Faults diagnosis of three-phase induction motors using envelope analysis

An induction motor is an electromechanical device and mutual influence leads to signal modulation. In the paper the envelope analysis for the dynamic faults using Hilbert transform and Park transform are introduced together with the analysis of static stator faults. Conversion coefficients for real faults to stator to Park´s vector magnitude are introduced. The assessment of motor state and fault factors are based on relative factors by means of modulation indexes m, associated with the fault frequencies and by means of the relative stator fault coefficient k_p. The theoretical results were practically verified on motors with purposefully made rotor and stator faults and compared with MATLAB model results.