Partial discharge theory and applications to electrical systems

Partial discharge monitoring is an effective on-line predictive maintenance test for motors and generators at 4160 volt and above, as well as other electrical distribution equipment. The benefits of online testing allow for equipment analysis and diagnostics during normal production. Corrective actions can be planned and implemented, resulting in reduced unscheduled downtime. An understanding of the theory related to partial discharge, and the relationship to early detection of insulation deterioration is required to properly evaluate this predictive maintenance tool. This paper presents a theory to promote the understanding of partial discharge technology, as well as various implementation and measurement techniques that have evolved in the industry. Data interpretation and corrective actions are reviewed, in conjunction with comprehensive predictive maintenance practices that employ partial discharge testing and analysis.