Measurement and simulation of partial discharge in disc-void of oil-pressboard insulation with electrical degradation process

The continuous test on oil-pressboard insulation with internal disc-void was developed and the phase resolved partial discharge pattern (PRPD) of partial discharge (PD) signals during electrical degradation process was measured. It shows that the PD pattern could be classified into five stages and great diversity in first four stages is observed. The computer numerical simulation model which is based on a physical discharge process was established. The causes of PD pattern change were interpreted by comparison to computer numerical simulation results. The model parameters in different stage have been studied and insight into the physical changes in the void during electrical degradation. The results provide rules for the identification of the electrical degradation stage by the partial discharge measurements.