Experimental study of epoxy surface discharge under different frequencies

With widely use of power electronics in medium voltage level, there is increasing concern about behaviour of insulation material under arbitrary voltage stress. Solid-gas insulation is a general choice in medium voltage level. Therefore, it’s unavoidable to encounter surface discharge problem. In this paper, the surface discharge on epoxy-air interface is investigated, which is a commonly used insulation material. Point to plate electrode was used to test the surface flashover voltage and partial discharge (PD) behaviour at 50Hz, 500Hz, 1kHz, 2kHz and 5kHz. As the result, with increasing frequency, PDIV keeps roughly constant and flashover voltage first increases and then decrease, and the frequency obtaining highest flashover voltage is related to gap length.