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        • KCI등재

          온도측정에 의한 산화아연형 피뢰기 진단

          길경석,문승보,박태곤,한주섭,송재용,서황동 대한전기학회 2005 전기학회논문지C Vol.54 No.8(C)

          In this paper, surface temperatures of ZnO arresters as a function of ambient temperatures and leakage currents were experimentally investigated. The variations of the leakage current was below 10㎂, which comes about 4.5% of the normal leakage current. Temperature differences between the ambient and the surface of arresters were not shown until 150% to the normal leakage current, and were remarkable over 200%.From the results, we deduced a couple of polynomials which enables the calculation of the leakage current by the measurement of surface temperature. Tests on used arresters have shown the same results as the experimental one. Also, we expect that an arrester diagnosis is possible by measuring the surface temperature of them after more studies on the effect of wind, moisture penetration, and arrester types.

        • KCI등재

          부분방전에 의한 주계전기의 절연성능 평가

          길경석,김일권,박대원,송재용,이강원,조은제 한국철도학회 2007 한국철도학회논문집 Vol.10 No.4

          A new dielectric test on main relays of electric traction vehicles, the partial discharge(PD) test, is proposed. The PD test will not affect the insulation performance of specimen during the test and provide much more detailed information on insulation, the types of defects, and so on. Insulation performance of relays is estimated by discharge inception voltage(DIV), discharge extinction voltage (DEV), and apparent charge as a function of test voltage and time. Three main relays of different manufacturing date were estimated by applying AC voltage with three patterns in ranges of 0~1,200[V]. From the results, we could estimate insulation state and which types of defects exist in them.

        • KCI등재

          가스절연개폐기에서 용량성 전압프로브를 이용한 부분방전의 측정

          길경석,박대원,최수연,김일권,박찬용,Kil,,Gyung-Suk,Park,,Dae-Won,Choi,,Su-Yeon,Kim,,Il-Kwon,Park,,Chan-Yong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.1

          An objective of this paper is to develop a partial discharge (PD) measurement device for monitoring gas insulated switches installed in power distribution system. A capacitive voltage probe was studied and designed to detect PD pulse without an electrical connection. The PD measurement device consists of the capacitive voltage probe attached outside of a bushing, a coupling network which attenuates AC voltage by 270 dB, and a low noise amplifier with the gain of 40 dB in ranges of 500 kHz${\sim}$20 MHz. The sensitivity of the prototype device calculated by a calibrator was 1.98 m V /pc. An application experiment was carried out in a 25.8 kV gas insulated switch and the peak pulse of 76.7 pC was detected. From the experimental results, it is expected that the PD measurement device can be applied to online monitoring system of gas insulated switches.

        • KCI등재

          유중 부분방전의 음향검출에 관한 연구

          길경석,김성욱,박대원,김선재,송재만,Kil,,Gyung-Suk,Kim,,Sung-Wook,Park,,Dae-Won,Kim,,Sun-Jae,Song,,Jae-Man 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.1

          This paper dealt with the acoustic detection of partial discharge (PD) in insulation oil for insulation diagnostics of oil immersed transformers. Electrode systems such as needle to plane, plane to plane, and floating were fabricated to simulate some defects in transformers. A wide band acoustic emission(AE) sensor with the frequency ranges of 100 kHz~1 MHz and a narrow band AE sensor with the resonant frequency of 140 kHz were used in the experiment. Also, a decoupler and an amplifier were designed to detect and amplify the acoustic signal only. The decoupler separates acoustic signal from DC source without any distortion, and the amplifier has the gain of 40 dB in frequency ranges of 11 kHz~4 MHz. In the experiment, frequency components and propagation characteristics of acoustic signal were analyzed, and an algorithm of positioning of PD occurrence by the time difference of arrival was proposed. From the results, the frequency components of the acoustic signal exist from 50 kHz to 200 kHz and the positioning error of PD calculated by three AE sensors was within 1%.

        • KCI등재

          직류전동차 탑재용 피뢰기의 최적선정에 관한 연구

          길경석,류길수,송재용,김일권,박대원,한문섭 한국철도학회 2007 한국철도학회논문집 Vol.10 No.2

          In this paper, we proposed a selection and application recommendations of ZnO arresters for DC electric traction vehicles. To decide the Continuous Operating Voltage(UC), the Rated Voltage(Ur), and the Nominal Discharge Current(In), we measured and analyzed system voltages and surge currents flowing the arrester installed on a DC electric traction vehicle under running state. System voltages measured up to 1,800V in 1,500V-system, and surge currents were recorded up to 3 times per a running-service-route and their magnitudes were ranges of 150A~2kA. From these results and a standard EN50163, we could proposed UC, Ur, and In available for the 1,500VDC electric traction vehicles.

        • KCI등재

          광대역 접지임피던스 측정기의 설계 및 제작

          길경석,박대원,장운용,한주섭,길형준,Kil,,Gyung-Suk,Park,,Dae-Won,Jang,,Un-Yong,Han,,Ju-Seop,Gil,,Hyoung-Jun 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

          The basic performance of the ground system is evaluated as the ground resistance by applying low frequency current below 1 kHz. However, characteristics of the ground system should be analyzed by high frequency current up to 1 MHz since transient currents having a few hundred kHz component flow during a line-to-ground fault and/or a lightning strike. This paper deals with the design and fabrication of a wideband ground impedance meter (WGIM) which measures the impedance of ground systems in ranges from 65 Hz to 1.28 MHz. Also, a noise elimination algorithm using a digital bandpass filter is proposed. The maximum error of the WGIM is 4.91% in the measurement frequency range.

        • KCI등재

          복합차체의 낙뢰에 대한 인체 안전성 분석

          길경석,박대원,김성욱,박찬용,조영진,Kill,,Gyung-Suk,Park,,Dae-Won,Kim,,Sung-Wook,Park,,Chan-Yong,Cho,,Young-Jin 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.6

          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/$20{\mu}s$ 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 em distant was 175 V at 37.67 kA, and it corresponds to 875 V between 1 m distant. The amount of charge flowing a passenger at 100 kA impulse current can be estimated to $0.31\;mA{\cdot}s$. This is much less than the limit amount of charge for human body, $30\;mA{\cdot}s$ which is presented by Koeppen and Osypka.

        • 스파크 신호검출에 의한 전기화재 예측

          길경석,김일권,송재용 한국해양대학교 산업기술연구소 2002 연구논문집 Vol.19 No.-

          This paper describes a technique that can predict electric fires by detecting a spark signal generated from operation of electric facilities. An electric fire lead a loss of life as well as huge property, therefore it is very important to predict an electric fire and eliminate the causes of it. Electrical spark which is ranked as majority causes of electric fires has a characterized frequency bandwidth distinguished from power frequency. In this experiment, various spark signals are simulated in a condition such as short circuit, flashover, and surface discharge. The results showed that the monitoring of spark signals can predict electric fires.

        • KCI등재

          SF6-N2 혼합가스 중 돌출 결함의 부분방전 특성

          길경석,조향은,왕국명,김선재,박경수 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.1

          Studies on a SF6-mixture and -alternative gas has been in progress to reduce the use of SF6 gas as an insulation material of GIS (gas insulated switchgears). In this paper, we dealt with PD (partial discharge) characteristics in pure SF6 and N2, and their mixtures on aspects of insulation design and risk assessment for GIS. A POC (protrusion on conductor) and a POE (protrusion on enclosure) as the major defects were fabricated to simulate PD. We analyzed the DIV (discharge inception voltage), DEV (discharge extinction voltage), pulse magnitude, counts and phase distribution of PD pulse in SF6-N2 mixtures (SF6 100%, SF6 80%-N2 20%, SF6 50%-N2 50%, SF6 20%-N2 80%, and N2 100%) according to the IEC60270. The DIV, DEV as well as magnitude of PD pulse decreased on the POC as increase of N2 ratio. For the POE, the DIV and DEV in N2 ratio below 50% were the same voltages as those in SF6 100%. In this experiment, SF6 80%-N2 20% mixture could be considered with the equivalent insulation performance to a GIS. 가스절연개폐장치(GIS)의 절연재료인 SF6의 사용량 감소를 위해 혼합 및 대체 가스에 대한 연구가 활발히 진행되고 있다. 본 논문에서는 GIS의 절연설계와 위험도 평가면에서 SF6, N2 및 SF6-N2 혼합가스에서의 부분방전 특성에 대해 연구하였다. 부분방전을 모의하기 위하여 GIS 내부에 발생하는 주요 결함인 도체돌출(POC) 및 외함돌출(POE)을 제작하였다. SF6-N2 혼합가스(SF6100%, SF680%-N220%, SF650%-N250%, SF620%-N280%, and N2100%) 중에서 방전개시전압(DIV), 방전소멸전압(DEV), 펄스 크기(q), 펄스 수(n) 및 위상분포(Φ)를 IEC 60270에 따라 분석하였다. POC는 N2 비율이 증가함에 따라 DIV와 DEV 및 펄스크기가 감소하였다. POE에서 N2 비율이 50% 이하일 때에는 DIV와 DEV가 각각 SF6100%일 때와 거의 동일하였다. 본 실험 결과, SF680%-N220% 혼합비는 SF6와 동일한 절연성능을 유지하면서 GIS에 적용을 고려할 수 있을 것으로 본다.

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