Question

A 3-phase slip ring IM is has its copper bars changed by the aluminium bars in the machine. With the above change ___________

(a) starting torque remains same

(b) starting torque increase

(c) starting torque decrease

(d) maximum torque increase

The question was asked during an interview for a job.

This intriguing question originated from Starting of Polyphase Induction Motors-II topic in portion Starting of Induction Motors of Electrical Machines

Answer 1

The correct answer is (a) starting torque remains same

To explain I would say: Resistance increase, so the starting torque increase.