• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2009년도 추계학술대회 논문집
• /
• pp.343-346
• /
• 2009

The grounding system of low voltage power systems is TT grounding system in Korea. In order to follow the international standard, TN grounding system is adopted. However, the performance of grounding systems has not been evaluated. This paper deals with the experimental results of protection ability of grounding system when lightning surge invades to the neutral line of low voltage power system. As a result, the TT grounding system is most frail for the lightning surge and it does not protect the electrical devices. On the other hand, the TN grounding system perfectly protects the electrical equipment and prevents the electric shock for human through the equipotential bonding. In case of TN system with supplement grounding, it is very important to lower the supplement grounding resistance to protect the electrical equipment and electric shock for human.

• 전기학회논문지
• /
• 제57권2호
• /
• pp.191-197
• /
• 2008

This paper describes the effect of transient state in underground transmission and distribution lines installed together in the same tunnel. Two systems installed in the same tunnel are operated by the common grounding. This paper analyzed that how much one of the two kinds of systems influences the other systems during the transient state by EMTP/ATPDraw. Single line-to-ground fault and lightning surge were selected in transient state condition. These cases were simulated variously according to the variation of common grounding magnitude, fault location and lightning surge magnitude. It is evaluated that the analyzed results will be used for establishment and operating materials of common grounding in the same tunnel.

• 조명전기설비학회논문지
• /
• 제24권3호
• /
• pp.39-45
• /
• 2010

This paper deals with investigation on the spot for grounding systems of buildings based on international standards at construction sites. The investigation was carried out for grounding method, grounding type, shape of grounding electrode, grounding for a lightning protection system, continuity of steelwork in reinforced concrete structures, etc. The investigation on the spot was performed by a researcher and engineer with over fifteen years of industry experience all over the country. As a result of the investigation on the spot in 13 buildings, common grounding and structure grounding methods were dominant. The safety improvement methods include installation of equipotential bonding conductors for the connection to the main earthing terminal, equipotential bonding conductors for supplementary bonding, use of Surge Protective Devices (SPD), and safe connections between earthing conductors and the rebar.

• 조명전기설비학회논문지
• /
• 제25권4호
• /
• pp.97-103
• /
• 2011

The most important object of grounding systems is to protect human being from electric shock. Touch and step voltages are measured to evaluate the performances of grounding systems. Dangerous voltages have been largely studied by the power frequency fault currents, on the other hand, the ground current containing the high frequency components and surge currents haven't been considered. Many attempts about the grounding impedances reported in these days show that the performance of the grounding systems in high frequency range is very different with the ground resistance. It is necessary to analyze the dangerous voltages formed by the ground currents containing high frequency components. In this paper, the ground surface potential rises near the vertical and horizontal grounding electrodes are measured at the frequency of 100[Hz], 30[kHz], and 100[kHz]. Dangerous voltages are investigated with the frequency-dependent grounding impedance. As a result, the ground surface potential rise is increased as the grounding impedance increases. Touch and step voltages near the grounding electrode whose impedance increases with the frequency are sharply raised.

• 조명전기설비학회논문지
• /
• 제23권9호
• /
• pp.40-46
• /
• 2009

비록 접지저항은 접지전극의 접지성능을 좌우하는 지수이기는 하지만, 과도상태에서는 접지 성능을 반영하지 못한다. 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 MATLAB 프로그램으로 과도접지임피던스의 수치와 파형을 시뮬레이션하였다.

• 조명전기설비학회논문지
• /
• 제21권4호
• /
• pp.73-79
• /
• 2007

In order to analyze the potential rise of grounding systems installed in buildings, a hemispherical grounding simulation system was studied. Potential rise was measured and analyzed regarding the shape and distance of the grounding electrodes by using this system. The system was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The potential rise was measured in real time by the horizontal moving probe of be potentiometer. The test grounding electrodes were fabricated through reducing the grounding electrode installed in real buildings such as the ground rod, grounding grid and so on. The potential rise was displayed in a two-dimensional profile and was analyzed regarding the shapes of the ground electrodes. The potential rise of the grounding grid combined with a ground rod was the lowest of every grounding electrode tested. The proposed results can be applicable to evaluating ground potential rise in grounding systems, and the analytical data can be used to stabilize the electrical installations and prevent electrical disasters.

• 한국조명전기설비학회지:조명전기설비
• /
• 제6권5호
• /
• pp.45-49
• /
• 1992

The transient characteristics of grounding systems are very important in the insulation design of electrical installations and depend on the shape and size of electrodes, soil resistivity and the magnitude and wave of the injection current. This paper establishes an algorithm to compute the surge impedance of two or more grounding systems using the Laplace Transformation technique and deals with the analysis of the transient characteristics on grounding systems.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.740-741
• /
• 2007

This paper analyses the transient state of underground distribution system against single line to ground fault in underground transmission systems, when underground transmission systems and distribution systems are made of common grounding. Underground transmission systems and distribution systems are modeled by EMTP/ATPDraw. Simulation is carried out considering variation of parameters such as value of common grounding, balance load and unbalance load.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.1482-1504
• /
• 2007

철도시스템은 열차견인을 위한 고전압시스템, 열차제어를 위한 저전압시스템을 사용하며, 철도를 구성하는 시스템이 지형적으로 광범위하게 분포되어 있다. 철도시스템에서 전차선의 지락에 의한 과대한 고장전류, 낙뢰 등에 의한 이상 고전압이 발생되어 사람의 사상 및 기기의 고장이 발생할 수 있는데, 지락에 의한 고장전류, 낙뢰에 의한 고전압으로부터 기기를 보호하기 위해서 접지를 설치한다. 각 시스템에 대한 단독접지를 하는 경우에는 기기 상호가 폐회로가 형성되어 이상전류가 흐르게 되어 기기를 정상적으로 작동시키지 못하는 경우가 있다. 따라서 이러한 해결책으로 등전위 접지시스템을 채용한다. 이러한 등전위 접지시스템은 매우 낮은 접지저항을 확보하여야 한다. 본 논문에서는 철도시스템에서 기존의 단독접지시스템에서 현재의 공통접지시스템으로의 변화 및 두 시스템의 시뮬레이션 비교분석과 앞으로의 새로운 접지시스템에 대한 방향에 대해 제시하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 E
• /
• pp.2149-2151
• /
• 1999

This paper describes the impulse response characteristics of the grounding systems in power utility system. Several regulations regarding to electric power equipments, services and managements require that the groundings of class 1 ($E_1$) and class 2 ($E_2$) must be connected at the common point in grounding systems. In addition, the grounding for arrester ($E_{LA}$), which belongs to the grounding of class 1, should be connected at the same point. However, there is no method and position of common-connection at anywhere. In this work, when the impulse current was injected through the grounding conductor for arrester, the investigations measuring and analyzing potential rises induced at the common connection point and other grounding conductors were conducted. The experiments were carried out in the conditions of the grounding conductor of 25m long and the near or remote common connection from ground electrode. The lightning impulse current was applied so as to simulate the on-set of arrester due to lightning and/or switching surges.