• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.49-56
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• 2011

Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents or transient currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the grounding resistance, grounding impedance and transient grounding impedance are measured by using 3-point fall-of-potential method in order to analyse grounding characteristics of the copper and concrete rod grounding electrodes. An equivalent transfer function model of the ground impedance and transient grounding impedance are identified from the measured values by using ARMA method and evaluated by comparing the conventional grounding impedance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.145-151
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• 2004

The purpose of isolated grounding system is to protect own electrical facilities from the other grounding systems in order to avoid the potential interference between ground grid areas. But the physically close distances involved could lead to potential interference problems. The simplified equation for determining potential interferences based on the measured data under the case study grounding system is proposed in this paper. The results obtained with the equation to verify the accuracy have been compared with the results obtained from the CDEGS program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.97-104
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• 2001

The effects of the position of potential probe on the measurements of the ground resistance in the fa11-of-potential method are described. The ground resistance is theoretically calculated by applying the 61.8[%] rule, and then the potential probe is located on the straight line between the grounding electrode to be measured and the current probe. However, sometimes the grounding electrode to be measured and the measuring potential and current probes in on-site test might not be arranged on the straight line with adequate distance because there are building, roadblock construction and other establishments. Provided that the grounding electrode to be measured and the measuring potential probes are out of position on the straight line, the measurement of the ground resistance classically falls into an error and the measured ground resistance should be corrected. In this work, measurements were focused on the grounding electrode system made by the ground rods of 2.4 m long. The measuring error was increased with increasing the angle which is made by the 3-points of the grounding electrode to be measured, the potential anti current probes, and it was a negative. That is, all of the measured ground resistances ware less than the true ground resistance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.49-54
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• 2005

Measuring ground resistance is a typical way of performance evaluation of a grounding electrode. Among various ground resistance measurement methods, FOP (Fall-Of-Potential) method has been widely used, especially in case of a relatively large grounding electrode such as a substation grounding mesh grid Since FOP measurement line has to be increased as the size of grounding electrode increases, however, it is often that securing long enough FOP-line is practically impossible. In this paper, a sophisticated interpretation method of FOP measurement ma which is applicable to large grounding electrode networks, is presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.95-99
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• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection systems is presented. The measurement and analysis of ground impedance are based on a computer aided technique. The magnitude and phase of ground impedance were measured and analyzed by the modified fall-of-potential method and the proposed computer program algerian using the waveforms of the test current and potential rise. The theoretical analysis of ground impedance were performed with the equivalent circuit models, and the theoretical results were compared with the measured data.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.211-215
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• 2008

This paper deals with the transient ground impedance of small-sized needle-rod installed in a test field, Impulse voltage generator was used to inject lightning impulse on a ground electrode and modified fall-of potential method was proposed to measure the high ground potential rise. Transient ground impedance was analysed with impedance curve and I-V curve as respects the resistivity of soil. Soil ionization near the ground electrode is activated in high resistivity soil and have an effect on the reduction of transient ground impedance significantly.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.71-74
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• 2003

Fall-of-potential method is used usually to measure the ground impedance of large scale grounding system exactly. Because the interlinked magnetic flux between closed loops to inject test current and to measure potential rise is existed in E-P-C straight line arrangement, mutual(or inductive) coupling influences greatly on the measurement correctness. Measurement errors produced from inductive coupling could be reduced by the arrangement methods of auxiliary electrodes. Right angle or P-E-C order arrangement methods were effective to reduce the inductive coupling and the decrease degree of measurement error was analysed as quantitative through an experiment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.415-417
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• 2009

3점 전위 강하법을 이용하여 접지 저항을 측정하는 방법은 접지 전극과 전류 전극 그리고 전위 전극의 이격 거리 영향 관계에 따라 그 정확성이 결정된다. 하지만 실체 접지 시설을 요하는 현장에서 접지 저항을 측정하기 위한 공간 확보가 어려워 각 전극들의 정확한 위치 선정이 여의치 않는 경우가 발생할 수 있다. 이에 본 논문에서는 전위 전극의 이탈 범위와 접지 전극으로부터의 이격 거리에 따른 접지 저항 값의 오차를 측정하여 각각의 경우에 대해 통상적인 접지 저항 측정 방법에 의한 측정값과의 오차 범위를 분석해본다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.382-386
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• 2001

Presently, typical maximum probe spacing of soil resistivity survey(Wenners 4 pin method) is 20 m in case of 154 K substation grounding design of KEPCO. This paper examined the effects of maximum probe spacing of wenner method on the equivalent soil modeling and the accuracy of grounding resistance measurement by comparing the calculated FOP(Fall-of-Potential) curves of various soil models with the measured one at 154kV H substation. The comparison results showed that the inaccurate estimation of deep soil resistivity, which is caused from the short probe spacing of soil resistivity survey, can produce large errors on measurement of grounding resistance. In this paper a quantitative analysis of FOP at H substation has been presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.51-56
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• 2005

Ground resistance measurement is an elementary technique for the evaluation of grounding system. There are main environmental factors to consider for correct measurement, but the problem is that it is practically most cases to measure ground resistance unable to know the factors. This paper presents a methodology toward true value of resistance in the unknown circumstance, utilizing the defined term, 'variation rate' of potential difference curve appearing in the distance to a current probe as in the three point fall-of-potential method which comprises the characteristics of environmental factors. This methodology is a induced result from the previous demostrated studies.