• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1449-1451
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• 2002

A developed 800kV class composite hollow insulator for $SF_6$ Gas Insulated Switchgear (GIS) was tested as to insulation with their surfaces contaminated. The wet power frequency withstand voltage of the silicone rubber housing was about 135kV at an equivalent salt deposite density of $5kg/m^2$, to sufficiently satisfy the required performance. According to IEC 60507, the salt fog withstand voltage was measured at 565kV, and the highest measured leakage current was below 0.2mA. Therefore, it was clarified that the composite hollow insulator has sufficient insulation performance even when it is contaminated on the surface.

• Transactions on Electrical and Electronic Materials
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• 제6권6호
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• pp.294-300
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• 2005

According to the trend for electric power equipment of high capacity and reduction of its size, the needs for the new high performance electric equipments become more and more important. On of the possible solution is high temperature superconducting (HTS) power application. Following the successful development of practical HTS wires, there have been renewed activities in developing superconducting power equipment. HTS equipments have to be operated in a coolant such as liquid nitrogen ($LN_2$) or cooled by conduction-cooling method such as using Gifford-McMahon (G-M) cryocooler to maintain the temperature below critical level. In this paper, the dielectric strength of some insulating materials, such as unfilled epoxy, filled epoxy, and polyimide in $LN_2$ was analyzed. Epoxy is a good insulating material but fragile at cryogenic temperature. The filled epoxy composite not only compensates for this fragile property but enhances its dielectric strength.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1687-1689
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• 1998

In this work, the behaviours of conducting wire type particles within the coaxial electrode gap energized with high ac voltage have been systematically investigated using charge simulation method. For this, spheroidal charge is adopted as a image charge for the CSM analysis in order to calculate the acquired charge of the particles which are erected on the surface of the outer electrode. For this purpose, the effects of the lengths and diameters of Cu, Al particles in gas insulated system have been studied by a numerical computation and particle lifting voltage, lifting field, breakdown voltage, acquired charge and travelling distance have been considered. From this, we understand that the particle behaviours have different characteristics according to the particle lengths and diameters. And a possible countermeasure, based on the proposed simulation, has been provided with a view to estimating the flashover voltage of $SF_6$ gas under the 1 atm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.19-22
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• 2003

In the response to increasing the demands for electrical energy, much effort aimed to develop and commercialize 1MVA HTS power equipments that is supported by a grant from center for Applied Superconductivity Technology of the 21st Century Frontier R&D Program funded by the Ministry of Science and Technology is going on in Korea. For the development, the cryogenic insulation and winding insulation of it in this paper are discussed. In the first many types of dielectric insulating tests were carried out. In detail Breakdown characteristics of $LN_2$, FRP and turn insulating films, flashover characteristics along the FRP surface in $LN_2$ were verified after distinguishing insulation components in HIS windings. And then model windings were designed and insulation test was conducted. These included a AC withstand voltage test of 50kV rms and a lightning impulse test of 150kV at peak.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.15-18
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• 2003

Fault current limiters (FCL) are extensively needed to suppress fault currents, especially for trunk power systems heavily connected to high voltage/large current transmission lines. Due to its ideal electrical behavior, high-temperature superconductor fault current limiter (HTSFCL) becomes one of the most important developing trends of limiters in power system. This paper describes the result of an investigation of the dielectric characteristics of turn-to-turn insulation for pancake and solenoid type reactor coil in liquid nitrogen. The influence of thickness in a variety length, on AC, DC and impulse surface flashover has been investigated. Also, the relationships between the number of turn and breakdown characteristics were clarified. The information gathered in this test series should be helpful in the design of liquid nitrogen filled DC reactor type HTSFCL.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.263-263
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• 2008

This paper describes the electrical strength of a toughened glass stem insulators employed for electric railways. The broken glass stem insulators for comparison were taken at site. According to the international standards, electrical strength tests with 60[Hz] voltage and with impulse voltage were carried out to them under dry and wet condition and the results were corrected by considering the temperature and humidity factors. Based on the experimental results, the electrical strength of broken glass stem insulators was compared with those of sound ones and surface flashover characteristics were also discussed. As a result, it was confirmed that the electrical discharge is formed by bridging each end of the insulator shell. The experimental results are expected to be utilized as data for electrically identifying the failure causes of glass insulators.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.94-99
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• 2004

This paper presents experimental data from model windings with different arrangement of coil in order to provide information to design a 22.9 kV class HTS transformer. Before experiment, the composite insulation of two different type of HTS transformers are investigated. The first basic of investigation is a breakdown characteristic of liquid nitrogen and flashover characteristic on the GFRP surface under ac and impulse, The second investigation is insulation design, manufacture and test of model windings. These include a AC withstand voltage test of 50 kV rms and a lighting impulse test of 150 kV at peak.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2129-2131
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• 2005

최근 건축물의 대형화로 인해 대용량의 전기설비가 건물의 지하에 설치되고 있지만 전기설비에 대한 특별한 안전 대책 마련이 미비한 실정이다. 본 논문은 지하 구내에 설치된 몰드 변압기가 침수되었을 경우 발생될 수 있는 1차 재해와 2차 재해에 대한 피해를 최소화하기 위한 연구의 기초 단계로 실제 지하구내에 설치된 몰드 변압기를 실험 시편으로 선택하여 거리에 따른 연면 파괴 전압과 전류파형 등을 분석하였다. 분석결과 전극간 간격이 커질수록 연면방전전압이 증가하는 것으로 나타났으며, 방전전류의 피크치도 높아짐을 알 수 있다. 또한, 전극간의 간격이 커질수록 방전시간이 증가하였으며 방전시간의 증가로 인해 절연물의 손상도 증대되었을 것으로 생각된다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.267-269
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• 2009

In this paper, insulations characteristics by temperature changes($+10{\sim}-60[^{\circ}C]$) of $SF_6$ 9as in the experimental chamber were studied. From this result, The breakdown characteristics classify the gas & liquid coexisted stage of voltage value increases & much deviation and the $V_B$ low stage as the interior of chamber gets filled with mixture of $SF_6$ that are not liquefacted and remaining air which couldn't be ventilated. In addition the ability of insulation of liquid $SF_6$ was higher than that of the highly pressurized $SF_6$ gas. In this research, we want to provide the base data on designing insulation of high-temperature superconductor and the cryogenic equipments by investigating the insulation characteristics of $SF_6$.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.61-66
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• 2007

A transmission class high-temperature superconducting(HTS) power cable system is being developed in Korea. For insulation design of this cable the grading method of insulating paper is proposed. Two kinds of laminated polypropylene paper that has different thickness has been used as the electrical insulation material. The use of graded insulation gives improved mechanical bending properties of the cable. In a HTS cable technology the terminations are important components. A HTS cable termination is energized with the line-to-ground voltage between the coaxial center and outer surrounding conductors. in the axial direction. There is also a temperature difference from ambient to about 77 K. For insulation design of this termination, glass fiber reinforced plastic(GFRP) was used as the insulation material of the termination body, and the capacitance-graded method is proposed. This paper will report on the experimental investigations on impulse breakdown and surface flashover characteristics of the insulation materials for insulation design of a transmission class HTS power cable and termination. Based on these experimental data, the electrical insulation design of a transmission class HTS power cable and termination was carried out.