• Title, Summary, Keyword: Grounding point

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Grounding Characteristics Analysis of the Rod-Type Grounding Electrodes used for Electric Distribution Systems (배전계통에 사용되는 봉형 접지전극의 접지 특성 분석)

  • Kim, Kyung-Chul;Jung, Ji-Won
    • 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.

A Study on Lightning Overvoltage Characteristics of Grounding Systems in Underground Distribution Power Cables

  • Jung, Chae-Kyun;Jung, Yeon-Ha;Kang, Ji-Won
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.628-634
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    • 2014
  • This paper investigates the transient characteristics of grounding systems used in under-ground distribution power cables. Recently, two kinds of grounding system are used for underground distribution cables in Korea. The first one is conventional multi-point grounding system, the other is newly proposed non-bundled common grounding system. The non-bundled common grounding system has an advantage the decreasing the power loss due to decrease of the shield circulation current. In this paper, the lightning overvoltage induced in neutral wire (in case of non-bundled common grounding system, overvoltage between opened neural wires and grounding in each phase) of these two kinds of grounding systems are estimated and compared by field tests and EMTP simulations. The EMTP simulation methods are firstly verified by comparison of measurement and simulation. Finally, the insulation level against lightning is expected by EMTP simulation results using verified model.

The transient grounding impedance measurment of large grid grounding electrodes (대규모 그리드 접지전극의 과도접지임피던스의 측정)

  • Jeon, Byung-Wook;Lee, Su-Bong;Li, Feng;Lee, Seung-Ju;Jung, Dong-Cheol;Lee, Bok-Hee
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.69-72
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    • 2008
  • This paper presents the transient and conventional grounding impedance behaviors of large grid grounding system associated with the injection point of impulse current The measurement methods consider two possible errors in the grounding-system impedances: (1) ground mutual resistance due to current flow through ground from the ground electrode to be measured to the current auxiliary, (2) ac mutual coupling between the current test lead and the potential test lead The test circuit was set to reduce the error factors. The transient grounding impedance depends on the rise time and injection point of impulse current It is effective that grounding conductor is connected to the center of the large grid grounding system.

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Grounding Impedance Behaviors Associated with the Current Injection Point and the Length of Counterpoise (매설지선의 길이와 전류인가점에 따른 접지임피던스특성)

  • Li, Feng;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.6
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    • pp.66-71
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    • 2009
  • This paper presents the grounding impedance behaviors of counterpoise exposed to impulse currents. The transient and conventional grounding impedances of three counterpoises having the length of 10, 30 and 50[m] were measured and analyzed as a function of the injection point of impulse currents. As a result, the trend of the conventional grounding impedances measured as a function of injection of impulse current is similar to the transient grounding impedance of counterpoise. The injection point of impulse current has great influence on the transient grounding impedance characteristics of counterpoise. The transient grounding impedance characteristics in a short time range are strongly dependent on the length of counterpoise. The transient characteristics of grounding impedance of 10[m] counterpoise subjected to the impulse current was capacitive behavior, on the other hand, those of 30[m] and 50[m] counterpoises were inductive behavior. It is found that the grounding conductor should be connected to the central point of counterpoise.

Grounding Characteristics Analysis of the Stainless-steel Plate Grounding Electrode for Distribution Poles (배전전주용 스테인리스강판 접지전극의 접지 특성분석)

  • Kim, Kyung-Chul;Lee, Kyu-Jin;Kim, Min-Sung;Jung, Ji-Won
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.8
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    • pp.94-100
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    • 2010
  • 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 stainless-steel plate grounding electrode. An equivalent transfer function model of the grounding impedance and transient grounding impedance are identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.

Engineering Practice for ESS Protection by means of One Point Grounding System (일점접지방식을 이용한 전자교환기 방호의 실제)

  • Kim, Soo-Hyung;Seo, Jung-Uck
    • Proceedings of the KIEE Conference
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    • pp.502-505
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    • 1988
  • This paper is to demonstrate the effectiveness of one point grounding in support of ESS protection. One point grounding provides for the dispatching of excess energy for protection of switching equipment and personnel from lightning discharge hazards and for a natural sink for noise from atmospheric lightning and power transients. In most ESS installations there are a number of different items that must be maintained at a common ground potential for safety, fault protection or noise reduction. The items typically consist of power systems, heating and ventilating systems, distributing frames, repeating equipmets, switching equipments, etc. Grounding system of an ESS Office is most effective when all the ground points are connected to a single, common earth. The one point grounding prvides a common reference potential, keeping all the items of telecommunications facility free from the earth current and voltage hazards.

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Impulse Response Characteristics of the Grounding Systems with respect to the Common-Connection Position in Power Utility System (수변전설비에서 접지시스템의 공결점의 위치에 따른 임펄스 응답특성)

  • Lee, B.H.;Eom, J.H.;Kim, S.W.;Shim, P.S.;Lee, S.C.
    • Proceedings of the KIEE Conference
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    • pp.2149-2151
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    • 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.

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Transient Grounding Impedance Behaviors of Deeply-driven Ground Rods According to the Injection Point of Impulse Currents (임펄스전류의 인가위치에 따른 심매실 봉상 접지전극의 과도접지임피던스 특선)

  • Lee, Su-Bong;Li, Feng;Lee, Seung-Ju;Jeon, Byung-Wook;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.10
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    • pp.62-68
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    • 2008
  • This paper presents the transient and conventional grounding impedance behaviors of deeply-driven ground rods associated with the injection point of impulse currents. The transient grounding impedance strongly depends on the length of deeply-driven ground rod and the rise time and injection point of impulse currents, and the intrinsic inductance of ground rod has a significant affect on the transient grounding impedance of grounding system in fast rise time ranges. The reduction of inductance is decisive to improve the impulse impedance behaviors of deeply-driven ground rods. It is effective that grounding conductor is connected to the top of the ground rod as short as possible.

Transient impedance characteristics of counterpoise according to the current injection position (전류인가위치에 따른 매설지선의 과도접지임피던스 특성)

  • Lee, Bok-Hee;Li, Feng;Lee, Song-Zhu;Yoo, Jae-Duk;Cho, Sung-Chul
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.328-331
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    • 2009
  • This paper presents the behaviors of transient and conventional grounding impedances of a 30m counterpoise according to the injection point of lightning impulse currents. As a result, the trend of the conventional grounding impedances measured as a function of risetime of impulse current is similar to the transient grounding impedance of counterpoise. The injection point of impulse current greatly influences on the transient grounding impedance characteristics of counterpoise. The transient grounding impedances strongly depend on the injection point and the rising time of impulse current and the soil characteristics.

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Examinations on the Reasonable Measuring Methods of the Soil Resistivity for Design of Grounding System (접지시스템의 설계를 위한 대지저항률의 합리적인 측정방법 고찰)

  • Lee, Bok-Hee;Kim, Ki-Bok;Lee, Seung-Hoon;Choi, Jong-Hyuk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.6
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    • pp.35-41
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    • 2011
  • In order to design effectively the grounding system, it is very important to determine the optimum soil resistivity at the desired location of the connection to earth. This paper deals with the reasonable methods of measuring the soil resistivity where grounding electrodes are buried. The soil resistivity at three test sites with different resistivity of soil were measured as functions of the spacing between the test probes in the Wenner's four-point method and the length of test ground rod in the three-point method. In the case of the three-point method, the length of test ground rod of 2-10[m] in length was appropriate in two-layered soil structure. In the length range of 2-10[m], the results measured by the three-point method using the test ground rod with the length corresponding to the spacing between the test probes of the Wenner's four-point method are in good agreement with the data obtained from the Wenner's four-point method.