On-line squirrel cage induction motors´ rotor mixed fault diagnosis approach based on spectrum analysis of instantaneous power

This paper deals with the common faults, such as broken rotor bar and eccentricity in induction motors. In order to overcome the shortage of broken rotor bars´ characteristic components being submerged by the fundamental one in the spectrum of the stator line current, instantaneous power of the motor is used as the quantity to be monitored in our work. Theoretical analysis indicates that the spectrum of AC level of the spectrum of the instantaneous power is clear from any component at the fundamental supply frequency, and the fault characteristics can be highlighted, which is effective to the separation of mixed faults and the quantification of the fault extent. Experimental results have demonstrated the effectiveness of the proposed technique.