Purpose/Aim
In the process of cable manufacturing, transportation, laying and operation, it is inevitable to cause some  defects in the insulation layer. In case of line failure or emergency power supply, the temporary overload operation of the cable leads to short-term temperature rise. High temperature is easy to cause partial discharge of potential defects of XLPE cable, which leads to insulation deterioration and endangers the safe operation of the cable.
Experimental/Modeling methods
In this paper, a temperature-controlled AC branch-partial discharge test system was built. The pin-plate electrode was used to simulate the field intensity concentration area in cable insulation, and the images and partial discharge signals during the growth of electrical branches were collected to compare the partial discharge characteristics of XLPE at different temperatures.  
Results/discussion
With the increase of temperature, PDIV gradually decreased and the partial discharge time was significantly shortened. At 1.2 and 1.5 times of PDIV, the PD amplitude of the discharge dense region in the prpd spectrum increases with the increase of temperature, and the electrical tree presents different forms.
Conclusions
The high temperature intensifies the deterioration of XLPE cable defects,which seriously threatens the safety and reliability of AC XLPE cable.
 

pattial discharge;high temperature;electrical trees