Void and surface partial discharge pattern properties

Abstract

Phase-resolved partial discharge pattern are being used as a diagnostic tool since about 25 years. However, still up to now, often partial discharge pattern interpretation is considered as “black magic”. Many of the properties of such $\varphi-q-n$ pattern can be explained when understanding the underlying gas-discharge principles, the charge carrier generation (as well as their decay), the effects of the discharge site geometry, and the shape of the high voltage applied.