Question

From the above graph of the core losses per cycle is, the eddy losses per phase for a transformer at a operating frequency of 40 Hz is?

(a) 15 W

(b) 20W

(c) 35W

(d) 32W

The question was asked at a job interview.

This intriguing question originated from Transformer Losses and Efficiency in division Transformers of Electrical Machines

Answer 1

The correct choice is (a) 15 W

The explanation: Pe = k2*f^2;

           Using the slope of the line, (k2)*50 = 0.8 – 0.5 = 0.3

           (k2) = 0.006

Pe = 50*50*0.006 = 15 W.