Defect diagnosis of the cable insulating materials by partial discharge statistical analysis

We made three layers of XLPE and arrayed non void sample on the upper layer and the lower layer. But we put air void and copper particles in the middle layer. After heating this to room temperature, 50degC, and 80degC in silicone oil, I studied the characteristics of partial discharge increasing electric voltage from inception voltage to breakdown. We obtained the following results by researching partial discharge which was occurred in an insulation material of XLPE, through partial discharge statistical analysis. When the K-means clustering was carried out at 9 kV for void discharge characteristic, discharge amount on the low temperature was small, but if temperature discharge amount on 80degC increased 5.7 times more than on room temperature as electric charge injection became easier. When 5 kV was applied to copper particles, K-means was conducted, and the temperature changed from 50degC to 80degC, amount of charge at positive polarity increased 20.3% and amount of charge at negative polarity increased 54.9%. On the kurtosis and skewness analysis, positive polarity and negative polarity showed clustering distribution of a straight line.