Broken Bar Fault Detection in IM Operating Under No-Load Condition

This paper presents a novel method for broken rotor bar detection in a squirrel-cage induction motor (IM). The proposed method applies a single-phase AC voltage as a test signal on motor terminals, resulting in a stator backward-rotating magnetic field. The field ultimately causes additional current components in the stator windings whose magnitudes depend on the broken bar fault severity, even if the motor is unloaded. This allows robust broken bar fault detection based only on standard motor current signature analysis (MCSA) technique. The proposed fault detection method is at first verified via simulations, using an IM model based on finite element analysis (FEA) and multiple coupled circuit approach (MCCA). The subsequent experimental investigations have shown good agreement with both theoretical predictions and simulation results.