What is the use of interpoles in dc machine?

Answer 1

push push............!!!

Answer 2

interpoles are similar to main field poles and are located on the yoke between the main field poles.they have windings in series with the armature winding.interpoles have the function of reducing the armature reaction effect in the commutating zone.they eliminate the need to shift the brush assembly.

Answer 3

Interpoles serves two important role in DC machie.
1)It nutralise  reactance voltage produced in shote circuite coil undergoing commutation resulting good commutation.
2)It nutralises cross magmetising effect of arature reaction.
  
Interpoles are situated between main poles and are wound for few turn of thick copper wire connected in series with armature & so carring full armature current . It,s polarity are similar to that of mail poles.So reversing emf induced in coil undegoing commutation which nutralises reactance voltafe of that short circuite coil.
Also these are pleaced in such a way that they nutralises cross magnetising effect of armature reaction.

In both cases the action are automatic i.e as load current increases, reactance voltage increases which in tuns increases the reversing emf so nutralising nutralises reactance voltage.
And as load current increases cross magmetising amp turns increases so counter flux also increases which complitly nutalises cress magnetising effect.