Rotor fault diagnosis using external search coils voltage analysis

A high precision search coil is used for monitoring of the broken bars in the squirrel cage induction machines. The searches coils are implemented in a finite element model witch describe the real behavior of the machine. The external search coils are fixed on Ox and Oy axis for analyzing the leakage flux in the outer region. The method offer a number of advantages including compact size of the sensor, great accuracy, high bandwidth, low cost, and it is applicable even for already fabricated electric machine. The performance of the search coils is evaluated by some default degrees. The Ox search coils voltage spectral analysis has also been performed. All simulations cases were performed for the proposed FE model of 5,5kW, 400 V, 1455 r/min induction motor, for the case of a healthy rotor and for the cases with different deliberately damaged rotor.