Abstract
The purpose of this paper is to grasp the partial discharge property of closed voids under the low vacuum involved in an epoxy resin. When an epoxy resin insulator is manufactured in a factory, some voids may be involved in it. To prevent the invasion, partial discharge is measured for insulators. However, partial discharge may not be detected due to the low vacuum in voids right after the manufactory. Well-known Paschen curve testifies this phenomenon, which describes the partial discharge property ranging from a high vacuum to the atmospheric pressure. However this Paschen curve is acquired several gases between parallel-plane metallic electrode gaps. There is little clear statement of Paschen carve on the void. Therefore authors of this paper studied the partial discharge characteristics of the void within the epoxy resin under the variable vacuum level.