Question

Spacing between the brushes for a 4-pole machine in terms of commutator segments is equal to 6. What will be the number of armature slots?

(a) 48

(b) 3

(c) 24

(d) 6

I had been asked this question during an interview.

This is a very interesting question from Brushes and Commutator Assembly topic in chapter DC Machines of DC Machines

Answer 1

Right option is (c) 24

The explanation: The spacing between adjacent brushes in terms of the commutator segment which is also equal to armature slots is ratio of number of commutator segments with poles for a given DC machine.

C= P*Spacing= 4*6= 24.