The Two-Speed Cascade Induction Motor

The general conditions of operation of two motors in direct and differential cascade are considered, with special reference to the possibility of the set running at a speed near the synchronous speed of the primary machine, while still connected in cascade. Hunt´s cascade motor is next described. The theory of the superposition of two fields in one magnetic circuit is given, and vector diagrams are drawn of the M.M.F. to be produced by the rotor windings at each point. The superposition of two currents of different frequency in the stator windings is next dealt with, and an account is given of the experimental work carried out to verify this theory, by means of oscillograph records of the currents flowing in the various coils of the stator windings of the motor tested.