Abstract
AC partial discharge (PD) characteristics in air gap in series with fissure-like interface between solid insulating materials under needle-plate electrode system are studied at room temperature. The interface was formed by two insulating plates of epoxy resin and the minute interfacial gap and the surface roughness of the plates were changed artificially and their effects on the PD characteristics were studied. PD characteristics of specimens were measured with a pulse method using a computer aided partial discharge analyzing system.
The PD inception voltage is scarcely changed with the interfacial gap from 0μm to 400μm but becomes slightly lower for the specimen with smooth interface than that with roughened interface. The influence of conditions of the interface on PD characteristics, especially for the positive PD pulses, tends to be conspicuous. The roughened interfacial surface gives the larger positive PD magnitude with the minute interfacial gap near 0μm. When the interfacial gap thickness becomes large, however, the larger surface roughness is considered to prevent the surface discharge along the interface, resulting in the smaller positive PD magnitude.
