• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.480-483
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• 1997

This paper describes dielectric characteristics and discharge development mechanisms of SF$_{6}$ gas stressed by very fast transient overvoltages in inhomogeneous electric field. Predischarge phenomena of SF$_{6}$ gas in non-uniform fields are statistically investigated with positive and negative very fast trannsient overvoltages. It was confirmed that all of the predischarges of the positive and negative polarities develop in a regime of stepwise leader extension. i.e, the predischarge developments leading to breakdown against very fast transient overvoltages are similar to the non-oscillating impulse voltages.ges.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1523-1525
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• 1994

This paper describes a proposed very fast transient overvoltages(VFTO) measurement system suited for established gas insulated switchgear(GIS). The detecting system consists of a shield electrode connected to a buffer amplifier, and the transmission of the detected signal to an oscilloscope is made through an optical fiber. The bandwidth of the measurement system is 5 Hz to 30MHz. When determining the voltage dividing ratio by use of the commercial frequency voltage, the error is less than 0.5 %. Also, the data were obtained by the electric field probe and the high voltage probe, and their deviation for voltage dividing ratio were less than 1 %.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.519-520
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• 2011

In Gas Insulated Substation(GIS), Very Fast Transient Overvoltages(VFTOs) are generated by the switching operation of disconnector or circuit breaker and it is propagated to each component of GIS. Each component of GIS is modeled by lumped line model and distributed line model based on equivalent circuits. The various cases which can be operated and the various closing point-on-wave are considered. In this paper, magnitude and rate-of-rise of VFTO are simulated and analyzed by comparing the simulation results. Measurements are performed at transformer and circuit breaker.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.334-337
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• 1997

This paper describes dielectric characteristics of SF$_{6}$ gas stressed by the non-oscillating and oscillating impulse voltages in inhomogeneous fields disturbed by metallic protrusion. The breakdown voltage-time (V-t) characteristics and breakdown voltage-gas pressure (V-p) characteristics and their characteristics are statistically investigated with positive and negative very fast transient overvoltages. The experiments were carried out using a needle-to-plane gap geometry in the gas pressure ranges from 0.1 to 0.5 MPa. The gap separation gas 22 mm, and the needle-shaped protrusions were made of stainless steel 10 mm in length and 1.0 mm in diameter.r.

• E2M - 전기 전자와 첨단 소재
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• 제9권4호
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• pp.385-395
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• 1996

이 논문은 금속성 돌기물에 의한 불평등전계중에서의 비진동성과 진동성 임펄스전압에 의한 SF$_{6}$ 가스의 절연파괴 특성에 대해 기술하였다. 절연파괴전압-시간특성을 가스압 0.1-0.5MPa의 범위에서 정.부 극성의 전압을 인가하여 측정하였으며, 그리고 50.ohm.분류기를 통해서 전구방전 전류를 관측하였다. 가스압력에 의한 리이더 진전시간의 의존성도 측정하였다. 스트리머 코로나에 의해 발생하는 공간전하에 의한 국부전계강화는 시험갭의 전기적 절연파괴에 영향을 미치는 것으로 판명되었다. 절연파괴는 초기 스트리머 코로나로부터 발단되어, 국부전계강화에 의한 리이더진전으로 이루어진다.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.90-99
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• 2004

고도 정보화 사회의 발달과 함께 정보통신 설비는 빠른 전송속도를 필요로 하며, 지능형 산업설비와 행정, 금융, 교통시스템과 같은 사회시스템은 집적회로와 초소형 반도체로 구성되므로 원격감시, 조작에 의해 점차적으로 자동화 되어가고 있다. 이와 같은 현대의 초소형 전자회로는 뇌 서지에 의해 흔히 손상을 입을 수 있으며, 뇌 과전압으로부터 전자회로의 보호에 관심이 집중되고 있다. 본 논문은 일반주택에서 뇌 서지로부터 초소형 컴퓨터와 같은 전자기기의 효과적인 보호방법을 제안하기 위하여 전원계통의 접지방식에 따른 서지보호기의 보호효과를 실험적으로 분석하였다. 또한 서지보호기의 효과적인 설치방법을 조사하고 제안하였다. 기존의 설비에 추가적으로 서지보호기를 설치하는 것은 서지보호기까지의 긴 접속선으로 인한 인덕턴스 때문에 높은 잔류전압이 나타난다. 서지보호기의 설치에 있어 두 접속선을 꼬는 방법이 급격하게 상승하는 과도과전압에 매우 효과적이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1520-1522
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• 1994

The clarification of insulation capability of GIS(Gas Insulated Substation) under very fast transient overvoltages such as disconnector/circuit-breaker induced surge is very important for establishing not only a rational insulation testing method, but also insulation design intending to make GIS more reliable and more minimized. One of the absolute prerequisits for this is that more accurate measurement of VFTO. This describes capacitive voltage measuring methods for high voltage steep-footed oscillating waves using capacitive coupling principle and their systems including source and load impedances. Time domain response of unit step and its frequency characteristics are also investigated.