Inter-Turn Fault Detection of Induction Motors Using End-Shield Leakage Fluxes

In this article, a non-invasive online technique to detect inter-turn stator winding fault of induction motors using end-shield leakage fluxes is proposed. The fault indicator is based on the fundamental component of the summation of the leakage fluxes which are spatially separated by an angle of 360°/number of the poles. Theoretical analysis using the analytical and finite element models revealed that the proposed fault indicator is independent of number of poles and location of the fault in any of the coils of the stator windings. Both theoretical analysis and experimental validation on a 10 hp induction motor showed that the proposed anomaly indicator is directly proportional to the fault severity level. A comparative study with various non-invasive, terminal measurements-based online techniques reveals that the proposed methodology is the most sensitive technique with an additional advantage of more than 92% reduction in the sensor cost for a 4-pole, 10 hp induction motor. Real-time evaluation of the proposed anomaly indicator with the prototype Motor Winding Monitoring Device (MWMD) shows that even under intermittent conditions, as small as 1-turn fault (0.5%) can be detected within 150 ms without any false alarms.