Measurement system for insulation performance investigation of graphite polluted insulator material under high voltage DC

This paper describes a measurement system to characterize dc insulation martials with respect to their behavior under polluted surface. The surface insulation performance was investigated by partial discharge and current measurement. The insulator support electrodes were designed in such a way that a uniform electric field acts onto the pollution particles and triple points are avoided. Two different rectangular shaped bulk materials (glass and PVC) were selected as insulation material and contaminated with graphite pollution. A photo camera was introduced to observe the pollution mobility during the experiment. The influence of the graphite pollution onto the surface insulation performance is negligible after a characteristic period of time (~30 sec) since the electrostatic force acting onto the mobile pollution causes a cleaning effect. Next step will be the investigation of the surface insulation performance for different (mobile/ immobile, dry/wet, conductive/ nonconductive) types of pollution and bulk materials).