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SF<sub>6</sub>-N<sub>2</sub> 혼합가스 중 돌출 결함의 부분방전 특성
조향은,왕국명,김선재,박경수,길경석,Jo, Hyang-Eun,Wang, Guoming,Kim, Sun-Jae,Park, Kyoung-Soo,Kil, and Gyung-Suk 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.1
Studies on a $SF_6$-mixture and -alternative gas has been in progress to reduce the use of $SF_6$ gas as an insulation material of GIS (gas insulated switchgears). In this paper, we dealt with PD (partial discharge) characteristics in pure $SF_6$ and $N_2$, 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 $SF_6-N_2$ mixtures ($SF_6$ 100%, $SF_6$ 80%-$N_2$ 20%, $SF_6$ 50%-$N_2$ 50%, $SF_6$ 20%-$N_2$ 80%, and $N_2$ 100%) according to the IEC60270. The DIV, DEV as well as magnitude of PD pulse decreased on the POC as increase of $N_2$ ratio. For the POE, the DIV and DEV in $N_2$ ratio below 50% were the same voltages as those in $SF_6$ 100%. In this experiment, $SF_6$ 80%-$N_2$ 20% mixture could be considered with the equivalent insulation performance to a GIS.
박경수,왕국명,황성철,김선재,길경석,Park, Kyoung-Soo,Wang, Guoming,Hwang, Seong-Cheol,Kim, Sun-Jae,Kil, Gyung-Suk 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.10
This paper dealt with the deterioration characteristics and an on-line diagnosis equipment for SPDs (surge protective devices). An accelerated aging test was carried out using a $8/20{\mu}s$ standard lightning impulse current to analyze the changes of electrical characteristics and to propose the diagnostic parameters and the criterion for deterioration of ZnO varistor which is the core component of SPDs. Based on the experimental results, an on-line diagnosis equipment for SPD was fabricated, which can measure the total leakage current, reference and clamping voltage. The leakage current measurement circuit was designed using a low-noise amplifier and a clamp type ZCT. A linear controller, the leakage current measurement part and a HVDC were used in the measurement of reference voltage. The measurement circuit of clamping voltage consisted of a surge generator and a coupling circuit. In a calibration process, measurement error of the prototype equipment was less than 3%.
김우현,왕국명,길경석,지홍근,Kim, Woo-Hyun,Wang, Guoming,Kil, Gyung-Suk,Ji, Hong-Keun 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.6
Most series arcs lead to electrical fires that cannot be interrupted by circuit breakers, because the arc's current is outside the breaker's operating range. In this paper, experiments were conducted on the detection and identification of series arcs to prevent electrical fires. Plugs and outlets specified in KS C 8305 were deteriorated to replicate arc faults commonly found in fields. The characteristics of series arcs resulting from various types of loose connections were determined by analyzing the frequency spectra and phase distributions of detected arc pulses. The results showed that the simulated arc defects used in this study were more similar to actual arc phenomena than the existing arc generator specified in UL 1699. In addition, loose connections, such as wire-wire, terminal-wire, and outlet-plug, can be identified by phases of $0^{\circ}$, $180^{\circ}$ and $360^{\circ}$, respectively. These phases can be detected by a band pass filter with a frequency range of 5~10 MHz, which can be used as the trip signal for circuit breakers.
SF<sub>6</sub> 가스절연에서 부분방전의 특성분석
김선재,왕국명,박서준,길경석,안창환,Kim, Sun-Jae,Wang, Guoming,Park, Seo-Jun,Kil, Gyung-Suk,An, Chang-Hwan 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 300 MHz~1.4 GHz and a DAQ with a sampling rate of 250 MS/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 28.8 kV. It was about 1.7 times higher than that in the FP, which was the lowest value of 17.2 kV. The FP shuffled and jumped at the applied voltage of 23.5 kV. Over 95% of PD pulses in the POE were generated in the negative polarity ($181^{\circ}{\sim}360^{\circ}$) of applied voltage. The results showed the phase (${\Phi}$)-magnitude (dBm) of PD pulses by UHF sensor, a cluster was formed separately depending on electrode systems.
윤민영,박경수,왕국명,김선재,길경석,Yun, Min-Young,Park, Kyoung-Soo,Wang, Guoming,Kim, Sun-Jae,Kil, Gyung-Suk 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.2
This paper dealt with the propagation characteristics of acoustic signal in insulation oil for the purpose of improving the reliability of AE (acoustic emission) method used for condition monitoring of oil-immersed transformers. A discharge source was placed in insulation oil and AE sensors ($f_c$ :140 kHz) were attached on the oil tank to study the changes of velocity and propagation path with the depth and distance. The average velocity was 1,436 m/s and the velocity decreased with the increase of depth from the oil surface to 430 mm. The propagation paths were classified into three sections by the shortest reflection path of the detected signal. The minimum distinguishable distance in each section was 70 mm. It was also verified that PD (partial discharge) with a magnitude over than 500 pC can be detected by the AE sensors.
부분방전에 의한 SF<SUB>6</SUB> 가스의 특성변화
황성철(Seong Cheol Hwang),왕국명(Guoming Wang),길경석(Gyung Suk Kil) 한국철도학회 2017 한국철도학회 학술발표대회논문집 Vol.2017 No.05
가스절연개폐장치(Gas insulated switchgear, GIS)에서 결함이 발생하면 절연이 파괴되고 대형 정전사고로 이어지므로 이를 예방하기 위한 각종 진단기술이 활용되고 있다. 가장 일반적인 방법은 부분방전(Partial Discharge, PD)을 검출하는 것이지만, GIS의 절연매체인 SF6가스(Sulfur Hexafluoride Gas) 특성변화에 대한 연구는 이루어지지 않고 있다. 본 논문에서는 부분방전을 발생시키고 PRPD(Phase Resolved Partial Discharge)와 SF6가스 특성 파라미터를 분석하였다. 방전시간이 지속됨에 따라 초기상태 대비 평균방전크기, 방전 횟수, 압력 및 밀도의 변화를 비교하였다. The defects existing in the gas-insulated switchgear (GIS) cause insulation breakdown and consequent outage. Various diagnostic techniques have been applied to prevent these accidents. The most widely used method is the diagnostic of partial discharge (PD) that generates from the defects. However, few researches has been carried out to study the characteristic changes of Sulfur Hexafluoride (SF6) gas, which is the insulation medium of GIS. In this paper, partial discharge was generated and the phase resolved partial discharge(PRPD) and parameters of SF6 gas were analyzed. The average discharge magnitude, pulse count, gas pressure and density in a specific period were compared with that of the initial state.