On-site condition assessment of HV cable terminations in service

The ultra-high frequency partial discharge detection method described in the paper is successfully applied on-line to assess the insulation condition of plug-in cable connectors. A portable screening housing with the UHF sensors inside is clamped around each tested termination in turn. PD signals recorded in the time-domain by a programmed oscilloscope are plotted as a function of the phase angle. FFT transforms of the PD pulses are used to differentiate between internal and external (corona) PDs. Experiences from a field testing are reported as well. Results of the visual inspection of the connectors retrieved from the field proved the effectiveness of the method. The diagnostic system can be applied as a quality check on just assembled terminations, as well as for the purposes of the condition assessment of insulation integrity after years in service.