Induction Motors Torque Equation; Torque equation

Torque equation for the Induction motor is as given below:-

As we see from the above that Torque equation is Directly proportional to square of the voltage.

Factors affecting the speed-torque characteristics of an Induction motor : The speed-torque characteristics are affected by various factors like applied voltage, R₂’ and frequency.

(a) Applied voltage : We know that T µ V². Thus not only the stationary torque but also the torque under running conditions changes with change in supply voltage.


(b) Supply frequency : The major effect of change in supply frequency is on motor speed. The starting torque is reduced with increase in frequency.

(c) Rotor resistance : The maximum torque produced does not depend on R₂’. However, with increase in R₂’, the starting torque increases. The slip at which T_max is reached increases too which means that T_max is obtained at lower motor speeds.