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Reference: ISH2015_502

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Electric Characteristics of Dry-type Polyester Film Insulation with Different Thermal Aging States



The dry-type air-core reactor is composed of several coils insulated by polyester film with good insulation capability and enclosed by epoxy resin impregnated with long glass fiber. The dry-type air-core reactor accidents show that turn-to-turn insulation failure is the most common one occurred during operation of air-core reactor. Such failure often leads to short circuit of turn-to-turn insulation and further burns the reactor. The extensive researches on thermal aging analysis mainly focus on oil-impregnated paper in past decades, but barely dry-type insulation materials. The objective of our thermal aging experiment is to develop a correlation between thermal aging and electrical as well as mechanical characteristics of polyester film. All these are done through an accelerated thermal aging process to simulate the normal operating conditions. In order to acquire specimen with different aged status, new polyester film samples are thermally-accelerated aged, using the 10 degree regulation, for different time intervals. The thermal aging process is performed in a temperature controlled using an oven. The basic dielectric parameters are compared for different aged samples. Partial discharge (PD) tests were examined using artificial void defect. A breakdown voltage test and insulation resistance test is also applied on each polyesters sample with different aging states. As an addition, the tensile test strength also applied to observe the mechanical characteristic change. Throughout the tests above, the aging characteristics of polyester film samples are summarized.

File Size: 442,5 KB

Year: 2015

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