Question

If T1, T2 are kept off and T3, T4 are having a firing angle of 180° each, then the output voltage is ____ if the turns ratio is 1:1

(a) Vs

(b) √2Vs

(c) 0

(d) 2Vs

The question was posed to me in examination.

I'd like to ask this question from Sequence Controller topic in section Voltage Controllers of Power Electronics

Answer 1

Right answer is (c) 0

The best I can explain: If T3 and T4 are fired at an angle of 180°, they are equivalent to an off switch, as they are fired and naturally commutated at the same time, hence they are never on.

Hence, as all the four SCRs are always off, the output voltage is zero.