DC Surface Flashover Characteristics of Polyimide at Low Temperature under Vacuum

Polyimide (PI) is widely used as insulation in various superconducting power equipments for its excellent dielectric performance and mechanical properties. The cryogenic vacuum is the actual work environment of the insulation systems of superconducting power equipments. Therefore, the study of polyimide film's DC surface flashover characteristics at low temperature in vacuum is of great significance. In this paper, a series of tests for studying polyimide film's DC surface flashover characteristics have been done at temperatures from 78K to 300K in vacuum by using the home-made test system which is developed for testing cryogenic electrical characteristics of dielectrics. The test results show that the surface flashover times and temperature both have some influence on the DC surface flashover strength of polyimide films.