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 diagnostics of rotor faults in induction motors are presented. Stator voltage and current in an induction motor were recorded and employed for computation of the partial and total input powers, and the estimated torque. Waveforms of the current, partial powers p_ab and p_cb, total power, and estimated torque were next subjected to the fast Fourier transformation. Rotor cage faults of increasing severity were imposed, and the motor was operated with various load levels. The partial input power p_cb referred to its DC component turned out to have the highest sensitivity to faults. This medium is also most reliable, owing to the multiplicity of fault-induced spectral components