High voltage DC partial discharge and flashover characteristics with surface charging on solid insulators in air

Electrical insulation for high voltage DC (HVDC) applications exhibits many features that differ from those of conventional AC insulation. It is therefore necessary to concentrate research activities on aspects that will facilitate a better understanding of its performance, e.g., DC-partial discharge activity, charging characteristics on solid insulator surfaces, and electric field distributions. All of these are complex phenomena and are not yet well understood [1]-[7].