On the transient short circuit torque expression of induction machines

In this paper the transient electromagnetic torque expressions of an induction machine have been deduced and analyzed in the case of a three-phase short circuit of the supply network. Starting from the precise mathematical expressions for stator and rotor currents in the short circuit transient, the expressions of the electromagnetic torque have been established. Two damping components with the same low time constant have been highlighted: a sinusoidal one and a constant one. Due to the complicated form of the final expressions, simplified formulas for parameter expressions have been deduced in order to calculate the maximum torque value. Conclusions regarding the nature and the duration of the transient electromagnetic torque have been drawn.