• KIEE International Transactions on Electrophysics and Applications
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• 제2C권6호
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• pp.321-326
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• 2002

This paper describes the mechanical and electrical characteristics of insulating paper impregnated with diluted varnish(W-128), according to Korean Standards. The varnish was diluted with a solvent of 6 different wt%. Kraft paper and Nomex paper were impregnated with the diluted varnish in a vacuum condition, and then completely dried. As the mechanical characteristics, the thickness of the completely dried varnish, the drying time and the tensile strength of the specimens were measured, and as the electrical characteristics, the permittivity, the tan $\delta$ and the specific resistance were evaluated as well.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.472-475
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• 2003

In this paper, insulating varnish has been used for field magnet and armature impregnated insulating material of electric locomotive and traction motor. When it was duplicated coating, it could be accuse internal void, and which could change electrical characteristics. We used to boundary elemental method of simulation tool, and improved optimal insulating design of insulating varnish according to measuring electric distribution in void of specimen.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.299-302
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• 2001

In this study, we are studied the electrical conduction and dielectric breakdown properties of insulating varnish. In order to analyze the molecular structure and physical properties of insulating varnishs, FT-lR was used. As the result, it can be confirmed that the peak of alcoholic group appeared in wavenumbers 3452[cm$\^$-1], the peak of =CH appeared in 3080[cm$\^$-1] and the peak of -CH appeared in 2919[cm$\^$-1] respectively. The following results were obtained from electrical properties of insulating varnish. The amplitude of current density was decreased by thickness increasing and the current density was effected by the thermal energy from external due to temperature increasing. In study temperature dependence of dielectric strength, the specimen of 10[$\mu\textrm{m}$] thickness was measurement from room temperature to 180[$^{\circ}C$]. It is confirmed that the temperature regions below 60[$^{\circ}C$] is due to electron avalanche breakdown and the temperature regions over 60[$^{\circ}C$] is due to free volume breakdown which makes electron movements easy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기설비전문위원
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• pp.180-182
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• 2004

We have investigated characteristics of varnish and oil impregnant. When transformers are manufactured with some moisture and varnish impregnant not entirely dried, those should be caused by factors that deteriorate the electrical or mechanical property after installation. Therefore, in this study we experienced moisture content of the new insulating paper and the varnish impregnant paper in the ratio of time for confirming factors that deteriorate the paper characteristics. Besides, we investigated a property study that was experienced the value of dielectric strength and tensile strength as no serviced insulating samples of transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1983-1985
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• 2005

This paper describes moisture content, dielectric strength and dielectric properties of thermally accelerating aged insulating paper as varnish treatment. Kraft, nomex paper were impregnated with diluted varnish, varnish and solvent were diluted in the ratio of 40wt%, in vacuum condition, and then completely dried. To analysis of papers were influenced by varnish treatment, we applied thermal stress, and then measured moisture content, dielectric strength and relative permittivity, $tan{\delta}$ as varnish impregnated papers.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.313-316
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• 2003

Investigated about topology of each component of transformer and material choice method and property in this paper. Component of transformer is bobin, winding, insulating paper, Varnish etc. And, experiment and investigated special quality by primary winding of transformer and composition of secondary winding. Investigated loss of transformer and EMI decrease method. Investigated method to select winding size that consider frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1601-1603
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• 2003

Investigated about topology of each component of transformer and material choice method and property in this paper. Component of transformer is bobin winding, insulating paper, Varnish etc. And experiment and investigated special quality by primary winding of transformer and composition of secondary winding. Investigated loss of transformer and EMI decrease method. Investigated method to select winding size that consider frequency.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1712-1719
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• 2015

In recent days, there was a significant development on the electrical, thermal, mechanical, physical, chemical, magnetic and optical properties of the polyamide enamel, varnish and other insulating materials by the addition of nano fillers to it. Enamel was used in High Voltage Apparatuses used in Medical Electronics as insulation. Insulating materials determine the life time of the electrical apparatuses. The life time of the insulating materials was improved by the addition of nano fillers to it. Hence the life time of the electrical apparatuses was improved by the mixing of nano fillers to the enamel. In this research, the basic dielectric properties of the enamel and enamel mixed with nano composites of silica and alumina were analyzed and compared with each other. The addition of nano fillers has improved the quality factor and capacitance of the enamel. It was also observed that the addition of nano fillers has reduced the dissipation factor and dielectric losses of the enamel. Heat produced by the dielectric losses was also reduced by adding nano fillers to it.

• 전기학회논문지
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• 제68권1호
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• pp.52-60
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• 2019

In this paper, four types of insulation coils were fabricated by adding various kinds of glycols to improve the flexibility and adhesion of insulating coils in varnish dispersed with PAI / Nano Silica_15wt%. The applied voltage and frequency were 1.5 kV / 20 kHz for accelerated life evaluation. Through the 6th temperature stress level, the cause of the insulation breakdown of the coil was ignored and only the breakdown time was measured. The Arrhenius model was chosen based on the theoretical relationship between chemical reaction rate and temperature for estimating the insulation life of the coil due to accelerated thermal stress. Three types of distributions (Weibull, Lognormal, Exponential) were selected as the relationship between thermal stress model and distribution. The average insulation lifetime was estimated under the temperature stress of four types of insulation coils through the relationship between one kind of model and three kinds of distributions.

• 한국지반환경공학회 논문집
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• 제19권3호
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• pp.15-24
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• 2018

전자기파는 주변 매질의 전기전도도와 유전율에 민감한 영향을 받기 때문에 지반의 특성을 평가하는데 널리 이용되고 있다. 본 연구에서는 염수환경에서도 다양한 농도의 중금속을 검측하기 위하여 시간영역반사법을 이용한 전자기파 측정 프로브를 제작하였다. 중금속으로는 구리를 사용하였으며, 실내 실험을 통해 구리 농도에 따라 적용 가능한 프로브를 선정하였다. 실내 실험에서는 염도 3%의 염수에 용해된 구리의 농도가 0, 0.01, 0.05, 0.1, 0.5, 1, 5, 그리고 10mg/L가 되도록 8단계로 용액을 조성하였다. 프로브는 염수에서도 전자기파를 측정할 수 있도록 5가지의 각기 다른 절연재로 코팅하여 비교하였다. 코팅재로는 에폭시, 탑코트, 바니쉬, 아크릴페인트, 히팅튜브를 사용하였으며 코팅재에 따른 전자기파의 신호 특성을 분석하였다. 실험 결과, 아크릴페인트와 히팅튜브로 코팅된 프로브는 구리 농도에 따른 신호 변화가 관측되지 않았으며, 에폭시, 탑코트, 바니쉬의 경우 구리 농도가 증가함에 따라 반사된 전자기파의 전압의 크기가 감소하는 것으로 나타났다. 에폭시로 1회 코팅한 프로브와 탑코트로 코팅한 프로브는 구리의 농도가 5mg/L 이하일 때 민감한 반응을 보였으나 에폭시로 2회 코팅한 경우, 구리의 농도가 5mg/L보다 클 때 더 민감하게 반응하였다. 본 연구의 결과는 절연재로 코팅된 시간영역반사법을 이용한 전자기파 측정 프로브가 염수에 녹아있는 중금속의 농도를 평가하는데 활용될 수 있음을 보여준다.