Surface discharges on epoxy resin model post insulators initiated by moisture layers with low layer conductivity

Moisture layers with low layer conductivity are characterized by a low layer power (<50 mW) for the epoxy-resin-model post insulator under investigation. Under this condition no temperature-related dry zones appear, but partial microdischarges can occur, depending on the voltage stress, the surface properties and the relevant climatic conditions. Experiments under well-controlled conditions have been performed. The typical pattern of the partial-discharge behavior was established and simulated with the help of simplified equivalent circuit diagrams.<>