• Title/Summary/Keyword: Grounding Impedance

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Frequency-Dependant Grounding Impedances According to the Length of Grounding Electrode and the Joint Position of Ground Conductors (접지전극의 길이 및 접지도선의 접속위치에 따른 접지임피던스의 주파수의존성)

  • Choi, Jong-Hyuk;Choi, Young-Chul;Cho, Sung-Chul;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.5
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    • pp.37-43
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    • 2010
  • When lightning surges with wide frequency spectrum and power converting devices are considered, it is desirable to evaluate grounding system performance by grounding impedances. This paper presents the measured results for frequency-dependent grounding impedance for the vertical grounding electrode and counterpoise on a scale of full size. Grounding impedances of vertical grounding electrodes and counterpoises give capacitive or inductive behaviors according to the length of grounding electrodes and soil resistivity. It is inefficient to extend the length of the grounding electrode in order to decrease the ground resistance, and when designing the grounding system, the consideration of the grounding impedance should be desirable. In order to reduce the grounding impedance of counterpoise, the grounding conductors are jointed at the center of counterpoises. It is effective to reduce the grounding impedance by connecting ground rods to counterpoises in parallel.

Transient Grounding Impedance Characteristics of a Concrete Rod-type Grounding Electrode used for Electric Distribution Systems (배전계통에 사용되는 콘크리트봉 접지전극의 과도 접지임피던스 특성)

  • Kim, Kyung-Chul;Kim, Jong-Uk;Lee, Kyu-Jin;Choi, Jong-Ki;Choi, Sun-Kyu;Kim, Dong-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.2
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    • pp.9-15
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    • 2010
  • Grounding insures a reference potential point for electric devices and also provides a law resistance path for fault or transient currents in the earth. The grounding impedance as a function of frequency is necessary for determining its performance since fault or transient currents could contain a wide range of frequencies. A concrete rod electrode is one of the commonly used grounding electrodes in electric distribution systems. In this paper, the grounding impedance of concrete rods has been measured in frequency raging from 60[Hz] up to 100[kHz] and an equivalent model of the grounding impedance is identified from the measured values. The grounding impedance under study when a typical lightning surge is injected into the grounding system was simulated numerically and graphically through the use of the EDSA software program.

Transient Impedance Characteristics of Grounding Rods (봉상접지극의 과도임피던스 특성)

  • 김일권;김점식;송재용;길경석
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2000.10a
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    • pp.568-572
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    • 2000
  • This paper describes the experimental results of a transient impedance characteristics of grounding rods to a square pulse and standard lightning impulse current. The test were performed on single grounding rod($\phi$ 10mm, 1m) and triple-grounding rods( $\phi$ 10mm, 1m) of equilateral triangles with 5m spacing. For measurements of transient impedance, a pulse generator which can produce square wave of 30ns rise time and 20U Pulse duration was designed and fabricated. In the experiment, transient impedance of the grounding systems have been investigated from the recorded potential and current waveforms. The results showed that the value of the transient impedance is quite higher than the stationary resistance, and provide useful information for the value of a grounding system considered transient characteristics under a high frequency condition such as lightning stokes and ground-fault.

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Ground Impedance and Frequency Response Characteristics of Large-scale Ground Rods (대형 봉상 접지전극의 접지임피던스와 주파수 응답특성)

  • Lee, Bok-Hee;Eom, Ju-Hong;Kim, Tai-Doo;Chung, Dong-Chul;Kil, Hyeong-Joon
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1791-1793
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    • 2003
  • In order to analyze the dynamic characteristics of ground impedance in large grounding system for lightning and surge protections, a novel method for measuring the ground impedance as a function of frequency was proposed. The experiments were carried out in the grounding system composed of ground rods and mesh grids. The test current was injected by the variable frequency inverter whose frequency is linearly controlled in the range of $5{\sim}500$kHz. The ground impedance and frequency response of the grounding system were mainly caused by the inductive current flowing through grounding conductors over the frequency of 2002. In the combined grounding system of rods and mesh grids, inductive component of ground impedance was significantly decreased. It was fumed out that the grounding system is effective for the surge protection.

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Transient Grounding Impedance Characteristics of a Copper Rod-type Grounding Electrode used for Electric Distribution Systems Using EDSA Program (EDSA 프로그램을 이용한 배전계통에 사용되는 동봉 접지전극의 과도 접지임피던스 특성)

  • Kim, Kyung-Chul;Oh, Kyung-Hoon;Kim, Min-Sung;Choi, Jong-Kee;Kim, Dong-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.8
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    • pp.26-32
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    • 2009
  • Grounding insures a reference potential point for electric devices and also provides a law resistance path for fault or transient currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault or transient currents could contain a wide range of frequencies. A copper rod electrode is the most commonly used grounding electrode in electric distribution systems. In this paper, the grounding impedance of copper rods has been measured in frequency raging from 60[Hz] up to 100 [kHz] and an equivalent model of the grounding impedance is identified from the measured values. The grounding impedance under study when a typical lightning surge is injected into the grounding system was simulated numerically and graphically through the use of the EDSA software program.

Transient Impedance Characteristics of Grounding Rods (봉상접지극의 과도임피던스 특성)

  • 김일권;송재용;길경석;권장우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.1
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    • pp.133-143
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    • 2001
  • This paper describes the correlation of the transient impedance and its parameters with the stationary resistance of a grounding system to a square pulse current and a lightning impulse current. In the experiment, the grounding system consists of a single grounding rod$(\Psi10[mm], 1[m])$and/or a triple-grounding rods of equilateral triangles with 5[m] spacing for operation. To analyze the transient impedance characteristics of the grounding system, a pulse generator which can produce square wave of a 30[ns] rise-time and a $20[\mus] $pulse duration is designed and fabricated. The injected content in the grounding system and the developed potential were recorded, and the time variation of the transient impedance were calculated as the ratio of the potential rising to the injected current at each time. The transient impedance and the effective surge impedance Z3 which defines economic protection level in power system were quite higher than the stationary resistance. The grounding impedance is decreased by the application of the triple-rods grounding system, and its effect is decreased as the frequency of the current is increased due to the inductance of the grounding leads.

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Transient Impedance of the Ground Grid and Deeply-driven Ground Rod (그리드접지와 심매설 접지전극의 과도임피던스)

  • Lee, Bok-Hee;Lee, Su-Bong;Lee, Tae-Hyung;Jung, Hyun-Uk;Jeong, Dong-Cheol;Gil, Hyoung-Jun
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.05a
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    • pp.240-243
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    • 2005
  • This paper presents the transient behaviors of grounding system impedance against lighting impulse currents. The dynamic characteristics of the deeply driven ground rod and grounding grid subjected to the impulse current with various rise time were investigated. It was found that 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 ground impedance of grounding system in the short time domain.

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Transient Ground Impedances According to Shapes of Grounding Electrodes (접지전극의 형상에 따른 과도접지임피던스)

  • Lee, Bok-Hee;Lee, Su-Bong;Lee, Tae-Hyung;Jung, Hyun-Uk;Jeong, Dong-Cheol
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.1
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    • pp.65-70
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    • 2006
  • This paper presents the transient behaviors of grounding system impedance against lightning impulse currents. The dynamic characteristics of the deeply driven ground rod and grounding grid subjected to the impulse current were investigated. 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 ground impedance of grounding system Also, the deeply-driven ground rod was effective to reduce the transient ground impedance in time domain of miceroseconds.

Analysis for the conventional impedance of counterpoise using EMTP (EMTP를 이용한 매설지선의 규약접지임피던스 해석)

  • Kim, Jong-Ho;Joe, Jeong-Hyeon;Beak, Young-Hwan;Lee, Gang-Su;Lee, Bok-Hee
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2009.10a
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    • pp.47-50
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    • 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.

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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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    • 2008.10a
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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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