ABSTRACT Stator inter‐turn and ground faults in medium‐ and high‐voltage (MV/HV) motors often require full stator rewinding, causing long outages and high costs. This paper proposes a symmetry‐restoration‐based temporary reconstruction approach that allows continued operation with damaged stator coils. Instead of isolating only the faulty coil, which creates electromagnetic imbalance, the proposed pole‐pair‐based approach simultaneously disconnects the defective coil and its geometrically corresponding coils in other phases and pole pairs, preserving three‐phase current symmetry and a balanced rotating magnetic field. Finite‐element analysis (FEA) evaluates stator currents, rotor end‐ring currents, torque, and induced voltages in isolated coils. Results show that the current increase caused by coil removal can be compensated by a slight speed increase and controlled load reduction, restoring currents close to healthy conditions with moderate power derating. Induced voltages in disconnected coils remain well below insulation limits. The approach is validated through field application on two 1100 kW, 6.6 kV motors in a thermal power plant, which operated stably for over seven months under supervised reduced‐load conditions. Both simulations and on‐site measurements confirm acceptable electrical, thermal, and vibration behavior. Overall, the proposed pole‐pair symmetry restoration technique offers a practical, time‐efficient, and cost‐effective interim solution to maintain production continuity before permanent stator rewinding.
Taheripour et al. (Thu,) studied this question.