The Influence of Charging on Solid Insulator Surface on HVDC Partial Discharge Activities and Flashover Characteristics in Air

An HVDC electrical insulation technique on electric field distribution, electric charging characteristics, partial discharge (PD) and flashover (FO) characteristics with and without solid insulator composite insulation systems in air were investigated. Firstly, it was clarified that the FO voltage characteristics in air are strongly affected not only by the PD activities from high voltage electrodes, called the PD stabilizing field relaxation effect, but also by the accumulated charges on solid insulators which originated from the ongoing PDs from HV electrodes. It was clarified that the affecting parameters leading to FO are the PD inception characteristics, followed by mutual interactions between the PDs and the accumulated charges on solid insulators. Because of these accumulated…