Question

The choice of average coil voltage determines the minimum number of commutator segments for its design.

(a) True

(b) False

The question was posed to me at a job interview.

My question is taken from Ways to Reduce Effects of Armature Reaction topic in portion Armature Reaction of DC Machines

Answer 1

The correct answer is (a) True

To elaborate: The maximum allowable voltage between adjacent segments is 30–40 V, limiting the average voltage between them to much less than this figure. The choice of the average coil voltage determines the minimum number of commutator segments for its design, to avoid any flashover and ultimately short circuit.