Question

For the below given circuit, α = 60°. T2 will start conduction at ωt = __________ Assume the inductor L value to be negligible.

(a) 60°

(b) 120°

(c) 90°

(d) 150°

This question was posed to me in an online interview.

My doubt stems from Three Phase Converters-2 in division Converters of Power Electronics

Answer 1

Right option is (d) 150°

Easy explanation: sion: Assuming the phase sequence is R-Y-B. T1 would start conducting at 30+60 = 90°, T2 at 90+210/2 = 150°. This is because after T1, T3 would conduct from the upper group, as T2 belongs to the lower group it will start to conduct exactly between T1 and T3 i.e. between 90 and 210(90+120) which is 150°.