Space charge and anomalous discharge currents in crosslinked polyethylene

Transient currents in cross-linked polyethylene (XLPE) have been investigated by using different parameters: temperature T, electrical field E/sub p/ and hydrostatic pressure P. Anomalous discharging currents flowing in the same direction as charging currents were observed from T=30 to 70/spl deg/C, P=0.1 to 30 MPa and E/sub p/=13 to 33 kV/mm. The space charge was measured using the pressure wave propagation method (PWP). Theoretical calculation revealed that this anomalous behavior can result from charge migration under a partial blocking condition at the electrodes. We discuss theoretical results which are in reasonable agreement with our discharge current measurements.