Influence of Rotor Position on Frequency Response of Induction Motor

The Frequency response analysis is a widely used tool to diagnose mechanical fault(s) in power transformers. The induction motor operates based on the same principle as the transformers, especially windings are inductively coupled. Except for a few constructional differences between transformers and induction motors, there is a high possibility to consider the frequency response analysis on induction motor for the mechanical fault detection. Here, variation in frequency response of induction motor due to rotor position is studied by employing various terminal connections. These connections are compared with among themselves in terms percentage impedance deviation and the best is suggested for frequency response analysis of induction motor to avoid rotor position dependency. A connection arrangement is proposed which makes the deviation in frequency response for different position less than or equal to 2%.