Study on Insulation Performance of Thermal Aging XLPE Cables by Direct Current Integrated Charge Technique

The effect of thermal aging on the insulation performance of XLPE cables is studied using a new diagnosis technique-direct current integrated charge (DCIC-Q(t)). The influence process of thermal aging on crosslinked polyethylene (XLPE) and the measuring principle of DCIC-Q(t) were described. Several thermal aged XLPE cables were obtained for DCIC-Q(t) experiments. The dynamic charge curve of cables under different thermal aging conditions is obtained, and charge ratio $R$ is proposed to compare the charge injection and accumulation. The permittivity $\varepsilon_{r}$ and conductivity $\gamma$ of XLPE insulation are calculated to analyze the aging level of XLPE cable insulation. It can be concluded that this technique can be useful to monitor the aging of the full-sized cable and has potential to applying in other insulation system.