Experience with on-line partial discharge analysis as a tool for predictive maintenance for medium voltage (MV) switchgear systems

Partial discharge (PD) online monitoring of MV switchgear was implemented in several large industrial plants beginning in 1998. A switchgear manufacturer completed offline testing and calibration to determine the type and location of sensors for measuring the effective sensitivity of partial discharge activity. This paper also presents actual pending failures, which were identified and prevented by online PD monitoring. The pending failures include bus corona damage, CT corona damage and failing insulation due to surface tracking. An update of new continuous online partial discharge monitors for MV switchgear is also included.