Relationship between multi-broken-bar position and faulty feature on squirrel cage induction motor

The extended synthetic vector method was applied to derive an easy-solved mathematic model for the rotor-broken-bar squirrel-cage induction motor. Mathematical simulations performed on both transient and steady states reveal a close relationship between the faulty feature and parameter setting like broken-bar quantity, broken-bar relative position and load variation. Simulations and experimental results indicate that the maximum value for faulty feature appears when the broken-barpsilas relative position spacing in one pair-pole. The paper theoretically interpreted the phenomenon of no faulty feature appearance on the stator current if specially positioned broken-bars. Meanwhile, it revealed the characteristic of an across rotor two-end-ring phase voltage induced by the broken-bar. The study and investigation conclusions are directly applicable to induction motors online diagnosis and troubleshooting.