Question

Calculate the conduction angle in purely inductive load if the firing angle is 165°.

(a) 78°

(b) 55°

(c) 30°

(d) 19°

The question was posed to me at a job interview.

Query is from Solid-State Switching Circuits in section Introduction to Solid-State Switching Circuits of Electric Drives

Answer 1

Right answer is (c) 30°

Explanation: The conduction angle in the purely inductive load is β-α=2(π-∝)=2(180°-165°)=30°. The conduction angle is the angle for which the current exists in the circuit. The average value of the voltage in a purely inductive load is zero.