Effect of voltage rise rate on space charge distribution in HDPE film [electrical insulation applications]

This paper describes the effect of voltage rise rate on space charge distribution in high-density polyethylene (HDPE) film. The observation of space charge distribution just before breakdown of HDPE films was carried out with short period interval (1 s) PEA measurement. A positive space charge was formed near the negative electrode irrespective of the difference of voltage rise rate. Up to electrical breakdown, this positive space charge formation was not remarkably changed at room temperature. The cathode electric field modified by the space charge effect was enhanced above the average field in the high field region. It was found that the average value of electric strength was about 4 MV/cm regardless of voltage rise rate at room temperature (25°C). From these results, it is considered that the electrical breakdown in HDPE film is possibly caused by positive hetero space charge, which enhances the cathode electric field just before the electrical breakdown.