Thermal aged XLPE cables restoration by injecting hydrolyzable voltage stabilizer

Underground power cables are prone to electrical tree aging and additives loss due to the harsh working environment. In this work, the thermal aged cross-linked polyethylene (XLPE) cables were restored by injecting a newly synthesized voltage stabilizer containing hydrolyzable siloxane groups. The voltage stabilizer functionalized siloxane groups greatly enhanced the electrical tree initiation voltage, significantly reduced the direct current (DC) conductivity and dielectric loss factor. The results of scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) indicated that the voltage stabilizer molecules were distributed in the electrical tree channels of the restored cables. After secondary thermal aging at 150 °C for 360 h, the characteristic electrical tree initiation voltage of the restored cable reached 12.10 kV, which was 66.90% higher than that of the unrestored cable. This indicated that the migration of voltage stabilizers could be inhibited by introducing hydrolyzable groups. This investigation provided a new approach to improve the migration resistance of the voltage stabilizer and the inhibitory effect of the rejuvenation liquid on the electrical tree.