Assessment of valve actuator motor rotor degradation by Fourier analysis of current waveform

A motor diagnostic system report is presented. It uses motor current waveform Fourier analysis to detect broken motor rotor bars or driven equipment defects. The test was conducted on a motor driven valve actuator. This, in turn, drove a dynamometer that measured actuator output torque. The motor was gradually degraded by open-circuiting rotor bars. The test confirmed the efficacy of the waveform analysis method for assessing motor rotor degradation. It also provided changes in waveform characteristic data as motor rotors are gradually degraded to failure