• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1471_1472
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• 2009

In a wide variety of high-voltage applications surface flashover plays major role in the system's performance and yet has not been studied in great detail for vacuum conditions with modern diagnostic tools. surface flashover for both direct current and pulsed voltages in considered. within the setup, parameters such as geometry, material characteristics of the applied voltage can be altered. This paper review surface flashover of insulator, primarily in vacuum. It discusses theories and models relating to surface flashover and experimental results. surface flashover of insulators in vacuum generally is initiated by the emission of electrons from the cathode triple junction point (the region where the electrode, insulator, vacuum). the electrode material was copper, and a AC voltage was applied between the electrodes. these results were compared with the surface flashover characteristic of insulator at results, surface flashover influenced only insulator surface condition. and increasing vacuum pressure was risen breakdown voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.597-600
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• 2001

In this paper, we evaluated the effect of accumulated charges on hydrophobicity of room temperature vulcanized(RTV) silicone rubber, which could improve the contamination performance of porcelain insulators, with uv radiation time. Outdoor insulating material could be charged by the corona discharge on field intensified area of insulator and discharge between the water drops. In addition, we performed the accelerated uv radiation on samples and investigated the change of charging decay with time. In this results, it is found that silica-like structure on the surface of RTV silicone rubber was formed by uv treatments and this layer have the characteristic of retaining the charges on surface for a long time. These charges have effects on its hydrophobicity and so adversely effects on contamination performance. Based on our results, we discussed the other degradation mechanism with well known ones.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.278-285
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• 1994

Aging test was done by loading back method for 20kVA amorphous core transformers manufactured by Hyosung Industries Co. and korea Electric Power Corporation. Iron losses, copper losses and insulation oil temperatures of the transfromers was measured for all the testing period. Expected life of amorphous core transformers on the basis of the degradation of the insulators was 46 years at 100% load, and 2.4 years at 130% load. Average temperature rising of transformer oil of amorphous core transformers was higher than that of silicon steel core transformers. Hence lowering the oil temperature by optimized design is needed for improving the expected life of the amorphous transformers.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.434-442
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• 1995

To improve dielectric and mechanical properties of insulating composite by plasma surface treatment, new plasma surface treatment process is designed with concentric and hemi-circle electrodes system. the plasma, which is generated between anode and cathode, is induced to the upper side of the electrode system and treats the surface of the insulators. The optimal surface treatment condition is that pressure : 0.5[torr], flux density : 100[gauss], discharge current : 500[mA] and treatment time : 3 minutes. The composite filled with glass cloth surface-treated by plasma shows the improvement in electric and mechanical properties, comparing non- and coupling agent treated samples.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.612-614
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• 2005

국내 배전계통에 90년대 중반이후 초기에 도입된 외국산 및 국산 폴리머애자를 현장에서 발취하여 특성을 평가하였다. 외관 관찰, 하우징의 발수성 및 경도, 전기적 특성, 하우징 재질의 변화특성 둥을 시험 평가하였다. 평가 결과 하우징은 발수성이 상실되었으며 표면에 열화가 진행되었다. 그러나 애자의 성능은 양호한 것으로 나타났다.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.929-931
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• 1998

The tracking characteristics of silicon rubber degraded by accelerated outdoor exposure employing a weather-o-meter have been investigated. The tracking test was performed according to IEC Publ.587 but the concentration of conductive material was two times higher than the IEC standard in order to accelerate the tracking failure. The number of large effective scintillation and the current of high voltage circuit were measured by changing two signals as voltage signals. It was fiund that the increase of exposure time resulted in the reduction of tracking resistivity except the fact that the specimens slightly degraded within 200 hours has slightly increased the duration time.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.866-868
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• 1998

Room temperature vulcanizing(RTV)silicone rubber has been widely used to coat porcelain insulators to render water repellency to prevent formation of water filming on the surface and thus to suppress the leakage current and consequent flashover. However, the electrical property and its hydrophobicity of RTV silicone rubber coating under outdoor conditions may be influenced by many environmental factors. In this study various treatments, such as salt-fog, salt water immerging and UV irradiation were applied to samples for investigation the change of the electrical property and hydrophobicity. As a result the leakage current increased and contact angle decreased as the degradation time longer. But the degraded RTV silicone rubber has recovered its hydrophobicity during the drying time in ambient condition because LMW(Low Molecular Weight)silicone fluid diffused from the bulk to the surface.

• Journal of the Korea Safety Management & Science
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• v.12 no.1
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• pp.1-9
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• 2010

Recently, in circumstantial situation it is recommended positively to utilize of EIFS(Exterior Insulating and Finishing System) as energy policy for economizing energy. But internal EPS insulators of EIFS are exterior panel of high fire risk, because of constituting of flammable materials to be fragile in fire. In this study, fire risk is assessed by experiment Con Calorimeter test and SBI(Single Burning Item) test. As the result of experiment, Con Calorimeter tests do not reach to capability standard of internal incombustible grade, and are assessed as low grade in SBI incombustible grade. Because EIPS is exterior material in buildings with high fire risk in spite of good efficiency, it is required rapidly to take measures to meet situation through various studies(for instance, adjusting law regulation, etc.) in the future.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.709-715
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• 1990

SiO2 films were nitrided by tungsten-halogen heated rapid thermal annealing in ammonia gas at temperatures of 900-1100\ulcorner for 15-180sec. The nitroxide films were analyzed using Auger electron spectroscopy. MIS caapcitors were fabricated using these films as gate insulators. I-V and C-V characteristics of MIS capacitors were investigated. The AES depth profiles of nitroxide film show that the nitrogen rich layer is, at the early stage of nitridation, formed at the surface of nitroxide film and near the interface between nitroxide and silicon. Nitridation of SiO2 makes the film have a larger effective average refractive index. The thermal nitridation of SiO2 on silicon causes the flatband voltage shift due to the change of the fixed charge density. It is found that the dominant conduction mechanism in nitroxide is Fowler-Nordheim tunneling. Rapid thermal nitridation of 200\ulcornerSiO2 on silicon results in an improvement in the dielectric breakdown electric field.

• Progress in Superconductivity and Cryogenics
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• v.15 no.3
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• pp.20-23
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• 2013

In the development of high temperature superconducting (HTS) power machines, HTS bushing is one of core technologies. In particular, the insulation body with sheds and electrical insulation at cryogenic temperature have attracted a great deal of interest from the view point of the size, weight and efficiency of bushing. In this study, the electrical and mechanical characteristics of various insulators for body in liquid nitrogen ($LN_2$) were investigated. And the surface discharge distance, collar length of GFRP sheds were studied. To emit bubbles between sheds, the shape and arrangement of shed were studied. The shed structure for 60 kV class HTS bushing were designed with regular arrangement.