Study of the Interfacial Electrical Tree Growth Characteristics under AC and DC Voltages

The growth characteristics of electrical tree under AC and DC voltages are very different. In order to study the growth characteristics of electrical tree at the interface of cable accessories, in this paper, the growth and partial discharge (PD) characteristics of electrical tree at the interface between cross-linked polyethylene (XLPE) and silicone rubber (SIR) double-layer specimens were investigated under AC and DC voltages, respectively. The experimental results show that when under the AC voltage, the electrical tree channels gradually change from non-conductive to conductive during the growth towards the interface, and then breakdown occurs along the XLPE-SIR interface. When under the DC voltage, the electrical tree is a typical non-conductive tree with a small amount of partial discharge. When the electrical tree grows near the interface, some small lateral branches will be developed and no longer grow towards the interface. The results provides some experimental support for improving the safe and reliable operation of cable joints.