Answer to Question #340904 in Electrical Engineering for Hope

Question

In a certain eight-pole, 50 Hz three-phase induction motor, the rotor resistance per phase is 0.04 Ω and the maximum torque occurs at a speed of 645 revolutions per minute (rpm). Assuming that the air-gap flux is constant at all loads, determine the torque developed as a percentage of maximum torque:

(a) at starting (8.0 marks) and  

(b) when the slip is 3 per cent (5.0 marks).                                           

Hint: Some derivation is necessary and reasonable approximations/assumptions will have to be made in order to solve this problem.