Question

For a single phase transformer operating at normal operating conditions has useful flux of 1 Wb. If the machine is loaded at 0.8 p.f., then its mutual flux __________

(a) may decrease to 0.98 Wb

(b) remains constant

(c) may increase 1.02 Wb

(d) may decrease to 0.8 Wb

I have been asked this question by my school principal while I was bunking the class.

The question is from Equivalent Circuit of Transformer in section Transformers of Electrical Machines

Answer 1

The correct answer is (a) may decrease to 0.98 Wb

The explanation: The mutual flux will decrease by a very small amount.