Dissipation Current Waveform of Water Tree Deteriorated Low Density Polyethylene Sheet

Crosslinked polyethylene (XLPE) is widely used as the insulator for power cable. Water tree degradation phenomenon is the one of typical problem for the electrical insulation of power cable. In this paper, to confirm whether a signal of a fundamental component and the third harmonics peculiar to the water tree deteriorated sample appears by changing the applied frequency, the dissipation current waveform observations was carried out at 50 and 500 Hz. As the results of dissipation current waveform observation, it was found that the trend of the electric field dependence of both the fundamental component and third harmonics for the water tree deteriorated LDPE sheet sample considerably varied from that for LDPE without water tree at 50 Hz. However in the case of observation at 500 Hz, it was not admitted that a signal peculiar to water tree emerged in electric field dependence of both the fundamental component and the third harmonics in the water tree deteriorated LDPE sheet sample.