GB190924269A - Improvements in or relating to the Driving and Operation of Electric Frequency Transformers having Commutators. - Google Patents

Abstract

24,269. Siemens Bros. Dynamo Works, [Siemens-Schuckertwerke]. Oct. 22. Frequency, changing.-A polyphase frequencytransformer with commutator and slip-rings is driven by an induction motor, the commutator brushes are connected to the slip-rings of the motor, and the slip-rings of the transformer are connected to the stator winding of the motor or vice versa. The slip-rings of the primary of the frequency - transformer f are shown connected to the secondaries of the transformer t, the primaries of which are connected to the primary mains u. These mains also supply the stator winding of the motor m that drives the transformer f. The slip-rings of the motor m and the commutator brushes of the transformer f are connected together to the secondary mains a<1>. The two sets of mains may be used to supply a motor, the mains a being connected to the stator winding and the mains a<1> to the rotor slip-rings. The speed of the motor is varied by variation of the pressure-ratio of the transformer t. The transformer f may be provided with a fly-wheel to compensate for variations in load on the motor. The position of the commutator brushes may be altered in a manner depending upon the current frequency in the mains a<1> or upon the adjustment of the transformer t. An adjustable phase-transformer may be connected in the primary or secondary circuits of the motor m or transformer f. The stator of the motor m may be arranged to rotate through an angle according to the frequency in the mains a'. The working motor may be started with a large torque by running the motor m and transformer f with the fly-wheel at such a speed that the frequency in the mains a<1> is the same as that in the mains a. The working motor is then switched in, and the transformer t is regulated to cause the fly-wheel to drive the motor m as a generator to assist in starting the working motor.