Temperature dependence of AC / DC breakdown strength of HVDC XLPE cable slices

Crosslinked polyethylene (XLPE) has been used for nearly sixty years for its high breakdown strength, low dielectric loss, good thermal stability and excellent mechanical performance. Since the good performances provided by HVAC polymeric cables, related research on HVDC XLPE cables has attracted much attention. In this paper, the temperature dependence of DC breakdown characteristics and AC breakdown characteristics of HVDC XLPE cable insulation are investigated by using column-column electrode system. The XLPE slices are cut spirally from the ±160kV extruded HVDC XLPE cable insulation with a thickness of 16mm. It is found that the DC breakdown strength decreases exponentially with the increasing of temperature, and the AC breakdown strength first increases slightly and then decreases and the maximum value appears in the vicinity of 70°C. And the DC breakdown strength of HVDC XLPE cable insulation is 1.3~3.5 times of its AC breakdown strength.