GB190904652A - Improvements in and relating to Single Phase Alternating Current Electric Commutator Motors. - Google Patents

Abstract

4652. Maschinenfabrik Oerlikon. Feb. 26,1908, [Convention date]. Alternating-current commutator machines ; commutating-poles.-In the regulation of alternating- current commutator motors, having commutating- pole windings excited by a voltage which is reduced as the speed of the motor increases, the motor is supplied with current from a transformer having a secondary winding divided up into large and small sections, and the connexions are so arranged that the electromotive force of a large section is used to increase or reduce the electromotive force that excites the commutating-field. In the arrangement shown in Fig. 1, the transformer 1 has a primary winding 2 and a secondary winding consisting of the coils 3 ... 6, which may be connected to the motor 7 by switches 8 ... 12. The commutating-winding 16 of the motor is connected to a special transformer 13 through an auxiliary transformer 15. At starting, the switches 10, 11 only are closed. The motor is then fed from the coil 5, and the winding 16 is fed from the transformer 13 acting in conjunction with the coil 6. The switches 9, 8 are then successively closed after opening switches 10, 9. The next controlling position consists in opening the switches 8,11 and then closing the switches 10, 12, whereupon the motor is fed from the coils 5, 6, while the winding 16 is supplied only from the transformer 13. The last controlling positions are obtained by closing the switches 9, 8 after opening the switches 10, 9, as before. In a modification, the transformer 13 is replaced by an extra secondary coil on the transformer 1, and the coil 6 is divided into two parts, which may assist or oppose the extra secondary coil communicating with the commutating-winding. One example of this arrangement is shown in Fig. 3, in which the extra coil 17 is connected directly to the winding 16, and the coil 6 is tapped at an intermediate point.