휴대용 극저주파 전장측정기 개발

길경석,송재용,김일권 한국센서학회 2000 센서학회지 Vol.9 No.2

This paper dealt with the developed portable electric field meter which consisted of planar-type sensor, analog amplifier with gain controller, A/D convertor, and display unit. The principle of the planar-type sensor for detecting time-varying electric field of extremely low frequency (ELF) bandwidth was described, and a calibration system using cylindrical guard electrodes and parallel-plate electrodes was proposed. From the calibration experiment, the frequency bandwidth and the sensitivity of the developed electric field meter was 17 [Hz) ∼ 7 [kHz], and 4.45 [mV/V/m], respectively. Also it can measure the electric field strength up to 10 [kV/m], and the measured result was displayed on the liquid crystal display in digit. The electric field meter can be widely applied to measure electric field strength radiated from power lines, computers, and home appliances such as hair dryer, heater, etc..

부분방전에 의한 음향신호의 검출과 위치추정에 관한 연구

길경석,박대원,김일권,최수연,박찬용,Kil, Gyung-Suk,Park, Dae-Won,Kim, Il-Kwon,Choi, Su-Yeon,Park, Chan-Yong 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.10

This paper dealt with the frequency spectrum analysis of acoustic signal produced by partial discharge (PD) in insulation oil and the positioning of PD occurrence to apply in diagnosis of oil insulated transformers. Three types of electrode system ; the needle-plane, the plane-plane, and the wire-wire structure were assembled to simulate partial discharges in oil insulated transformers. A low-noise amplifier and a decoupling circuit were designed to detect acoustic signal with high sensitivity The frequency spectrum of the acoustic signal were 50 kHz ${\sim}$ 260 kHz in the needle-plane, 50 kHz ${\sim}$ 250 kHz in the plane-plane, and 45 kHz${\sim}$195 kHz in the wire-wire electrode system. Their peak frequencies were 145 kHz, 130 kHz and 114 kHz, respectively The position of PD occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission (AE) sensors, and we could find the position within the error of 1 % in the experimental apparatus.

SF6 가스절연에서 부분방전의 특성분석

길경석,김선재,왕국명,박서준,안창환 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.7

This paper deals with the characteristics of partial discharge(PD) for the purpose of a condition based maintenance(CBM) of gas insulated switchgears(GIS) in power equipment. Four types of electrode systems such as a protrusion on enclosure(POE), a particle on spacer(POS), a free particle(FP) and a Floating were designed and fabricated. PD pulses were measured using UHF sensor with a frequency range of 300MHz∼1.4GHz and a DAQ with a sampling rate of 250MS/s. Discharge inception voltage(DIV), discharge extinction voltage(DEV), and phase resolved partial discharge(PRPD) were analyzed depending on electrode systems. The average DIV in the POS was 28.8kV. It was about 1.7 times higher than that in the FP, which was the lowest value of 17.2kV. The FP shuffled and jumped at the applied voltage of 23.5kV. Over 95% of PD pulses in the POE were generated in the negative polarity(181°∼360°) of applied voltage. The results showed the phase(Φ)-magnitude(dBm) of PD pulses by UHF sensor, a cluster was formed separately depending on electrode systems. 본 논문에서는 GIS의 상태진단을 위한 목적으로 SF6 가스절연구조에서 부분방전의 특성에 관하여 기술하였다. 외함 돌출(POE), 스페이서 파티클(POS), 자유입자(FP) 및 부유입자(Floating) 등 4종의 전극계를 설계 및 제작하였다. UHF 센서(300 MHz∼1.4 GHz)와 DAQ(250 MS/s)를 사용하여 부분방전 펄스를 검출하였다. 전극계별 방전개시전압(DIV), 방전소멸전압(DIV) 및 PRPD를 분석하였다. 평균 방전개시전압은 스페이서 파티클이 28.8 kV로 4종의 전극계 중 가장 높았다. 이것은 17.2 kV의 자유입자 보다 약 1.7배 높은 값이다. 자유입자는 인가전압 23.5 kV에서 셔플과 점핑을 병행하였다. 외함 돌출은 인가전압의 부극성(181°∼360°)에서 부분방전 펄스가 95% 이상 발생하였다. 부분방전 펄스의 위상(Φ)과 크기(dBm)의 상관관계를 분석한 결과, 전극계의 형태에 따라 클러스터가 개별적으로 분포하였다.

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%.

LED-해양 IT 융합기술

길경석 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.4

LED의 해양산업응용

길경석 한국마린엔지니어링학회 2012 한국마린엔지니어링학회 학술대회 논문집 Vol.2012 No.10

파뢰기의 열화진단 전문가 시스템 개발에 관한 연구

길경석,김명진,한주섭 한국해양대학교 산업기술연구소 2002 연구논문집 Vol.19 No.-

This paper describes with an effect of a single- and a quadruple- lightning impulse currents on electrical characteristics of ZnO blocks, and an expert system to diagnose deterioration of arresters. In this study, an accelerated deterioration test is carried out to deduce the parameters needed for diagnosing arrester deterioration, and leakage current components are measured. Also, wave height distribution of the leakage current with the progress of arrester deterioration is analyzed. From the experimental results, the wave height distribution of the leakage current showed a conspicuous difference even in an immaterial leakage current increase. The use of wave height distribution of the leakage current in deterioration diagnostic technique makes more accurate diagnosis than the conventional method using only a leakage current value. Finally, the expert system based on the experimental reslts is developed, and the effectiveness of the system is estimated in a 18[kV] lightning arrester.

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.

방사선 펄스 계측 및 분석시스템에 관한 연구

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

An objection of this study is to develop a measuring circuits and a analytic system for radioactive pulses. The proposed system consists of a pulse detection units for neutrons and gamma-rays, a programmable high voltage supply unit and a digital signal processor. Gamma-ray detection circuit can count pulse up to 10,000[pps]. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60[dB], and its frequency bandwidth is from 37[Hz] to 300[kHz]. Also, pulse height distribution in accordance with pulse counts is important data in analyzing radioactive pulses. In this study, A/D converter (12[bit], 100[ns] and DSP [TMS 320C31-60) are used to analyze the pulse height, and the analytic system is designed to be operated in PC-base. Radioactive pulse has superior penetration ability to all kind of materials, and it is also possible to evaluate the soundness of electrical insulation materials by analyzing the pulse counts and/or pulse height distribution.

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.