Question

In AC voltage controllers the

(a) variable ac with fixed frequency is obtained

(b) variable ac with variable frequency is obtained

(c) variable dc with fixed frequency is obtained

(d) variable dc with variable frequency is obtained

I had been asked this question during an interview for a job.

The doubt is from AC Voltage Controllers-1 in chapter Voltage Controllers of Power Electronics

Answer 1

Correct choice is (a) variable ac with fixed frequency is obtained

To explain: Voltage controllers convert the fixed ac voltage to variable ac by changing the values of the firing angle. The available ac obtained has the same fixed frequency as the input ac.