Question

It is possible to attain maximum efficiency in a transformer when the ______

(a) core losses are equal to rated full load copper losses

(b) core losses are more than rated full load copper losses

(c) core losses and full load copper losses are constant

(d) copper loss also becomes constant

I have been asked this question in examination.

This interesting question is from Transformer Losses and Efficiency topic in section Transformers of Electrical Machines

Answer 1

Right option is (a) core losses are equal to rated full load copper losses

Easy explanation: Maximum efficiency is achieved at the condition when fixed core losses and copper losses at rated condition are equal.