• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.19-21
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• 2003

In this paper, we studied on life-decision of underground cable of live-lines state. As all equipments have been wear, underground cables decided design-life on the whole 30 years because underground cable have been occurred aging as time goes. CV cable has been become about 30 years after installation in the South Korea, is come to a important point of time with estimation about life. Study target cable is 22 kV CV cables in this point of view and installation cable is about 10 years before and behind. Measurement method used dc leakage method of live-lines state that applied voltage of 50V in neutral point and data is analyzing result that is measured during 5 years. In this result, insulation resistance could confirm that change according to season and cause is effect of humidity, seasons and load current. Also, according as data is gone aging, insulation resistance by Weibull distribution could confirm functionally its decrease. As a result, the aging speed of cable that water tree is gone could confirm fastness very. Numerical analysis result, cable that water tree is not gone could confirm that life of cable that has passed 10 years remains about $10{\sim}20$ years.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.479-485
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• 2011

In 22.9kV underground distribution system, power cables are provided with multiple-point ground in which each neutral line of the distribution cable(A, B, C phases) and three-wire common grounded at every connecting section. But in such grounding methods, circulating current flows between the neutral wire and grounding wire. And power loss due to circulating current also occurs in all conductors. Therefore it is getting necessary reducing circulating current in underground distribution system. This paper presents improved grounding method to overcome such problems. The proposed grounding method eliminates circulating current in the neutral line effectively and is verified that there is no electrical problem or any ineffectiveness of operating protection systems. These analyses are carried out by EMTP/ATPDraw to compare each grounding methods in steady and transient state. This grounding method suggested in this paper can be applied on real distribution system after field tests considering elimination of circulating current was implemented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.702-707
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• 2018

In case of Lighting occurs in Domestic combined distribution line, normally the voltage for the neutral line increase dramatically. General connection for underground cable is bundled common earth type so the lightning over voltage increase at the concentric-neutral line is not big enough to give impact on cable sheath. But in case of Non bundled common earth type it is necessary to analyze the phenomena on cable sheath caused by lightening overvoltage. Especially pole and cable joint are the core factor to consider. In this paper concrete pole and cable joint were evaluated in case of Non bundled common earth type combined distribution Line. EMTP simulation model has been designed and several case study were made. Also several experimental test were made to verify the simulation result.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.85-93
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• 2008

In 22.9[kV]-y distribution systems, underground cables are provided with 3-wire loop multiple-point ground in which each coaxial-neutral line of the distribution cable lines(A, B, C phases) is 3-wire common grounded at every connecting section. In the underground cable distribution systems, circulating current flows in the coaxial-neutral lines and its magnitude amounts to about $40{\sim}50[%]$ load currents, even though loads are balanced. This paper presents a new ground method to overcome such a problem and a comprehensive analysis in tows of current capacity of power cables, induced voltage of cable sheath, and electromagnetic interference voltage from power cable lines.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.148-150
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• 2006

This paper describes the overvoltage at the branch line in underground distribution systems when the direct lightning surge strikes on conductor of overhead line. Distribution systems are very complex because it includes many branch lines, transformers, switches and so on. Therefore model system consists of overhead distribution lines, underground cable include branch lines, lightning source and switches. Analysis are performed using EMTP to understand and evaluate the surge behavior on branch lines considering various conditions in underground distribution systems. Simulation results show overvoltage with location in various cases. It is evaluated that result will be used to establish protection methods in actual underground distribution systems.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.4
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• pp.146-154
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• 2003

This paper describes various characteristics of the new compounds for cable jackets and model cables advanced in waterproof performance in order to essentially solve the problems of underground (URD) distribution class power cable failures. Several compounds were manufactured by the inclusion of additives to base resins available in Korea and tested for basic property, mechanical and electrical characteristics. Two model cables were created by using the compounds determined in the test as being the most appropriate for new structured model cable jacket material. The waterproof performance and mechanical strength of the new cable jackets were verified by applicable tests. As a result, MDPE and LLDPE compounds were superior as cable jackets in both mechanical and electrical characteristic aspects when compared with conventional PVC. In addition, the model cables composed of the new compounds based on MDPE showed good quality results in the water permeability test.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.672-676
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• 2017

Electrical energy is playing an increasingly vital role as the primary energy source in everyday life. With the increase in electric power consumption, power facilities are under an increasing stress and must operate at a high capacity. Consequently, the demand for electric power cables in power transmission and distribution lines is rapidly increasing. Underground distribution lines have been steadily replacing the aboveground lines owing to the increase in electric power demand and the need to increase the supply voltage. In addition to line damage, worker safety is of primary concern in this type of underground infrastructure. In this study, to improve the safety of workers dealing with underground transmission lines, we analyzed the electromagnetic field generated around the distribution line and determined the basic criteria for developing a device that can detect a live underground line.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.429-434
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• 2009

In this paper it was written about the safety management plan for underground power transmission cable, and it guarantees the reliable electric power supply and facility management to prevent an electric disasters according to that. Recently fires which happens on OF Cable lead to a breakdown of power system and cause a power outage of wide area and serious social problems. So it needs an improvement of inspection ability on OF cable as well as a strict inspection system to prevent that problems in advance and it will bring us the development of electric safety management and the reliable electric power supply.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1160-1161
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• 2015

In order to analyze and diagnosis on Location of partial discharge in underground distribution cable, partial discharges were measured using eletromagnetic sensors, oscilloscope, PDMS system at on-site underground multi-circuit switches. Throughout the analysis using 3-phase simultaneous pulse analysis and pulse polarity comparison of circuits, it is possible to separate noises and PD pulses and to find out the location of the pulses.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.30-40
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• 2013

In this study the method based on flux linkage in cell was introduced in calculation of eddy currents by cell method. According to this method eddy current distribution and the loss can be evaluated and since the shielding effectiveness by flux cancelation of eddy current can be analyzed, this method is applicable to design of conductive shield. And also the formula of shielding factor were so deduced as to be applicable to finite-width infinite-length shielding sheets and infinite-length underground cable shield. These formula are adaptable to magnetic materials as well as conductive materials. As the results of calculation in model shields are follows. In case of finite-width infinite-length shielding sheet, shielding effectiveness increases with increasing of conductivity. In case of infinite-length underground cable shield, the effectiveness become higher with increasing of permeability. Especially the effectiveness is very high in materials with both high conductivity and permeability in underground cable shield.