Degradation of insulating polymer materials exposed to partial discharge under NOx environment

The purpose of this study is to investigate the effects of humidity and NOx on partial discharge by insulating polymer materials degradation. Insulating polymer materials were used for the low density polyethylene (LDPE). The accelerated testing of these insulating materials was conducted. Experimental conditions are air atmosphere mixed with NO concentration of 600 ppm, and relative humidity was varied to 0, 25, 50, and 75 %. The quantity of partial discharge pulses can be evaluated with number of pulses, average pulses, maximum of pulses, and summation of pulses during 20 ms. The degradation factor of each sample was compared and examined from this quantity of partial discharge pulses.