Insulation status diagnosis of XLPE cable based on polarization and depolarization current (PDC)

Cross-linked polyethylene (XLPE) insulation cable is widely used in distribution power system, so it is important to reasonably estimate cable insulation status. Cable insulation is mainly affected by high temperature and water tree. Therefore, in this paper, we use PDC method to evaluate cable insulation, which is non-destructive due to its low voltage. In order to find out the relationship between PDC curve and aging status, we put 5 single-core cable samples in oven and set aging temperature as 14°C. Then, we divide these samples into different aging time (new, 10 days, 20 days, 30 days, 40 days) and measure the PDC curve. The result shows that with the increase of aging time, the PDC curve decreases quicker and the absolute value of steady current becomes higher. PDC will be a very practical way to judge cable insulation in the future.