Study on the time evolution of partial discharge characteristics and interfacial phenomena of simulated XLPE cable joint

In this paper, time evolution of PD patterns and phase-dependence of waveforms of PD current pulses were measured by a computer system and a phase-angle gate control technique respectively, when the artificial defects were separately placed at the EPR / XLPE interfaces with or without silicone oil. As a result, PD patterns and current pulse waveforms obviously differed depending on the types of defects and aging duration. Moreover, rise time t(r) of PD current pulses varied slightly with aging time for each kind of defects. The variations of these PD characteristics have clearly indicated the transition of PD mechanisms and treeing due to the progressive degradation of XLPE insulation. An attempt was also made to interpret the results and interfacial effects of the simulated XLPE cable joint.