Evaluating Rejuvenation Effects on Water-tree Aged Cables Induced by Electric Field Using PDC Method

To explore the impact of different injection conditions on the water tree-aged cable rejuvenation effects and rate, including pressure injection and different voltage types injection, we conducted polarization and depolarization current (PDC) tests before and after rejuvenation. Results indicate that applying different external electric fields during the injection significantly enhances the rejuvenation rate, with the positive DC showing the best outcome, followed by AC, and lastly, the negative DC. Finite element analysis demonstrates that a DC field is more favorable for the accumulation of rejuvenation fluid molecules in the water trees. Under a DC positive electric field, both ends of the XLPE molecular chain are negatively charged and are aligned systematically due to the influence of the electric field force, providing a pathway for the migration of rejuvenation fluid molecules and achieving the best rejuvenation effect.