• KIEE International Transactions on Electrophysics and Applications
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• 제4C권5호
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• pp.207-214
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• 2004

This paper presents the characteristics of transient and effective impulse impedances for deeply driven grounding electrodes used in soil with high resistivity or in downtown areas. The laboratory test associated with the time domain performance of grounding piles subjected to a lightning stroke current has been carried out using an actual-sized model grounding system. The ground impedances of the deeply driven ground rods and grounding pile under impulse currents showed inductive characteristics, and the effective impulse ground impedance owing to the inductive component is higher than the power frequency ground impedance. Both power frequency ground impedance and effective impulse ground impedance decrease upon increasing the length of the model grounding electrodes. Furthermore, the effective impulse ground impedances of the deeply driven grounding electrodes are significantly amplified in impulse currents with a rapid rise time. The reduction of the power frequency ground impedance is decisive to improve the impulse impedance characteristics of grounding systems.

• 조명전기설비학회논문지
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• 제24권12호
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• pp.208-213
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• 2010

This paper deal with an analysis of the ground surface potential profiles using a hemispherical scaled-model. Because it is very difficult to draw valid conclusions concerning a general grounding problem from actual field data, scale model tests can be used to determine the ground surface potential profile around the grounding electrodes according to the configuration of grounding electrodes. In this work, a hemispherical vessel with a diameter of 1,100 [mm] was employed to simulate uniform soil and CDEGS program was employed to compare the measured and simulated results. As a result, the ground surface potential around the grounding electrode was significantly raised and the ground surface potential at the just upper point of ground electrode particularly was higher than other points. The ground surface potential of counterpoise was higher than other grounding electrodes such as mesh and grounding rods and the ground surface potential strongly depends on the frequency responses of grounding electrodes. Also the results measured with the small-sized model were in reasonably agreement with the data obtained from simulation.

• 전기학회논문지
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• 제62권9호
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• pp.1308-1312
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• 2013

In this paper, carried out for optimal ground system for ensuring safety for electricity used to power equipment in the 20 kHz frequency. Now the grounding system of the mesh electrode, electrode rods are installed for power plant safety and protection against electric shock. However, the electrical equipment grounding system in the 20 kHz were considering the increasing grounding impedance due to the high frequency and the magnetic shielding. But until now, there has been little research on the grounding system. To solve this problem, In this paper was proposed optimal grounding system due to the experiment using a mesh electrode, rod electrode, aluminum plate electrodes. Measurement results, grounding resistance was depending on the material of the electrode grounding resistance. In addition, the leakage current (induced) appeared to be affected depending on the type of electrode.

• 조명전기설비학회논문지
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• 제23권1호
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• pp.36-40
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• 2009

콘크리트 전주는 배전선로 지지물로서 널리 사용되고 있다. 전주의 접지저항을 규정치 이내로 유지하기 위하여 동피복 접지봉을 포함한 여러 종류의 접지전극들이 사용되어 왔다. 전주 내부에는 철근이 들어있기 때문에 지중에 매설되는 전주 하단은 어느 정도 구조체접지극으로서 작용을 하게 된다. 본 논문에서는 전주 접지선으로 시험전류를 주입하면서 주입되는 전류와 금속 접지극으로 분류되는 전류를 각각 측정하였다. 이로써 전주 구조체로 분류되는 전류의 간접측정이 가능하였다. 측정결과에 근거하여 금속 접지극의 접지저항과 전주 구조체로 분류되는 전류크기 간의 상관관계를 분석하였다.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.107-112
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• 2011

Multiple ground rods are commonly used to obtain the low ground impedance, but they will not reduce the ground impedance unless the spacings between the ground rods are sufficient. This paper presents the experimental results of frequency-dependent resultant ground impedance of two ground rods in parallel. The resultant ground impedance of two ground rods in parallel were measured as functions of the spacing and length of ground rods and the frequency of test currents and were discussed based on the potential interferences. As a consequence, the frequency-dependent ground impedance of single ground rod and two combined ground rods give capacitive. It was found that the effect of potential interference on the ground impedance is directly associated with the frequency-dependent ground impedance and is strong in low frequency. Also, in order to reduce the increasing rate of resultant ground impedance of two ground rods due to potential interference to within 10(%), two ground rods in parallel will be placed over one rod length apart.

• 조명전기설비학회논문지
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• 제24권5호
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• pp.37-43
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• 2010

넓은 범위의 주파수 스펙트럼을 포함하고 있는 낙뢰나 전력변환 기기들을 고려할 때 접지시스템의 성능은 접지임피던스에 의해 평가되어야 한다. 본 논문은 실규모의 수직 접지전극과 매설지선에 대한 접지임피던스의 주파수 의존성에 대한 측정결과를 나타낸다. 수직 접지전극과 매설지선의 접지임피던스는 접지전극의 길이와 토양의 대지저항률에 따라 용량성 또는 유도성 특성을 나타내었으며, 단순히 접지저항을 낮추기 위해 접지전극의 길이를 증가시키는 것은 비효율적이며 접지임피던스를 고려한 접지설계가 요구된다. 또한 매설지선의 접지임피던스를 저감시키기 위해 접지도선은 매설지선의 중앙에 접속되어야 하며, 봉상 접지전극을 매설지선과 병렬로 설치하는 것이 접지임피던스의 저감에 효과적인 것으로 나타났다.

• 조명전기설비학회논문지
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• 제22권2호
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• pp.57-62
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• 2008

본 논문에서는 전위상승에 대한 개별 접지전극과 연접된 접지전극의 비교를 다루었으며, 시험전류가 접지전극에 흐를 때 실시간으로 접지방식에 대한 전위상승이 측정 및 분석되었다. 접지시스템의 전위상승을 분석하기 위해 반구형 수조실험장치가 사용되었고, 이를 이용하여 접지방식 및 거리에 따라 전위상승이 측정되었다. 실험장치는 반구형 수조, 전원공급장치, 이송형 전위계측장치, 시험 접지전극으로 구성되었고 전위계측장치의 프로브가 수평방향으로 이송함에 따라 전위상승이 측정되었고, 접지전극으로는 80 : 1 축척의 봉형 접지전극을 사용하였다. 개별 접지전극의 전위상승이 연접된 접지전극보다 높게 나타났으며 전위분포는 접지전극으로부터의 거리에 의존하는 특성을 나타내었다.

• Corrosion Science and Technology
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• 제17권5호
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• pp.211-217
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• 2018

Natural degradation of grounding-electrode in soil environment should be monitored for several decades to predict the lifetime of the grounding electrode for efficient application and management. However, long-term studies for such electrodes have many practical limitations. The conventional accelerated corrosion test is unsuitable for such studies because simulated soil corrosion process cannot represent the actual soil environment. A preliminary experiment of accelerated corrosion test was conducted using existing test standards. The accelerated corrosion test that reflects the actual soil environment has been developed to evaluate corrosion performances of grounding-electrodes in a short period. Several test conditions with different chamber temperatures and salt spray were used to imitate actual field conditions based on ASTM B162, ASTM B117, and ISO 14993 standards. Accelerated degradation specimens of copper-bonded electrodes were made by the facile method and their corrosion performances were investigated. Their corrosion rates were calculated to $0.042{\mu}m/day$, $0.316{\mu}m/day$, and $0.11{\mu}m/day$, respectively. These results indicate that accelerated deterioration of grounding materials can be determined in a short period by using cyclic test condition with salt spray temperature of $50^{\circ}C$.

• 조명전기설비학회논문지
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• 제24권2호
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• pp.9-15
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• 2010

접지시스템은 전기설비의 기준 전위점을 확보할 뿐만 아니라 대지에 낮은 저항으로 고장전류나 과도전류를 흐르게 한다. 주파수에 대한 함수로 접지 임피던스는 고장이나 과도전류가 넓은 범위의 주파수 성분을 포함하기 때문에 접지성능을 평가하는데 필요하다. 콘크리트봉은 배전계통에서 널리 쓰이는 접지전극중의 하나이다. 본 논문에서는 콘크리트봉의 접지 임피던스를 주파수 60[Hz]에서 100[kHz] 범위까지 측정하여 등가 접지임피던스 모델을 구하였다. 뇌서지가 유입되었을 때 EDSA 프로그램으로 과도접지임피던스의 수치와 파형을 시뮬레이션 하였다.

• 조명전기설비학회논문지
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• 제23권8호
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• pp.26-32
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• 2009

접지시스템은 전기설비의 기준 전위점을 확보할 뿐만 아니라 대지에 낮은 저항으로 고장전류나 과도전류를 흐르게 한다. 주파수에 대한 함수로 접지 임피던스는 고장이나 과도전류가 넓은 범위의 주파수 성분을 포함하기 때문에 접지성능을 평가하는데 필요하다. 동봉은 배전계통에서 가장 많이 쓰이는 접지전극이다. 본 논문에서는 동봉의 접지 임피던스를 주파수 60[Hz] 에서 100[kHz] 범위까지 측정하여 등가 접지임피던스 모델을 구하였다. 뇌격서지가 유입되었을 때 EDSA 프로그램으로 과도접지임피던스의 수치와 파형을 시뮬레이션 하였다.