Space Charge and Conduction Current in Polypropylene Based Material Added Inorganic Filler under DC High Stress

We have investigated a space charge distribution and a conduction current characteristics in copolymerized materials of propylene and ethylene under high DC electric field at various temperatures, which are considered as one of candidate insulating materials for HVDC cable. The materials show excellent mechanical flexibility and relatively low conductivity at room temperature. However, at high temperature under very high DC applied electric field, electric field distortion induced by accumulated space charges in the bulk was observed. We attempted to improve the insulating properties of them by adding inorganic fillers into them. In this report, we describe measuring results of space charge distribution and conduction current in the composite materials under high DC electric field at high temperature.