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
due to fractional pitch EMF can be approximately made into sine wave losses due to harmonics reduced saving in conductor material mechanical strength of coil is increased.
slip ring motor have high starting torque compare to squirrel cage motor and have good speed control also have high over loading capacity, smooth acceleration under heavy loads.
EXAMIANS