• Title/Summary/Keyword: Grounding point

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A Study on the Integrated Monitoring of a Leakage Current of the Grounding Wire of Neutral Point of the Low Voltage Side of Transformer (변압기 저압측 중성점 접지선의 누설전류 통합 감시에 관한 연구)

  • Hong, Soon-Seuk;Park, Joon-Yeol;Lee, Jung-Eun;Choi, Kyung-Han
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.5
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    • pp.106-113
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    • 2010
  • If leakage current is neglected, it can become a cause for disasters such as electric shock and fire, therefore a continuous monitoring is necessary. However in most cases, because management of substations is performed by unmanned systems, or walk-around inspections, continuous monitor is difficult. So when an accident occurs and the cause is not immediately resolved causing the emergency generator's OCGR getting activated by the leakage current that in turn cut off the ACB, the emergency generator may stop working. To prevent such a problem, a real-time integrated monitoring system for monitoring the leakage current returning to the grounding wire of neutral point of the low voltage side of transformer is proposed. Therefore in this paper, the effects of flow of leakage current, which is caused by insulation degradation phenomena or insulation destroy phenomena, were identified by simulation. And through cases studies; the excellence of integrated monitoring system was verified.

Improvement of the Protection Algorithm Based on Voltage Difference Method for Detecting Arcing Faults within 22.9kV Shunt Capacitor Banks (22.9kV급 병렬 커패시터 뱅크 내부의 아크 고장 판별을 위한 전압차동 보호 알고리즘의 개선 방안)

  • Lim Jung-Uk;Kwon Young-Jin;Kang Sang-Hee;Yuk Yoo-Kyoung
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.2
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    • pp.61-66
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    • 2005
  • This paper presents a refined protection algorithm of the unfused 22.9kV shunt capacitor banks in grounded wye connection to improve the existing algorithm using the voltage difference method. It is difficult to detect ground faults with arc near the input points or ground faults near the grounding point by the existing algorithm using only the voltage balanced relay. This paper shows that ground faults with arc near the input point can be detected by harmonics analysis of the differential voltage and that it has no impact of harmonics out of nonlinear loads which have the quantitative influence on capacitor banks. Thus the proposed method using harmonics analysis can be a proper detection method. In case of ground faults near the grounding point, an OVGR is being added recently and its validity is verified in this paper. The proposed method is applied to a 22.9kV example system and is verified that the proposed algorithm can detect clearly faults which are not easy to detect by the existing method.

A Study on the Transient Ground Impedance Modeling for Rod-type Grounding Electrodes by Frequency and Time Domain Characteristic Tests (주파수 및 시간영역 특성시험에 의한 봉형 접지전극의 과도 접지임피던스 모델링에 관한 연구)

  • Kim, Jong-Uk;Kim, Kyung-Chul;Shin, Pan-Seok;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.133-141
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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 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. Copper and concrete rod electrodes are the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of copper and concrete rods has been measured by frequency and time domain characteristic tests. An equivalent transfer function model of the ground impedance is identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.

Ground Impedance Characteristics Analysis of a Copper Rod-type Grounding Electrode used for Electric Distribution Systems (배전계통에 사용되는 동봉 접지전극의 접지 임피던스 특성 분석)

  • Kim, Kyung-Chul;Lee, Joo-Hong;Jin, Seong-Eun;Oh, Jung-Suk;Park, Sang-Young;Choi, Jong-Ki;Kim, You-June
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.6
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    • pp.46-51
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    • 2005
  • Grounding insures a reference potential point for electric devices and also provides a low resistance path for fault currents in the earth. The ground impedance as a function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. A cower rod electrode is the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of cower rods has been measured in frequency ranging from 60[Hz] up to 100[kHz] and an equivalent circuit model, transfer function model of the ground impedance are identified from the measured values.

Protection Effects of Surge Protective Devices According to Types of system Groundings (전원계통의 접지방식에 따른 서지보호기의 보호효과)

  • 이복희;이동문;강성만;이수봉
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.17 no.6
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    • pp.66-71
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    • 2003
  • Electronic equipments made from integrated circuits and small-sized semiconductors is protected by surge protective devices(SPDs) such as ZnO varistors, Zener diode and gas discharge tube from lightning overvoltages. However the clamping voltage of SPDs is greatly influenced by the method of installing the SPDs. In this paper, the protective effects of SPDs according to types of system groundings were experimentally investigated. The separate grounding is a particularly undesirable way to install SPDs. The effectiveness of the common grounding point for ZnO varistors is more pronounced than that for gas discharge tubes. The common grounding at the terminal of SPDs is recommended as a best method of installing SPDs.

Three-Dimensional Subsurface Resistivity Profile using Electrical Resistance Tomography for Designing Grounding Grid (접지 그리드 설계를 위한 전기 저항 단층촬영법에 기반한 지표의 3차원 저항률 분포 추정)

  • Khambampati, Anil Kumar;Kim, Kyung Youn
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.4
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    • pp.117-128
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    • 2016
  • Installation of earth grounding system is essential to ensure personnel safety and correct operation of electrical equipment. Earth parameters, especially, soil resistivity has to be determined in designing an efficient earth grounding system. The most common applied technique to measure soil resistance is Wenner four-point method. Implementation of this method is expensive, time consuming and cumbersome as large set of measurements with variable electrode spacing are required to obtain a one dimensional resistivity plot. It is advantageous to have a method which is of low cost and provides fast measurements. In this perspective, electrical resistance tomography (ERT) is applied to estimate subsurface resistivity profile. Electrical resistance tomograms characterize the soil resistivity distribution based on the measurements from electrodes placed in the region of interest. The nonlinear ill-posed inverse problem is solved using iterated Gauss-Newton method with Tikhonov regularization. Through extensive numerical simulations, it is found that ERT offers promising performance in estimating the three-dimensional soil resistivity distribution.

Optimal Ship Route Planning in Coastal Sea Considering Safety and Efficiency (안전과 효율을 고려한 연안 내 선박의 최적 항로 계획)

  • Lee, Won-Hee;Choi, Gwang-Hyeok;Ham, Seung-Ho;Kim, Tae-wan
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2019.05a
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    • pp.38-39
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    • 2019
  • Optimal route planning is the route planning to minimize voyage time or fuel consumption in a given ocean environment. Unlike the previous studies on weather routing, this study proposes an optimization method for the route planning to avoid the grounding risk in the coast. The route way-points were searched using Dijkstra algorithm, and then the optimization was performed to minimize fuel consumption by setting the optimization design parameter to the engine rpm. To set the engine rpm, a method to use the fixed rpm from the departure point to the destination point, and a method to use the rpm for each section by dividing the route were used. The ocean environmental factors considered for route planning were wind, wave, and current, and the depth information was utilized to compute grounding risk. The proposed method was applied to the ship passing between Mokpo and Jeju, and then it was confirmed that fuel consumption was reduced by comparing the optimum route and the past navigated route.

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Improvement of Digital Distance Relaying Algorithm Using Wavelet Transform in Combined Transmission Line (웨이브렛을 이용한 혼합송전선로에서의 거리계전 알고리즘 개선)

  • 정채균;김경호;하체웅;이종범;윤양웅
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.10
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    • pp.593-601
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    • 2003
  • Distance realy is tripped by the line impedance calculated at the relay point. Accordingly the accurate operation depends on the precise calculation of line impedance. Impedance can be accurately calculated in case of overhead line. However, in case of power cables or combined transmission lines, impedance can not be accurately calculated because cable systems have the sheath, grounding resistance, and sheath voltage limiters(SVLs). There are also several grounding systems in cable systems. Therefore, if there is a fault in cable systems, these terms will severely be caused much error to calculation of impedance. Accordingly the proper compensation should be developed for the correct operation of the distance relay. This paper presents the distance calculating algorithm in combined transmission line with power cable using wavelet transform. In order to achieve such purpose, judgement method to discriminate the fault section in both sections was proposed using D1 coefficient summation in db4. And also, error compensation value was proposed for correct calculation of impedance in power cables section.

The Adequacy Analysis for Installation of High Speed Grounding Switches on the Korean 765kV Single Transmission Line

  • Ahn, Sang-Pil;Kim, Chul-Hwan;Park, Nam-Ok;Ju, Hyung-Jun;Shim, Eung-Bo
    • Journal of Electrical Engineering and Technology
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    • v.1 no.4
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    • pp.427-434
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    • 2006
  • This paper analyzes arc phenomena including the secondary arc's elongation in the Korean 765kV single transmission line (79km) between Sin-Ansung S/S and Sin-Gapyeong S/S, which will be installed in Korea in June 2006. In particular, both frequency independent and frequency dependent line models are compared to make our final decisions. As well, the significant simulation results are investigated by the EMTP program. As a result, there is no need of HSGS in the Korean 765kV single transmission line from both a practical and an economical point of view.

A Study on the Analysis of Klippon Relay Malfunction in Cheju-Heanam HVDC System (제주-해남 HVDC 시스템에서 클리폰 릴레이 오동작 분석에 관한 연구)

  • Kim, Chan-Ki;Park, Jong-Kwang;Choy, Young-Do
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.173-175
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    • 2005
  • Malfunction of Klippon relay in Cheju-Haenam HVDC system has been caused by the inflow of high voltage arc. In this paper, we have studied on the theoretical examination and data analysis of Klippon relay, and the countermeasures against the problems were suggested according to their causes. Grounding problem in Klippon relay is removed by one-point earth connection and by modification of grounding circuit. The effects of over current surge was removed by attaching blocking diodes by series In Klippon relay to remove surge input in Klippon relay's mercury contact. The problem of Induced overvoltage by 86re1ay excitation coil, was removed by attaching Free-wheeling diode in parallel with the excitation coil of Lock-out relay.

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