“Mirror Image” Space Charge Distribution in XLPE Power Cable under Opposite Stressing Voltage Polarity

The paper presents the research on space charge distribution under different polarities in full size cross-linked polyethylene power cables using the pulsed electro-acoustic technique. Under both positive and negative voltage space charge distributions possess about the same profiles but opposite polarities. Similar phenomenon had been reported previously in plaque samples and was termed as “mirror image effect”. By comparing the results among the cables treated (degassing) under different conditions, the paper concludes that the “mirror image” charge distribution is mainly attributed to bulk effect within the volume of the insulation, whilst the electron transfer by tunnelling through an electrode/insulator interface contribute to the generation of homo “mirror image” at the vicinity of the electrode.