Three Phase AC Shunt Commutator Motor:
The connection diagram of a three phase ac shunt commutator motor is shown in Fig. 1.37. In this motor, the stator is connected directly to the supply while the rotor brushes are connected to the supply through a transformer.
Speed variation is obtained by changing the tapping points on the transformer. It is to be noted here that brushes are fixed in position in the motor of this type. Such a motor provides more or less constant speed at all loads, for a given tapping on the transformer.