APPLICATION OF PARTIAL DISCHARGE TESTING TO MOTOR AND GENERATOR STATOR WINDING MAINTENANCE

Deterioration of stator winding insulation continues to be one of the predominant-causes of large motor and generator failures. Over the pas t several years, practical methods have been developed for measuring t he partial discharge activity in the high voltage insulation of stator windings, since partial discharges are a symptom of most of the insul ation failure mechanisms in motors and generators rated 4 kV or more. The turbine generator analyzer (TGA) test has now been specifically de veloped to enable industrial plant staff to reliably perform a partial discharge test on operating motors and turbine generators. This paper presents several case studies of the use of these new partial dischar ge test technologies on rotating machines. Test results show that mach ines with deteriorated windings have a Partial discharge activity al l east 30 times higher than good windings. The availability of these tes t methods enables plant staff to economically and reliably plan stator winding maintenance, avoid unexpected failures and often extend the t ime between major maintenance outages.