Recommended On-Site Smart Assessment Techniques For Stator Winding Of Large Rotating Machines

Large rotating machines stator winding insulation system degrades over time due to presence of several types of stresses. The level of degradation depends upon the application, environment, and machines service life. Several types of diagnostic tests are defined in Industry standards that can be performed to assess the winding insulation condition. It is critical to initiate assessment by conducting a visual inspection as it provides evidence of the physical condition of various components. The visual inspection also helps to understand what types of stresses windings have been exposed while under operation, e.g. electrical degradation associated with partial discharges, endwinding vibration, surface discoloration due to thermal excursions or deposit of surface contamination present in the environment. In this paper an on-site smart assessment technique using combination of different Industry standards have been proposed. In addition, based on several years of experience and lessons learned, new assessment protocols for different machine ratings are outlined for effective heath assessment along with predictive maintenance.