Comparative investigation of diagnostic media for induction motors: a case of rotor cage faults

Results of a comparative experimental investigation of various media for noninvasive diagnosis of rotor faults in induction motors are presented. Stator voltages and currents in an induction motor were measured, recorded, and employed for computation of the partial and total input powers and of the estimated torque. Waveforms of the current, partial powers and , total power, and estimated torque were subsequently analyzed using the Fast Fourier Transform. Several rotor cage faults of increasing severity were studied with various load levels. The partial input power was observed to exhibit the highest sensitivity to rotor faults. This medium is also the most reliable, as it includes a multiplicity of fault-induced spectral components.