Insulator charging phenomena in air under non-uniform fields with DC voltages

A considerable amount of research work has been reported on charging phenomena of insulating surfaces. Most of these studies have been confined to either contact electrification of insulating surfaces and charge decay from insulating films [1], or corona behaviour of insulating materials [2]. All these studies seem to indicate that charging of insulating surfaces under dc voltages can pose a serious threat to the performance of insulators; but the phenomena is far from clear, especially in non-uniform fields under surface and space charge conditions. The authors have, therefore, made an attempt to study the charging phenomena and its effect on corona inception characteristics in hemispherically capped rod-to-plane air/insulator gaps using dc voltages.