• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2136-2138
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• 1999

In this study, we describe the change of electrical properties of XLPE with electrical-tree degradation. XLPE insulation was used as specimen which was cut off from 22.9kV XLPE insulated cable and made in a type of block. The applying voltages are 8kV, 10kV, 12kV and frequency is 60Hz Ogra needles having tip radius of 10$\mu\textrm{m}$ were inserted in blocks. PD quantity and $tan{\delta}$ and DC current were measured from inception of tree to breakdown and their characteristics were analyzed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.114-120
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• 2008

XLPE cable is using insulator for Cross Linked Polyethylene(XLPE), because insulation Performance is superior and easy comparatively. Need systematization of accident transaction for electrical equipment accident, It is no disposal standard for defect of manufacture and second to accidents. in this paper deals with the change of XLPE cable insulation. To understand the electrical properties of XLPE insulation. Made of XLPE block sample, Penetration fracture Sample and flashover sample. Ogura needles having tip radius of $10[{\mu}m]$ were inserted into each sample. AC voltage of 1[kV/sec] increased at 60[Hz] were apple to breakdown sample and flashover sample. AC voltages of 12[kV], 17[kV] at 60[Hz] were a lied to XLPE block sample. The electrical properties of specimens were measured were measured from initiation of tree and breakdown to their characteristics were analyzed.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1550-1552
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• 1994

In order to investigate the effect of electrolyte solutions on the activities of bow-tie water trees in XLPE insulated power cable, we have tried to observe the characteristics on water treeing ( bow-tie type ) using several electrolyte solutions such as $CH_3COOH$, $MgCl_2$,HCl and NaCl solution and tap water. Bow-tie tree density in $CH_3COOH$ and $MgCl_2$ solution was higher than in any other solution, and the growth of tree was stimulated in NaCl and $CH_3COOH$ solution, and diffusion of bow-tie trees into insulation in $MgCl_2$, HCl and NaCl solutions was faster than in $CH_3COOH$ solution and water. Also, although the increase of applied voltage caused bow-tie tree density to be high, it didn't affect the growth of tree maximum length noticeably.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.258-263
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• 2004

The purpose of this experiment is to modify diagnosis criterion of isothermal relaxation current(IRC) measurement equipment which is using for distribution cable diagnosis. We're using this system for several years in the field instead of DC leakage current measurement and lots of cables were replaced. But we have to investigate on the reliability of this equipment for our cables because we didn't carried out condition assessment of extracted cables after field diagnosis by this equipment. It is important thing for cable maintenance. If the replacement criterion is improper we can not prevent failures or will waste budget on account of replacement of the sound cables. In this paper we selected field installed cables and injected silicone fluid to the cables for insulation rehabilitation. In order to prove reliability of the diagnosis equipment we compared diagnosis results and AC breakdown strength according to operating time after silicone treatment. This is the results of the field test for 1 year.

• Journal of Korea Technology Innovation Society
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• v.4 no.2
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• pp.157-171
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• 2001

This paper discusses the economics of local loop architecture focusing on existing technologies, ADSL, HFC, and new one, PLC, and suggests a new modeling approach of access network system and the numerical equations. To modelize access network system and drive the numerical equations, we consider the double star and the tree & branch architecture and made block diagram of each access system. In addition, we introduce the density of subscriber as a variable and the equation of seeking the optimal number of cell in a service area. The economics of local loop architecture is analyzed in two ways, i.e. with and without consideration of the cost of cable and infrastructure. From the numerical analysis, we find that in case of not including the cost of cable and infrastructure, there is no much difference in the cost per one subscriber, while, in case of including it, there is remarkable difference among technologies. Therefore we conclude that the economics of local loop architecture is depend on the density of subscriber and existing network infrastructures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.111-115
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• 1997

There exists a interface among the different kinds of materials in the solid insulating ones, which effects on the insulating capability heavily. The insulating construction has been developed for each usages and take themselves into several sorts. The conjunction between CV cables have the electrical weakness of solidity and solid interface, so they were focused at the long distance-line. To this background, it is very important to get the information on the interface influencing on the insulating capability of cable and to observe its procedure. In this paper, the interface was made artificially to research the effect owing to the toughness of interface, which results in the aging and treeing proceeding was observed. The polyethylen, as is generally using for the cable, was taken in this research.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.187-189
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• 1997

Thermal and electrical breakdown phenomena in XLPE insulator of power cable were investigated. At high temperature the polymeric insulator was thermally deteriorated. Under the magnified high electric field, electrical tree was initiated at the sharp tip of needle electrode which was inserted to simulate the defects and impurities such as void, crack, metallic particles, dusts, and so on.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1725-1727
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• 1998

In this paper the patterns of partial discharges(PD) occurred from some defects at the interface of cable joints as the function of the phase of the applied voltage were investigated in order to discern the kind of a defect. The results obtained in this study show that it is possible to distinguish the PD patterns between the void discharges and the treeing or tracking discharges which were occured at the cable joint interface. While the state of defect transfers from a void discharge into a tree or tracking discharge with a aging time, the skewness for both half of the applied voltage cycle is observed to go to the negative value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.57-61
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• 1999

Electrical stress makes insulating materials aged finally resulting in the dielectric failure. It becomes more and more important to recognize the degree of aging and the life time of the insulating materials since it is directly concerned with the reliability of the insulation system. In this paper, the life time of the Cross-linked Polyethylene(XLPE), the insulation layer in the 154kV-grade power cable, is expected and calculated using statistical and mathematical methods. The simulated results are compared with experimental ones and the life exponent of the material is obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.221-222
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• 2007

The test method on materials of electrical power cable are used in accordance with 18 specifications of IEC, ICEA, KS and KEPCO Spec. The validation of test methods were checked and established by solving the problems occurred during the test. These tests are tensile strength, hot creep, shrink back, environmental stress cracking, flammability, oxygen index, absorption coefficient, differential scanning calorimetry, amount of ion in semiconductor, void, amber, contaminant and water tree etc. The performance test of power cable made by A, B, C, D company were evaluated and compared.