Critical Appraisal of Mcsa to Diagnose Short Circuited Turns in LV and HV Stator Windings and Faults in Roller Element Bearings in SCIMS

The measurement of displacement of the rotating shaft relative to the fixed bearing shells via displacement probes in the bearing housings and supported by shaft orbital plots is a well‐proven vibration analysis technique that can detect the problems, such as bearing wear, mechanical rotor unbalance, misalignment, and oilwhirl/whip in these bearings. Roller element bearings are predominately used in low voltage (LV) squirrel cage induction motors (SCIMs) and provided the bearing housings can be accessed, then vibration monitoring is universally applied to detect bearing defects via vibration spectrum analysis (VSA). Transient voltage surges due to lightning strikes or vacuum circuit breakers causing transient voltage surges at the terminals of high voltage (HV) SCIMs can break down the inter‐turn insulation. This causes short circuits between turns and very high currents flow, which subsequently cause breakdown of the ground wall insulation.