• 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 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.

• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.85-89
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• 2010

During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multi-grounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A effect by grounding resistance of poles of ground fault current in the 22.9[kV] multi-ground distribution system. by field tests.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1738-1740
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• 2003

This paper deals with the characteristic analysis of multi-grounding system. In order to assess the effectiveness of bonding two grounding systems, the scale model grounding simulation system and grid grounding conductors which were downsized as a scale factor of 100:1 were designed and fabricated. A profile of GPR(Grounding Potential Rise) of each case was measured. Also the measured results were compared with the analysis results.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.47-50
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• 2001

Presently the Korean grounding system uses TN system, multi-grounding method with TT independent grounding method. Nevertheless TN system can't exist with TT system in the technological terms. If they coexist, it causes ground-fault circuit not to operate, and brings about different electrical potential rise by customer system. It brings about serious problems for safety. This paper aims for improving method of grounding system based on the technical analysis on instances in foreign countries and Korea. Almost standards and construction manner were apt to be internationalized after WTO/TBT agreement was concluded. The internal grounding systems should meet the international criteria and reliability for safety, and be provided with technologically impeccable standards.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.10
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• pp.489-492
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• 2001

The connection method of CCPU has been changed from connection between sheath and grounding to connection between sheaths without grounding since 1997. In domestic, there is so many cases that cables circuits were installed before 1997, added in same route after that, operated as multi-connecting systems of CCPU in same route. This paper examine the problem of multi-connecting system by EMTP simulation, and presents methods to improve the system characteristics.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1188-1191
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• 1998

Detailed estimation of subsurface resistivity distribution and accurate estimation of actual fault current coming into the grounding system are indispensible to optimun grounding system design. Especially, it is essential for efficient grounding design to estimate subsurface resistivity distribution quantitatively and logically. Accurate estimation of subsurface resistivity distribution has an absolute influence on calculating touch voltage, step voltage and ground potential rise (GPR) which are related with grounding design standard for human safety. In this study, thirty-three electrical sounding surveys were made in Yongdam Power Station to obtain detailed subsurface resistivity distribution and the sounding data were interpreted quantitatively using multi-layered model. The results of the quantitative resistivity models were adopted practically to calculate grounding resistance values. Analytical asymptotic equations and CDEGS program were used in grounding resistance calculation and the results were compared and reviewed in the study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.73-80
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• 2010

The grounding impedance is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode which shows the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical Length. In this paper, a new distributed parameter circuit model considering the condition of the multi-layered soil structures was proposed, and the grounding impedance and critical length of the vertical grounding electrode were analyzed by using the newly proposed simulation model and the MATLAB program. As a consequence, it was found that the effect of the soil structure on the frequency-dependent grounding impedance and critical length of the vertical grounding electrode is significant. It is desirable to consider the soil structure in optimal design of the grounding system.

• Electric Engineers Magazine
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• v.228 no.8
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• pp.52-57
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• 2001

Presently the Korean grounding system uses TN system, multi-grounding method with IT independent grounding method. Nevertheless TN system can't exist with TT system in the technological terms. If they coexist, it causes ground-fault circuit not to operate, and brings about different electrical potential rise by customer system. It brings about serious problems for safety. This paper aims for improving method of grounding system based on the technical analysis on instances in foreign countries and Korea. Almost standards and construction manner were apt to be internationalized after WTO/TBT agreement was concluded. The internal grounding systems should meet the international criteria and reliability for safety, and be provided with technologically impeccable standards.