Experimental investigations of surface flashover characteristics of some common used insulation mediums under impulse voltage in vacuum

This paper has investigated the surface flashover characteristics of some common used insulation mediums, such as Nylon and Lucite, under an impulse voltage in vacuum with a set of experimental device. The half-angle of insulation frustum varied from 0 degree to 60 degree The rise-time and fall-time of applied impulse voltage were all 20 ns, and the flat-width of voltage varied from about 30 ns to 160 ns. The phenomena of surface flashover of each specimen in high vacuum have been observed. Based on the results of a series of experiments and computer simulations, the paper obtained the relationships between the thickness of insulator, the half-angle of frustum and the flashover voltage under impulse condition, and discovered the rule between field stress of triple-junction and actual flashover voltage. The results of this paper have been applied in the special insulation structure designing.