Rotor Faults Detection in Squirrel-cage Induction Motors by Current Signature Analysis

The condition monitoring of the electrical machines can significantly reduce the costs of maintenance by allowing the early detection of faults, which could be expensive to repair. In this paper some results on non-invasive detection of broken rotor bars in squirrel-cage induction motors are presented. The applied method is the so-called motor current signature analysis (MCSA) which utilises the results of spectral analysis of the stator current. The diagnosis procedure was performed by using virtual instruments (VIs). The significant presence of some well-defined sideband frequencies in the harmonic spectrum of the measured line current clearly indicates the rotor faults of the induction machine. The theoretical basis of this method was proved by laboratory tests.