The influence of a DC test voltage on the AC performance of new and old XLPE cables

The main purpose of this work was to check if DC testing of XLPE cables could be harmful to the insulation. Tests performed both on new and aged Rogowski objects and cable samples showed no detrimental effects of DC testing. Some results supported the hypothesis that if a breakdown occurs during DC testing of aged XLPE insulation the rapid collapse of voltage might reduce the dielectric strength of the remaining insulation. In samples where the longest vented water trees were found to penetrate more than 50% of the insulation wall, the DC breakdown strength was found to be 1.4-2.2 times higher than the effective AC breakdown voltage