Influence of void surface state on swarming pulsive micro discharge

The degradation examination on applying high voltage of high polymer insulation material used for an electric power cable has been conducted widely. In this degradation examination, a decrease and a disappearance of electric discharge current and maximum magnitude of discharge are observed with the lapse of time. This phenomenon is called SPMD; the discharge magnitude becomes very small, and then the electric discharge current pulse frequency per unit time increases greatly. It has been reported that this phenomenon is related to the roughness of the void surface. However, there are many unknown points yet. The relation between the degree of the roughness of the void surface and SPMD is investigated in this paper.