Question

The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is zero at __________

(a) 0.45 lagging

(b) 0.45 leading

(c) 0.9 lagging

(d) 0.9 leading

This question was addressed to me during an interview for a job.

My question is from Transformer Losses and Efficiency topic in chapter Transformers of Electrical Machines

Answer 1

The correct answer is (c) 0.9 lagging

Easiest explanation: Z = 4.47; cosθ = percentage x/percentage z = 4/4.47 = 0.89.