Transient behaviour of a three-phase slip-ring induction machine following a short supply interruption

A coupled finite-element and circuits method has been described that can model the transient electrical and mechanical behaviour of slip-ring induction motors. The general technique is capable of modelling rotor and stator slotting effects and includes saturation of the magnetic circuit. A simple means of prediction the initial steady-state conditions of the motor has been outlined, resulting in a significant reduction in the overall solution time. The method has been used to demonstrate the transient behaviour of a slip-ring motor following disconnection from the supply. The effect of saturation on the steady-state full-load stator phase currents has also been demonstrated. The influence of the rotor currents following a disconnection up to two cycles of the supply has been shown to influence the initial negative torque normally present following a normal supply connection at speed