Comparative investigation of diagnostic media for induction motors: A caseof rotor cage faults

Results of a comparative experimental investigation of various media for no ninvasive diagnosis of rotor faults in induction motors are presented. Stat or 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 p(AB) and PCB, t otal power, and estimated torque were subsequently analyzed using the Fast Fourier Transform, Several rotor cage faults of increasing severity were st udied with various load levels. The partial input power p(CB) 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 com ponents.