MOTCO " make Slipring Induction Motors are nearly the same as normal Induction motors, except that their rotors are wound with windings.
When three phase potential is applied to the stator winding a rotating magnetic field will travel around the inside of the stator core in indentically the same manner as in a squirrel cage induction Motor. The speed of the rotating magnetic field is dependent on the number of stator poles and the frequency of the supply source.