• 조명전기설비학회논문지
• /
• 제15권2호
• /
• pp.97-104
• /
• 2001

본 논문에서는 전위강하법에 의한 접지저항 측정시 전위보조전극 위치의 영향에 대하여 기술하였다. 전위강하법에서 접지저항은 이론적으로 전위보조전극을 피측정 접지전극과 전류보조전극이 이루는 일직선상에 위치시킬때 61.8[%]법칙을 적용하여 측정한다. 하지만 측정현장의 사정상 전위보조전극의 위치를 피측정 접지전극과 전류 보조전극이 이루는 일직선과 어느 정도의 각도를 가지도록 시설하여 접지저항을 측정하게 될 경우에 측정오차가 발생하게 되고 보정이 필요하다. 본 연구에서의 측정대상 전극은 길이 2.4 [m]의 봉형 접지전극으로 하였으며, 피측정 접지전극, 전위보조전극, 전류보조전극이 일직선상에 놓이지 않은 상태에서 접지저항을 측정하면 측정값은 항상 (-)의 오차를 나타내었고, 이들 전극이 이루는 각도가 증가함에 따라 측정 오차도 증가하였다.

• 조명전기설비학회논문지
• /
• 제24권6호
• /
• pp.60-66
• /
• 2010

국내 외 메쉬접지극은 격자형태의 등간격 접지Grid로 설계하고 있다. 격자형 접지Grid의 경우 구석의 접촉전압이 중심 부분에 비해 높아지는 문제점이 있다. 이러한 문제점을 극복하기 위해 사선형태의 접지 Grid를 사용하면 메쉬전압이 발생하는 구석부분의 면적이 감소함으로써 메쉬전압이 감소한다. 따라서 본 논문에서는 기존의 격자형태의 접지Grid의 형태와 다르게 사선형태의 접지Grid를 제안하며, 격자형태의 접지Grid와 사선형태의 접지Grid로 설계된 메쉬접지극에 동일한 접지설계제원을 적용하고 메쉬전압, GPR, 접지저항, 접지도체의 총길이를 비교 검토하여 사선형태 접지Grid의 우수성을 검증하였다.

• 조명전기설비학회논문지
• /
• 제25권4호
• /
• pp.38-44
• /
• 2011

Grounding electrodes with higher burial depths are evaluated to have better performance, due to the domestic practice that puts the grounding resistance as the standard of performance evaluation, while grounding resistance decreases as the burial depth increases. However, The dangerous voltage is necessary for the analysis. Because the performance evaluation of grounding electrodes should include not only grounding resistance but also the dangerous voltage(mesh voltage and step voltage). So in this paper, The dangerous voltages of mesh grounding and rod grounding were analyzed for using computer simulation and miniature grounding model.

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

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1360-1361
• /
• 2008

This paper presents the surface potential rise distribution near grounding electrodes produced by ground fault currents. The small-scale model with the foundation pedestal in hemispherical tank was used to simulate the ground fault condition of the electrical installations for street lamps. When entering the fault current through the test ground electrode, surface potential rise, potential gradient, touch and step voltages for different grounding electrode shapes were measured, and the results obtained were discussed.

• 전력전자학회논문지
• /
• 제26권2호
• /
• pp.90-95
• /
• 2021

In contrast to AC grounding systems, the ground electrode in DC systems continuously maintains positive or negative polarity. Ground electrodes with (+) polarity proceeds by oxidation reaction. Thus, the DC current should flow opposite to the polarity of the leakage current flowing through the (+) ground electrode by using a compensation electrode, and the current flowing through the (+) ground electrode can be 0A. However, according to protecting the (+) ground electrode, the compensation electrode corrodes and gets damaged. Thus, the (+) ground electrode must be protected from corrosion, and the service life of the compensation electrode must be extended. As an alternative, the average value of the current flowing through the compensation electrode should be equal with the value of the leakage current flowing through the (+) ground electrode by using the square waveform. Throughout the experiment, the degree of corrosion on the compensation electrode is analyzed by the frequency of the compensation electrode for a certain time. In the experiment, the frequencies of the square waveform are considered for 0.1, 1, 10, 20, 50, 100 Hz, and 1 kHz. Through experiments and analysis, the optimal frequency for reducing the electrolytic damage of the (+) electrode and compensation electrode in an LVDC grounding environment is determined.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
• /
• pp.361-364
• /
• 2008

This paper deals with assessment of electrical safety for grounding system of buildings by investigation on the spot at construction site. The investigation was carried out for grounding method, grounding type, shape of grounding electrode, grounding for lightning protection system, continuity of steelwork in reinforced concrete structure and so on. The investigation on the spot was performed by researcher, engineer with over fifteen years of industry experience all over the country. As a result of investigation on the spot to 13 buildings, common grounding method was dominant. A new grounding system based on international standards includes unity grounding system, structure grounding utilizing steel reinforced concrete, equipotential bonding. use of surge protective device.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2009년도 추계학술대회 논문집
• /
• pp.47-50
• /
• 2009

When the lightning currents flow through the ground electrode, the grounding system should be evaluated by the grounding impedance rather than the ground resistance because a grounding system shows the transient impedance characteristic by the inductance of the ground electrode and the capacitance of the soil. The ratio of the peak values of electric potential and currents is the conventional impedance that shows the transient characteristic about impulse currents of the grounding system in a roundabout way. The grounding system having low conventional impedance is a fine grounding system with low electric potential when the lightning currents flow. In this paper the conventional impedance of the counterpoise is calculated by using the distributed parameter circuit model and embodied the distributed parameter circuit model by using the EMTP program The adequacy of the distributed parameter model is examined by comparing the simulated and the measured results. The conventional impedance of the counterpoise is analyzed for first short stroke and subsequent short stroke currents.

• 조명전기설비학회논문지
• /
• 제25권6호
• /
• pp.68-74
• /
• 2011

The touch or step voltages which exist in the vicinity of a grounding electrode are closely related to the earth structure and resistivity and the ground current. The grounding design approach is required to determine the grounding electrode location where the hazardous voltages are minimized. In this paper, in order to propose a method of mitigating the electric shock hazards caused by the ground surface potential rise in the vicinity of a counterpoise, the hazards relevant to touch voltage were evaluated as a function of the soil resistivity ratio $\rho_2/\rho_1$ for several practical values of two-layer earth structures. The touch voltage and current on the ground surface just above the test electrode are calculated with CDEGS program. As a consequence, it was found that burying a grounding electrode in the soil with low resistivity is effective to reduce the electric shock hazards. In the case that the bottom layer soil where a counterpoise is buried has lower resistivity than the upper layer soil, when the upper layer soil resistivity is increased, the surface potential is slightly raised, but the current through the human body is reduced with increasing the upper layer soil resistivity because of the greater contact resistance between the earth surface and the feet. The electric shock hazard in the vicinity of grounding electrodes is closely related to soil structure and resistivity and are reduced with increasing the ration of the upper layer resistivity to the bottom layer resistivity in two-layer soil.

• 한국전기전자재료학회논문지
• /
• 제29권5호
• /
• pp.303-306
• /
• 2016

Floating PV system is installed on the water such as artificial lake, reservoir, river for the purposes of zero energy town and/or large scale of PV station. There are electrical gains from cooling effect by water and reflection of water surface. Particularly, floating PV power station with high efficiency solar cell modules receives a lot of attention recently. Floating PV system is installed on the water, which means grounding method to the frame of solar cell and electrical box such as connector band and distribution panelboard should be applied in different way from grounding method of PV system on land. The grounding resistance should be 10[${\Omega}$] in case the voltage is over 400[V] in accordance with Korean Standard. The applicable parameters are the resistivity of water in various circumstances, depth of water, and length of electrode in order to meet 10[${\Omega}$] of grounding resistance. We calculated appropriate length of the electrode on the basis of theoretical equation of grounding resistance and analyzed the relation between each parameters through MATLAB simulation. This paper explains grounding system of floating PV power station and presents considerations on grounding design according to the resistivity of water.