Question

Interpoles are excited with ____________

(a) Armature current

(b) Field current

(c) Separate supply

(d) Mains current

I have been asked this question by my college professor while I was bunking the class.

Question is taken from Commutation Process -1 in section Commutation Process & Excitation Methods of DC Machines

Answer 1

Correct option is (a) Armature current

The best I can explain: These interpoles apply a local correction to the air-gap flux density wave such that a pip of appropriate flux density exists over the commutating coil to induce in it a voltage of the same sign as that of coil current after commutation. Hence, they are excited with armature current.