Electrical Tree Growth Structural Analysis of XLPE Cable Insulation under Different AC Voltage

The presence of partial discharge (PD) activities degrades the insulation strength and reduces the life span of in-service high voltage XLPE cable. The insulation properties are deteriorated by various factors, such as thermal-aging, electrical-aging, mechanical-aging, and environmental conditions. The main causes of the deterioration are the discharges, due to void, crack, contamination of impurities, etc. If these discharges continue for a certain period, it replicates several carbonyl channels which are known as an electrical tree. The growth rate of treeing phenomena implies a sudden and complete breakdown of in-service cable. This work primarily focuses on the PD measurement, fractal dimension analysis, and electrical tree growth characteristics analysis with respect to time in a 33 kV, 3 core XLPE cable insulation sample. Needle-to-needle electrode configuration is used to investigate the various type of tree structure formation with respect to their PD activities. The Box-counting method is implemented to analyze the fractal dimension which provided information on the volume of damage. The structural deformation of XLPE sample during the tree growth period is examined using ImageJ.net by surface plot analysis.