Epoxy/mica insulation condition assessment using AC current method

Abstract

In this paper, accelerated multistresses aging tests in the laboratory have been conducted on electric machine stator epoxy/mica insulation. In different aging stages, AC current tests and breakdown tests were performed. The characteristics of AC current of stator insulation were analyzed and the voltage U/sub pi2/, at which the second point of current rapid increase appears, was investigated. The correlation between the voltage U/sub pi2/ and the residual breakdown voltage was also analyzed.