Available Start Torque

[hncelectrical]

General question. Why is the available start torque of a three phase, 4 pole induction motor less than the peak torque that a motor can produce?

 

Thanks,

 

Peter

[marke]

Hello Peter

 

Welcome to the forum.

 

The torque developed by the induction motor is a function of the slip and the rotor design.

 

If you use a high resistance rotor, the maximum torque will occur at high slip and the start torque will be the maximum torque, but with this design of rotor, the full load slip is high and so the efficiency is low.

In order to improve the efficiency and minimise the full load slip, the rotor resistance is low and this results in a torque peak close to full load speed.

 

Best regards,

Mark.