected with impulse voltage level under $2U_0$. These results imply that it is likely possible to apply SI-PD measurement method as a the nondistructive test for the 22.9 kV CN/CV cable system in Korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.121-129
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• 2002

The present paper describes a technique for installing an effective grounding grids, the major objective is forced on the experimental evaluation of the performance and characteristics with the arrangement and installation method for grounding grids consisting of the means to protect electric shock, electronics and computerized facilities against lightning, switching and ground fault surges. The study is oriented on two major areas: (1) the analysis of the ground surface potential gradient with the arrangement of grounding grids, (2) the control of the dangerous ground surface potential rise. The experiments wee carried out with the impulse currents as a function of the installation method or arrangement of grounding grids. An installation method of the inclined auxiliary grounding grid was proposed to overcome the drawbacks of equally spared grounding grids, i.e. an appropriate design concept far the installation of grounding grids was found out, It has been shown that the installation of the intwined auxiliary grounding grid can also result in a mere than 50% decrease in the maximum potential gradient on the ground surface and enhance the level of safety for persons and electronic equipments..