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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.
다양한 전류원에 대한 접지시스템의 위험전압 측정과 분석
吉暻碩(Gyung-Suk Kil),文秉斗(Byoung-Doo Moon),金晃局(Hwang-Kuk Kim),朴大元(Dae-Won Park),吉亨准(Hyoung-Jun Gil) 대한전기학회 2009 전기학회논문지 Vol.58 No.1
Grounding systems set the reference voltage level of electric circuits and suppress the Ground Potential Rise (GPR) by flowing fault currents to the ground safely. There are several parameters which evaluate the performance of grounding systems as ground resistance, touch voltage and step voltage. The touch and step voltages, which is called "risk voltage", are especially important to ensure the safety of human body. This paper dealt with the influence of current sources with the different frequency components on the touch and the step voltages. Three types of current sources as commercial frequency, square wave, and surge with the fast risetime of 50 ㎱ ~ 500 ㎱ were used to analyze the risk voltages in a grounding system. The risk voltages showed remarkable difference in the same current amplitude depending on the current sources, and increased linearly with the current amplitude in the same current source. From the experimental results, it was confirmed that the risk voltages can be evaluated by a small current application in large-scale grounding systems and the possible largest risk voltage can be calculated by a surge current with the risetime of 200 ㎱ or a current source with the same frequency component as the surge current.
길형준(Hyoung-Jun Gil),김동우(Dong-Woo Kim),김향곤(Hyang-Kon Kim),길경석(Gyung-Suk Kil) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.10
In order to assess the characteristics of transient ground impedance according to the injection of lightning impulse currents in grounding system, the portable transient ground impedance meter has been designed and fabricated. The portable transient ground impedance meter, which produces impulse current with fast rising time of 5O~500[㎱], can measure the transient ground impedance. The field test was carried out to evaluate the portable transient ground impedance meter at grounding electrodes for lightning protection. The transient ground impedances strongly depend on the rising time of applied voltage, but are nearly constant in magnitude of applied voltage.
길형준(Hyoung-Jun Gil),김동우(Dong-Woo Kim),이기연(Ki-Yeon Lee),문현욱(Hyun-Wook Moon),길경석(Gyung-Suk Kil) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
There are several parameters which evaluate the performance of grounding systems as ground resistance, touch and step voltage. The touch and step voltages, which is called "risk voltage", are especially important to ensure the safety of human body. In order to assess the risk voltage according to the injection of fault currents in grounding system, the risk voltage measuring system has been designed and fabricated. The system consists of a variable frequency power source, 16-bit and 16-input analog-digital converter, a signal processor, 6-auxiliary electrodes, and software. The power source generates sine-wave voltage up to 300[V<SUB>rms</SUB>]. The system measures ground potential differences at up to 6-locations and calculates the parameters by proposed algorithms. The risk voltage measuring system can be used to access the grounding system in new method.
현장조사를 통한 건축물 접지저항 측정용 전극 설치의 개선에 관한 연구
길형준(Hyoung-Jun Gil),김동우(Dong-Woo Kim),길경석(Gyung-Suk Kil) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.5
This paper deals with the improvement of electrode installation for measurement of ground resistance through investigation on the spot in buildings. The investigation was carried out for an earthing terminal board for measurement of ground resistance, installation of auxiliary electrode, etc. The criteria value is set up by measuring method of ground resistance in international standard. In case of inadequate installation of auxiliary electrode, a relative error is analyzed and adequate installation method of auxiliary electrode is proposed. As a consequence, it is necessary to write direction of ground and equipment, and separate auxiliary electrode for measurement of ground resistance in order to minimize measuring error.
진창환(Chang-Hwan Jin),박대원(Dae-Won Park),서재석(Jae-Seok Seo),길경석(Gyung-Suk Kil),길형준(Hyeong-Jun Gil) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
In measurement of risk voltages; the step and touch voltage the distance between the current electrode and the ground electrode recedes up to several hundred meters as the scale of grounding system increases. This paper dealt with the measurement method of risk voltage in a restricted space. The risk voltage was analyzed depending on the distance and the direction of the current electrode from the ground electrode in a 10 [m] * 10 [m] mesh grounding system. The average value of risk voltages measured at a point 20 [m] away from the current electrode was deviated below 5 [%] from that measured at 100 [m] point. Consequently the evaluation of risk voltage of a large-scale grounding system buried in a spatially restricted place is available if the current electrode is installed in symmetry to the ground electrode.