High field dissipation current waveform of polyethylene film obtained by new method

Non-polar polymers, such as polyethylene (PE), polypropylene (PP) and so on, are widely used as insulators for power cable and capacitor. In ac high field region, it is known that carrier injection from electrodes is getting dominant, and then the dissipation current waveform shape begins to show a nonlinear property due to complex conduction mechanism, that is, charge injection, space charge effect, recombination and so on. To study the conduction mechanism under ac high field, a new dissipation current waveform observation method which enables detection of the harmonies with high accuracy is developed. By using low density polyethylene (LDPE) film, high field dissipation current waveform observations from room temperature to 90°C are carried out. Through these series of experiments, very unique properties which indicate the space charge effect under ac high field in high temperature are obtained.