Effect of change in Supply Voltage on Torque and Slip

Let’s say, ‘s’ is the slip of the running motor. Cited formula below represents the value of Torque when it acts on the rotor:

At the standstill position in rotor with induced electromotive force (e.m.f), the value of torque with

Considering k’ is added constant

With the statement that slip ‘s’ is very low at full load condition, it will be okay to state that S2X2 will be neglected as compared to R22, therefore value of torque will be:

  sV²

The torque changes even on the running condition as the supply voltage is altered or changed. Let’s consider both the conditions:

• When supply voltage is decreased, torque is also reduced under running condition
• With increase in supply voltage, torque is also greater than before

But it is important to maintain the same torque in running condition which is possible when the slip increases or the speed decreases.