Question

In a resistance firing circuit the firing angle

(a) cannot be greater than 120°

(b) cannot be greater than 90°

(c) cannot be greater than 180°

(d) cannot be greater than 160°

The question was posed to me during a job interview.

The origin of the question is Firing Circuits-2 topic in division Other Circuits of Power Electronics

Answer 1

The correct choice is (b) cannot be greater than 90°

To elaborate: The R firing circuits cannot be used for alpha greater than 90 degrees.