Degradation of solid dielectrics due to internal partial discharge: Some thoughts on progress made and where to go now

The amount of literature on partial discharge (PD) and partial discharge induced degradation is vast. In the past 10 - 20 years significant progress has been made on research within partial discharge induced aging of dielectrics. Researchers now agree on the main mechanisms pertaining to this topic. With the advent of a new generation of dielectrics of which many properties now can be affected by the introduction of small amounts of nano-sized particles it seems to be a good moment to review the progress on the understanding of PD induced aging. Focusing on internal partial discharge in solid polymeric insulation this paper tries to identify achievements and at the same time challenges still to be solved.