Motor Current Signature Analysis to Detect Static Eccentricity in Case of 300 kW Induction Motor

Abstract

In this paper the current spectrums of a five pole-pairs, 300 kW, squirrel cage induction motor were calculated for the cases of full symmetry and static eccentricity.

The calculations account for variable inductances affected by slotting and eccentricity. The calculations were followed by Fourier analysis of the stator currents in steady state operation.

The paper includes stator current spectrums affected by different degrees of static eccentricity to demonstrate the effect of static eccentricity on the stator current spectrum and to predict the harmonics related to this ailment. The motor under investigation represents a special example because its stator current spectrum includes more than one slot harmonic that is, supposedly, due to the unique configuration of the stator winding and rather high number of pole pairs (p=5). Zooms of the current spectrums, around the 50 Hz fundamental harmonic as well as of each slot harmonic zone, are included. In addition the paper includes the stator current spectrum that referred to the real measured currents.