Measuring and evaluating methods for on-line induction motor diagnosis

In the paper a general problematic of induction motor diagnostics based on phase currents and vibration measurement is introduced. Static faults cause the increase of diagnostic symptoms, dynamic faults cause modulation. The envelope analysis of modulated signals for the dynamic faults using Hubert transform and Park transform are introduced together with the analysis of static stator faults. Using Park transform, the 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 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.