The purpose of interpoles in DC machines is to nullify

• A. The demagnetizing effect of armature mmf
• B. The reactance voltage
• C. Both the cross-magnetizing mmf and the reactance voltage
• D. The cross-magnetizing effect of armature mmf

Answer: (C)

interpoles is widely use to improve commutation
place between main poles fitted to yoke
functions:
to neutralize armature mmf in commutating zone
to produce some flux in commutating zone