How to deal with the severity of different Partial Discharge sources in rotating machines: the definition of a new Health Index

There are two thought trends concerning partial discharge, PD, measurements and diagnostics in electrical insulation systems. One is make it simple and refer to PD amplitude and repetition rate. The other is try to identify the typologies of discharges and focus on each type of source generating PD for diagnostic and maintenance decisions. In this paper, an approach towards the determination of a health index for rotating machines is presented. It is based on the harmfulness of typical defects able to generate PD and, hence, on the capability of the detection system (sensor, filters, PD detector, software) to provide efficient noise rejection and/or noise and PD source identification. The output, that is, the global health index, is thought to be helpful to support maintenance manager decisions about the actions which may be needed to keep reliability of a rotating machine at the desired level, and also to evaluate in terms of cost/effectiveness the potential maintenance actions.