Rotor Faults Diagnosis for Induction Motors Considering Effects of the Load and Inertia

This paper concerns following two issues that are critical to the reliable diagnosis of rotor faults of induction motors. The first is to define a fault severity index that is independent of load level and mechanical inertia; and the second is how to discriminate between rotor faults and periodic load fluctuation. Based on the detailed analysis of the relationships between current sideband components at frequencies (1±2s)fs (s is slip and fs is supply frequency) due to rotor faults or load fluctuation, a new fault severity index that is independent of load level and mechanical inertia is given, and then a method to reliably discriminate between rotor faults and load fluctuation is presented. Experimental results from a 4kW induction motor demonstrate the validity of the proposed method.