• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.204-205
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• 2006

This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1374-1379
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• 2012

Urban rail transit tends to global grounding system in order to control ground potential rise and potential differences between electric equipments. In addition, global grounding system can discharge the large capacity surge current to the ground safely. Since some railway electric equipments are installed all section of line, the global grounding system connected with the connecting grounding wire is more effectively. However, if the fault occurred in the connecting grounding wire area, some dangerous voltage is generated. So, the installation of additional grounding rod will be required. In this study, the global grounding system is simulated using CDEGS program to analyze the divergence spacing of additional ground rod depending on dangerous electric potential characteristics. Grounding net of the each station is modelled in depending on the size of the platform, and the spacing of the connecting grounding rod are compared 50m, 100m, 250m and 400m. Simulation results considering of earth resistivity and underground condition of the connecting grounding wire, spacing of the connecting grounding rod is that less than 250m to spacing of the ground rod was appropriately confirmed.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.736-741
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• 2005

This paper presents electric characteristics analysis and safe configuration for extension power supply between existent 6.6kV ungrounded distribution system and establishment and improvement 22.9kV direct grounding distribution system. For this, we model 6.6kV ungrounded and 22.9kV direct grounding distribution system of urban underground, ground region. and rural electrical, unelectrical region using PSCAD/EMTDC and analyze voltage drop, charging current, ground and short fault through simulation. To analyze electric characteristics of extension power supply, we simulate extension power supply of overhead line of 6.6kV ungrounded system and underground line of 22.9kV direct grounding system of rural electrical region and propose operation condition for safe extension power supply through result of analysis. Characteristics of voltage drop, charging current, ground and short fault appear almost similarly with electrical characteristic of direct power supply. However, because unbalance of phases may cause relay's malfunction of ungrounded system and ground fault current of direct grounding system may demage facilities of ungrounded system, we propose safe system configuration such as impedance grounding system of neutral point.

• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.394-400
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• 2006

Since Seoulmetro built the first line of electric railway at seoul 1974, the passengers of railway have been increased rapidly, and electric railway requires more electric power for the greater capacity of transport. It is important that we prevent the accidents related with the subway, because all systems of subway are constructed in artificial underground structure. Since the previous versions of the earth system were built to meet the old standards of the electric facility for the lightning, some accidents related with the DC earth fault are causing secondary damages to the electric equipments. So, the old grounding system must be improved, and new standards of grounding system are required. We compare the grounding systems of the domestic railway corporations and the accidents that are related with the grounding systems. And we give ideas to improve the grounding systems and present standards which are suitable to electric railway.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.196-197
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• 2006

An effective method is described for monitoring the ground impedance of intelligent building and power system. Most of grounding system of buildings are interconnected to extensive grounding network of power line, signal and control line, telecommunication line, and etc. Therefore, the residual voltages of power frequency and its harmonics may have an significant influence on the accurate measurement of ground impedance. For eliminating the influence of residual voltage, we developed a test power source for generating the 110[Hz] square wave and used digital filtering method in this research.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.343-346
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• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.191-197
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• 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.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.234-237
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• 2004

Measuring ground resistance has been a popular method of evaluation of the grounding electrode performance. If some portions of grounding electrodes are lost by corrosion, aging or other reasons, consequent deteriotation of the grounding performance would be resulted. It is one of the reasons why it is required to evaluate the performance of grounding systems regularly. However, in case of the electric facilities with multi-grounded system such as power substations with multi-grounded overhead ground wires and/or distribution line neutrals, it is practically difficult to disconnect neutrals or skywires from the substation grounding mesh for the ground resistance measurement. In this paper, a method for the grounding performance measurement of multi-grounded systems, which is based on the measuring ground current distributions, has been proposed. A field test results has shown the validity of the proposed test method.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.1
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• pp.35-40
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• 2020

The purpose of this paper is to improve the grounding point measurement method for the maintenance of the earth resistance of the distribution line. This study defines the correlation among humidity of the soil, the earth resistivity and the grounding resistance. Based on the results of the study, the grounding resistance value measurement should be limited to the location where the earth resistivity change is large, and the measurement time and cost can be greatly reduced.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.234-234
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• 2004

Measuring ground resistance has been a popular method of evaluation of the grounding electrode performance. If some portions of grounding electrodes are lost by corrosion, aging or other reasons, consequent deteriotation of the grounding performance would be resulted. It is one of the reasons why it is required to evaluate the performance of grounding systems regularly. However, in case of the electric facilities with multi-grounded system such as power substations with multi-grounded overhead ground wires and/or distribution line neutrals, it is practically difficult to disconnect neutrals or skywires from the substation grounding mesh for the ground resistance measurement. In this paper, a method for the grounding performance measurement of multi-grounded systems, which is based on the measuring ground current distributions, has been proposed. A field test results has shown the validity of the proposed test method.