Question

If it is desired to approximate the efficiency of an induction motor operating at slip ‘s’, then its efficiency is given by?

(a) 1-s/1+s

(b) 1/1+s

(c) s/s+1

(d) s/1-s

I have been asked this question in homework.

My question is from Equivalent Circuit in section Induction Machines of Electrical Machines

Answer 1

Right choice is (a) 1-s/1+s

The best I can explain: Approximately efficiency is given as 1-s/1+s for an IM.