Partial Discharges in XLPE Insulated Cable under Superimposed Transient Voltages

This paper investigates the partial discharges (PD) at artificial defects in a cross-linked polyethylene (XLPE) insulated cable joint under superimposed voltage. The experiments are conducted on a 16-meter long 150 kV commercial XLPE cable, together with a cable joint and two terminations. Defects are fabricated on purpose in the cable joint. The cable system was subjected to a 50 Hz AC voltage, being in between PD extinction and inception values, superimposed with a lightning impulse voltage. Partial discharges are measured by two HFCT sensors at the two ends of the cable joint. The measurement results show that, the impulse voltage could trigger partial discharges. The partial discharge occurrence is mainly influenced by the time period during which the applied voltage is higher than PDIV.