Question

What is the value of Yb for a lap winding with a 4-pole, 12-slot armature with two coil sides/slot. Assume single-turns coils.

(a) 3

(b) 5

(c) 7

(d) 9

I had been asked this question at a job interview.

I want to ask this question from Lap Winding topic in portion Armature Windings of DC Machines

Answer 1

Correct answer is (c) 7

Easy explanation: Coil span is defined as a ratio of number of slots in the armature winding which are also equal to the number of commutator segments to the number of poles. Here, Slots in the armature winding= 12, Number of poles= 4.

YCS= 12/4= 3.

Yb = 2YCS +1= 7.