Effect of Semiconductive Layer on Space Charge Accumulation in XLPE

Long time DC pressure on high voltage cables will lead to the accumulation of space charge in XLPE cables, thus endangering cable insulation. In order to study the effect of the thickness of semiconducting layer on the space charge in XLPE, the space charge in 10kV and 220kV XLPE sample with different thickness of semiconducting layer was measured and compared based on PEA method. Firstly, the samples were pressurized to the specified voltage, then kept this voltage for 30 minutes, then depressurized to 0, and lastly maintained for 90 minutes. The variation of space charge distribution during the pressurized stage was analyzed with the space charge density as the characteristic parameter. The results show that the space charge near the anode and cathode is accumulated by the semi-conductive coating during the period of maintaining pressure; the thicker the semi-conductive layer is, the more obvious the accumulation of space charge is; the longer the time of maintaining pressure, the more space charge accumulates.