Abstract
Insulation system is one of the most important part of electrical devices. This insulation system is usually composed by solid part and liquid part. Oil impregnated insulation paper is used in transformers for many years. There are a lot of factors which have significant influence on the insulation system during the life time of electrical devices. Temperature is one of the factors which has strong influence on condition of oil paper insulation. This paper is focused on measuring of electrophysical properties of oil paper as relative permittivity, AC breakdown voltage and polarization index of insulation before and after thermal ageing. Vegetable oil paper insulation and mineral oil paper insulation were investigated and analyzed.
Highlights
IntroductionIn a liquid-filled transformer, the insulating liquid plays an important function by providing both the electrical insulation (in combination with a solid such as cellulose) and the means of transferring the thermal losses to the cooling system
In a liquid-filled transformer, the insulating liquid plays an important function by providing both the electrical insulation and the means of transferring the thermal losses to the cooling system
For the reliable operation of high voltage power transformers, it is essential that the cellulose insulation structures used in their construction are completely oil impregnated
Summary
In a liquid-filled transformer, the insulating liquid plays an important function by providing both the electrical insulation (in combination with a solid such as cellulose) and the means of transferring the thermal losses to the cooling system. For the reliable operation of high voltage power transformers, it is essential that the cellulose insulation structures used in their construction are completely oil impregnated. The oil impregnation procedure is important to ensure that no cavities are left inside the cellulose insulation and thereby dangerous partial discharges are avoided [2]. The thermal degradation affects electrical, chemical and mechanical properties of insulation paper. Natural ester insulating oils are non-toxic, more biodegradable and less flammable than a mineral oil. Conventional mineral oil is being replaced with natural ester insulating oil [4]. Influences of thermal ageing on the natural ester impregnated paper and mineral oil impregnated paper were researched
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