Wide and narrow band PD detection in plug-in cable connectors in the UHF range

Experience in on-line UHF partial discharge detection on high voltage plug-in cable connectors (terminations) for GIS and transformers are presented. Narrow vs. broadband, as well as zero-span measurements were carried out using a spectrum analyzer on a laboratory setup with a built-in artificial PD defect of variable intensity. A sensitivity below 5 pC turned out to be detectable by the presented UHF method. The results of the laboratory experiments demonstrate high effectiveness of the on-line UHF PD detection in plug-in cable terminations. The method can be applied to proof the quality of assembly work during commissioning as well as on a regular basis after many years in service to detect aged and risky terminations as a part of the condition-based maintenance.