Stator Winding Monitoring

Partial discharge tests can determine which motor and generator stator windings are experiencing insulation problems. A deteriorated winding has a PD activity which can be 30 times or more higher than a winding in good condition. This great difference in PD activity enables even nonspecialized maintenance personnel to identify the few motors or generators in a company which need further investigation and/or maintenance. There are several advantages to on-line partial discharge tests. Machines in good condition require less attention. The overall effect is lower maintenance costs. After implementing on-line partial discharge tests, as well as other monitoring such as flux probing or current harmonic analysis and improved temperature sensing, companies can often confidently extend the outage between major machine inspections. This saves on outage costs and reduces the risk of a stator fault due to human error during maintenance. Finally, on older machines, if there has been no increase in partial discharge activity over time, then the life of the stator winding can be confidently extended, saving a considerable capital expenditure.