Question

In a DC generator, the effect of armature reaction on the main pole flux is to _________

(a) Reduce it

(b) Distort it

(c) Reverse it

(d) Reduce and distort it

I got this question during an interview.

The doubt is from Armature Reaction -1 in chapter Armature Reaction of DC Machines

Answer 1

Correct option is (d) Reduce and distort it

To explain I would say: When non-zero load current is passed through the armature winding, the distributed armature winding produces its own mmf known as armature reaction. According to its nature cross-magnetizing and demagnetizing, it will distort or reduce the main flux distribution.