• Journal of Magnetics
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• 제22권1호
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• pp.43-48
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• 2017

In order to detect the current flowing through concealed conductor, this paper proposes a new method based on derivative method. Firstly, this paper analyzes the main peak characteristic of the derivative function of magnetic field generated by a current-carrying conductor, and a relationship between the current flowing through the conductor and the main peak of the derivative function is obtained and applied to calculate the current. Then, the method is applied to detect the conductor current flowing through grounding grids of substations. Finally, the numerical experimental and field experiment verified the feasibility and accuracy of the method, and the computing results show that the method can effectively measure the conductor current of grounding grids with low error, and the error is within 5 %.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.807-812
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• 1997

For an equivalent uniform soil model to multiple-layered soil structure, ground depth, which is used in the calculation of equivalent resistivity, should be varied according to the size of grounding area. In case of 150 kV substation grounding design, 15 m of ground depth has been used and 25 m for 345 kV, But applying these ground depths can lead to errors in grounding resistance calculation, and these errors are coming from the poor representation of those depths to real soil resistivities. In this paper, the soil resistivity measurement techniques by Wenner method and grounding resistance calculation results by computer simulation were presented. Case studies contain the area from 3,000 to $30,000\;m^2$ and measuring space from of m to $100{\sim}250\;m$, Based of the computation results, 50 m, 60 m and 80 m of ground depth for less than 30, 40 and 70 m of equivalent hemispherical radius were proposed respectively.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2050-2058
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• 2018

Impulse characteristic of transmission tower grounding grid is needed for lightning protection of transmission line. This paper describes an outdoor experimental test facility established for large-scale grounding grid of transmission tower, made up of four impulse current generators and a circle current return electrode. The amplitude of impulse current is up to 100 kA. The results of the CDEGS simulation and GPR measurement reveal the uniform current distribution in the test arrangement. An impulse test for a square electrode with extended conductors is carried out in condition of three current waveforms with different amplitude. Based on the electrical network model and iterative algorithm method, a calculation model is proposed to simulate the impulse characteristic of large-scale grounding grid considering soil ionization. The curve of impulse resistance against the current amplitude shows the soil ionization both from the simulation and test. Deviation between the simulation and test result is less than 15%.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.145-151
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• 2004

독립접지는 개별적으로 접지를 사용함으로써 다른 접지로부터 영향을 받지 않고 설비를 보호하기 위한 것이다. 한정된 부지 내에 많은 접지극이 존재하면 전위간섭 문제가 발생하게 된다. 본 논문에서는 간섭 전위를 계산하기 위한 간략식을 사례연구 접지 시스템에 적용하여 측정 데이터를 근거로 제안 하였다. 정확도를 알아보기 위해서 제안식에서 얻은 결과와 CDEGS 프로그램으로 구한 결과를 비교하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.231-234
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• 2007

This paper presents an analysis method of transient ground impedance using the lightning impulse and variable frequency currents. The transient ground impedance strongly depends on the configuration and size of grounding electrodes and the shapes of impulse currents, and the inductance of grounding electrodes has a significant affect on the transient impedance of the grounding system. There are some differences between the effective impulse ground impedance which was introduced some papers and the transient ground impedance. The transient ground impedance measured from the peak value of impulse voltage and the peak value of impulse current is more reliable than the effective impulse ground impedance.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 학술대회 논문집
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• pp.293-295
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• 2004

Public utilities adopt the grounding rules ; class I, class II, class III and special class III, and install the grounding electrodes in distribution facilities. To keep the safety of the human and the facilities, Public utilities also manage the value of ground resistance in distribution system biennially. At present the Hook-On meter is normally used to measure the ground resistance although it has ${\pm}5[%]$ measuring error and it can not measure the exact value when the current is over 1[A]. In addition it is very difficult to use the fall-of-potential method in distribution system. In this paper we propose the new measurement method using ground current of distribution system as the current source.

• 대한전기학회논문지:전력기술부문A
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• 제49권1호
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• pp.19-25
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• 2000

This paper describes the sheath induced voltage in underground transmission cable system which will be operated with cable cover protection unit(CCPU). Simulation was carried out to analyze the sheath induced voltage in the real cable system which was installed by 154㎸ CV cable in the case with and without CCPU. The sheath induced voltage will be also analyzed according to the change of grounding method, fault resistance and fault angle. Simulation was performed using EMTP and ATP Draw, the simulation results show whether the CCPU in necessary or not in underground transmission power cable system.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.54-60
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• 2013

There is increasing demand for practical groundings for small-area substations because of the recent revision of Korea's Electrotechnical Regulations, which necessitates the method of evaluating their safety. This paper proposes a practical mesh grounding system for 22.9kV substations and studies how to evaluate its safety. The proposed grounding system is proved to obey the safety criteria of ANSI/IEEE Std. 80 via ANSI/IEEE Std. 80 method and computer simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.196-197
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• 2006

An effective method is described for monitoring the ground impedance of intelligent building and power system. Most of grounding system of buildings are interconnected to extensive grounding network of power line, signal and control line, telecommunication line, and etc. Therefore, the residual voltages of power frequency and its harmonics may have an significant influence on the accurate measurement of ground impedance. For eliminating the influence of residual voltage, we developed a test power source for generating the 110[Hz] square wave and used digital filtering method in this research.

• 조명전기설비학회논문지
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• 제21권1호
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• pp.35-41
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• 2007

최근 고품질의 정보통신서비스와 안정한 전력공급에 대한 사회적 요구가 증가하고 있다. 본 연구에서는 뇌서지로부터 정보통신설비를 효과적으로 보호하는 대책을 제안하기 위해서 실규모 실험회로를 적용하여 여러 가지 설치조건에 따른 서지보호기의 보호효과를 실험적으로 조사하였다. 그 결과 전원계통의 접지방식, 분기회로의 수, 접지선의 배선방법 등에 따라 서지보호기의 보호효과는 크게 다른 것으로 밝혀졌다. 정보화 기기용 서지보호기를 설치하는 경우, 전원선과 통신선을 포함하는 공통접지방식과 접지선을 전원선과 일괄하여 금속관 내에 배선하는 것이 서지보호기의 서지차단성능의 향상에 가장 효과적이었다.