Electronics and Communication Engineering - Power Electronics - Discussion


A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45°, the speed is likely to be

[A]. about 350 rpm
[B]. about 250 rpm
[C]. about 175 rpm
[D]. about 125 rpm

Answer: Option D


Average output voltage ∝ cos a and therefore reduced to 0.707 of the value for a = 0. Speed is nearly proportional to voltage.

Spt said: (Dec 24, 2014)  
0.707 of 500 rpm is nearly 350 rpm.

Sid said: (Jul 14, 2017)  
Yes, A is the answer.

Namita said: (Jul 24, 2019)  
A is the right answer. I also agree.

Prakash said: (Sep 11, 2020)  
Option A is the correct answer.

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