Question

A three-phase three pulse type controlled converter is constructed using 3 SCR devices. The circuit is supplying an R load with α < 30°. As such, each SCR device would conduct for

(a) 60° each cycle

(b) 120° each cycle

(c) 180° each cycle

(d) 360° each cycle

I had been asked this question in an online interview.

Asked question is from Three Phase Converters-1 topic in section Converters of Power Electronics

Answer 1

Right option is (b) 120° each cycle

Easiest explanation: Each conduct for 120° per cycle is the firing angle is less than 30°. 120 x 3 =  360°.