Question

For a wave wounded machine number of brushes for small, large machines respectively is ________   _________

(a) 2, 2

(b) 4, 2

(c) 2, P

(d) Both values depend on the given conditions

This question was posed to me during an interview for a job.

The above asked question is from Wave Winding in portion Armature Windings of DC Machines

Answer 1

Correct choice is (c) 2, P

The best explanation: For a small wave wounded machine number of parallel paths are 2, thus 2 brushes are used. For a large machine total number of brushes is equal to the total number of poles. The spacing between adjacent brushes is C/P commutator segments.