• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 추계학술대회 논문집
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• pp.147-151
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• 1994

In order to investigate the dielectric characteristic insulating oil is chosen insulating oil for electric cable, and experiment is performed in the temperature range of 30∼120[$^{\circ}C$] and frequency range of 30∼1${\times}$10$\^$6/[㎐]. As a result, the observed linear decrease in tan $\delta$ value at the low frequency range is due to the influence of frequency, whereas the increase in tan $\delta$ value at high frequency range is contributed by the electrode's resistance and dielectric loss. The dipole moment and activation energy of specimen are obtained 1.22(debye) and 12.75∼18.66[㎉/㏖e] of high temperature region, 15.68 ∼ 20.6[㎉/㏖e] of low temperature region respectively.

• 한국화재소방학회논문지
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• 제23권2호
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• pp.62-66
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• 2009

본 연구는 국내에서 사용되고 있는 누전차단기 외함 절연재료의 소손 특성에 대하여 연구하였다. 시료는 3개 제조사의 누전차단기 외함 절연재료를 사용하였으며, 시료의 열분해특성, 연소특성, 트래킹 특성 등을 비교 분석하였다. 열분해특성은 TGA를 사용하였으며, 연소특성은 ISO5660(Fire Tests - Reaction to Fire, part 1)을 만족하는 Mass Loss Calorimeter(FTT 사)를 사용하였고, 트래킹 특성은 고체 절연재료의 내트래킹 및 비교트래킹 지수를 측정하는 실험인 KSC IEC 60112.의 기준에 따라 분석하였다. 연구결과 A제조사의 경우 내트래킹성이 가장 우수하였고, B제조사의 경우 내트래킹성이 가장 낮은 반면 $350^{\circ}C$ 이상의 고온에서 열안정성이 가장 우수하였으며, C제조사의 경우 $400^{\circ}C$ 이하의 온도에서 열안정성이 가장 우수한 것을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제25권10호
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• pp.791-797
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• 2012

Mineral insulating oils are an important insulating materials in oil-filled transformer. However, the mineral oil is the cause of the environmental problem. The vegetable oils are substitutes for mineral oil because of its biodegradability characteristic. As large size and high rating of the transformer increases, the losses increase at a faster rate. So insulating oil is forced circulation in the oil-filled transformer by using oil pumps. The flow electrification occurs when insulating oil was forced to be circulated. To check the flow electrification, had conducted experiments varying factors. As a result, the streaming electrification could see the changes according to flow velocity, oil temperature and insulation materials.

• 대한방사선기술학회지:방사선기술과학
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• 제9권1호
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• pp.73-81
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• 1986

This paper carried out an experiment on the characteristics of time, temperature, electric field and the dependense of electrode materials and gap length by the conduction current of the insulating oil used for x-ray tube housing. The obtained results can be summarized as following: 1. In the x-ray tube housing insulating oil with vacuum condition, conduction current is declined more than the x-ray tube housing insultaing oil with the air, and is held stable states. 2. At the low electric field the higher temperature of the x-ray tube housing insulating oil is increased, the more conduction current. 3. The dependence of electrode material is appeared at the low electric field and the short gap length than the high and the long with Fe> Cu >Al. 4. At the I-E characteristics, the low electric field than 1000 [V/cm] is appeared Ohm's law region, and the high become saturation region. 5. At the same electric field, the longer gap length become, the more conduction current is increased, and the same applied voltage, the longer, the less conduction current is decreased, the less low than high temperature x-ray tube housing insulating oil.

• 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.

• 한국전기전자재료학회논문지
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• 제28권8호
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• pp.508-512
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• 2015

Some insulating materials are tested and analyzed with variables to obtain the reliable pressboard which is located to core and coil of high voltage transformer. The high voltage transformer is used in electrical power system and operating reliability. Optimization possibility of pressboard shape including electrical insulation performance could be achieved by analysis simulation. Using insulating pressboard, which is made by mold applied eddy current loss, it could be measured the influences of moisture content for electrical properties. As a result, it is to contribute to improve the performance and ensure the reliability of the pressboard by investigating electrical strength according to the variation oil temperature. In addition pressboard thickness is important design factor to ensure electrical strength in high voltage transformer.

• 전기학회논문지
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• 제61권6호
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• pp.821-826
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• 2012

The streaming electrification process of vegetable insulating oils occurring when the oils contacted with solid material in a high power transformer circulation system seems to cause electrical discharge incidents and may cause failures. We therefore measured the dielectric breakdown voltage tendency of vegetable insulating oils flowing on the surface of the charging device with various velocity and temperature. First, the relation between the velocity and breakdown voltage tendency of vegetable oils, can be explained by volume effect and v-t effect. Second, experimental results show that applied voltage have little effect on dielectric breakdown voltage, when vegetable insulating oils used for large power transformer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.82-85
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• 2008

Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.226-229
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• 2003

Following the successful development of practical high temperature superconducting (HTS) wires, there has been renewed activity in the development of superconducting power equipments. HTS equipments must be operated in the coolant, such as liquid nitrogen (L$N_2$) or cooled by cooler, such as GM-cryocooler to maintain the temperature below critical temperature. In this paper, dielectric strength of some insulating materials, such as epoxy, teflon, and glass fiber reinforced plastic (GFRP) in L$N_2$was measured. Surface breakdown voltage of GFRP which is basic property in design of HTS solenoid coil was measured. Epoxy is a goof insulating material but it is fragile at cryogenic temperature. The multi-layer insulating method of current lead is suggested to compensate this fragile property. It consists of teflon tape layer and epoxy layer fixed with texture. Based on these measurements, the 6.6㎸ class HTS magnet for DC reactor type high-T$_{c}$ superconducting fault current limiter (SFCL) was successfully fabricated and tested.d.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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• pp.61-64
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• 2003

The degradation of the dielectric properties of insulating papers that were used under loaded conditions at cryogenic temperature was paid attention. Electrical and tensile stress properties of dielectric paper at cryogenic temperature have been investigated to optimum insulating design of high-Tc superconducting(HTS) cable. Tensile strength of PPLP in liquid nitrogen was high more than that of air, but tensile strain could know that decrease sharply. According as tensile strength increases, the breakdown stress of PPLP in liquid nitrogen was decreased.