Study of space charge in polyethylene for cable insulation by direct probing

By utilizing the laser-induced-pressure-pulse (LIPP) technique, the authors quantitatively studied the behavior of space charge in polyethylene (PE) for cable insulation to clarify the space charge effects in power cables. Effects of crosslinking, carbon-loaded semiconducting layer and additives (antioxidant) are reported. Crosslinked polyethylene (XLPE) with metal electrodes showed negative homo charge near the cathode, suggesting that crosslinking enhances electron injection into polyethylene. XLPE with a carbon-loaded semiconducting layer showed both negative and positive homo charges near the semiconducting layers, indicating that both electrons and holes were injected from the semiconducting layer. The antioxidant greatly enhanced the accumulation of negative hetero space charge near the anode and thus enhanced the anode field. Space charge distribution in a cable sample was also observed