Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

 the interpoles produce additional flux to augment the developed torque
 a counter-emf is induced in the coil undergoing commutation
 the inequality of air-gap flux on the top and bottom halves of the armature is removed
 the flux waveform is improved with reduction in harmonics

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
The synchronous reactance( Xs) is the

 combined reactance due to armature reaction and leakage flux
 reactance due to leakage flux
 reactance due to armature reaction of the machine
 reactance either due to armature reaction or leakage flux

ANSWER DOWNLOAD EXAMIANS APP