Partial Discharge Characteristics for Small Gap of Electrode/Epoxy Interface in SF6 Gas

To achieve a safe operation of gas insulated switchgears (GISs), the reliability of electrical insulation is one of the fundamental importance. For this respect, there is an urgent need for better understanding of partial discharge (PD) mechanisms at different locations in GIS. In the current work, the PD inception characteristics at electrode/epoxy interface at insulating spacer in GIS, which represents one of the most critical defects in GIS, are obtained and investigated with different gap lengths, 50~500 mum. Partial discharge inception voltage (PDIV) and electric field (PDIE) are measured and analyzed regarding PD inception mechanism in SF₆ gas. Also the dependence of PDIV on repetitive number of PD pulses is obtained and discussed from the viewpoint of accumulated charge on the epoxy surface.