The implications of winding faults in induction motor drives

This paper examines the effects winding faults upon the operation of induction motors, both when directly line fed and when vector controlled. The effects of different numbers of shorted turns in one coil of the stator winding upon the operation of 3-phase and 5-phase, induction-motor drives will be examined. A simple thermal model of the coil is used to examine the duration the fault can be allowed to exist before there is further degradation of the insulation. Simulation results given by a Dynamic Mesh Reluctance Model of the machine incorporate saturation and slotting effects. Shorting small numbers of turns gives very little time before further failures could occur. Shorts of large numbers of turns change machine flux levels, saturation and torque constant. Part functionality following a winding fault might aid controlled, drive shutdown or provide an idling mode in multi-actuator, aircraft, flight-actuation-systems. This could be particularly helpful with electromechanical actuators.