Investigation on the evolution of discharge behaviors at XLPE-SiR interface of 10 kV cable joints under moisture conditions

The discharge behaviors at the XLPE-SiR interface of 10 kV cable joints under moisture conditions seriously affect the reliability of the distribution network. However, there have been few studies on the development and characteristics of interfacial discharge behaviors. In this paper, an investigation was conducted to replicate the discharge behaviors at the XLPE-SiR interface of 10 kV cable joints under moisture conditions. Both optical and electrical characteristics were measured during the process. The results indicate that water initially triggers partial discharges at the XLPE-SiR interface, gradually evolving into arc discharges. The early discharge has two effects: on one hand, it causes pyrolysis of the insulating material, forming conductive traces; on the other hand, the heat generated by the discharge leads to the evaporation of water, effectively preventing the continuation of discharges at the interface. Subsequently, the discharge behaviors at the XLPE-SiR interface were further investigated in the presence of electric traces. The results indicate that when there are electric traces at the XLPE-SiR interface, moisture can rapidly lead to the interface breakdown. The findings contribute to the establishment of effective fault identification strategies for 10 kV cable joints, enhancing overall system reliability.