Abstract
A space charge distribution in a low-density polyethylene (LDPE) film is considered to change when the electric field becomes as high as its breakdown field. Since the space charge profiles measured at a few seconds interval did not show any noticeable change, we have developed a short time interval space charge measurement system. To investigate the relationship between the electrical breakdown and space charge behavior at high temperature region, the measurement system is designed to use at 90°C. The experimental results using a 100μm thick LDPE film show a large amount of positive charge was injected from anode at 3MV/cm just before the breakdown. To clarify the relationship between the positive charge injection and electrical breakdown phenomena, acetophenone-coated LDPE film samples at either anode or cathode surface were prepared. In the acetophenone-coated sample at anode surface, a significant packet-like positive charge appeared just before the electrical breakdown at 3 MV/cm. Although a negative packet-like charge appeared in acetophenone-coated sample at cathode surface at 3 MV/cm, the electrical breakdown did not occur. Based on the experimental results, it is clear that the breakdown phenomena in the LDPE film at 90°C in influenced by space charge behavior, i.e. a large amount of positive charge injection from the anode.
