Distribution of inter-bar currents in cage induction machines

This paper examines the influence of interbar currents in uninsulated cage rotors of induction motors. A previous paper by the authors developed a model for including interbar currents that reduces to a simple modification to the conventional chain equivalent circuit. This model is used to demonstrate that a low value of interbar resistance tends to undo the rotor skew and as a result the starting torque is particularly sensitive to the value of the interbar resistance. Harmonic torques can be enhanced by low values of interbar resistance. The paper investigates the distribution of interbar currents around the rotor and shows that the end-ring influences the distribution of interbar currents. The model is used to demonstrate that the interbar current path can allow a motor to operate with the end-rings removed or faulted.