Question

For a given dc machine it is advised to use the dummy windings for a stable operation. But if it has be replaced as it unused component in the machine, then we must _________

(a) S/P/2 should not be an integer

(b) S/P/2 should be integer

(c) S/P should be integer

(d) S/P should not be an integer

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

Origin of the question is Armature Windings in chapter Armature Windings of Electrical Machines

Answer 1

The correct choice is (a) S/P/2 should not be an integer

Best explanation: If slots per pole pair is not integer than all the winding will be completed without adding any dummy coil.