Torque Speed Characteristic of an Induction Motor

Torque Speed Characteristic is the curve plotted between the torque and the speed of the induction motor. As we have already discussed about the torque of the induction motor in the topic Torque Equation of an Induction motor.

The equation of the torque is given as shown below.


At the maximum torque, the speed of the rotor is given by the equation shown below.


The curve below shows the Torque Speed Characteristic.

Torque Speed Characteristic of an induction motor

The maximum torque is independent of the rotor resistance. But the exact location of the maximum torque Ʈmax is dependent on it. Greater, the value of the R2, the greater is the value of the slip at which maximum torque occurs. As the rotor resistance increases, the pull out speed of the motor decreases. In this condition, the maximum torque remains constant.

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