GB282828A - Improvements in or relating to dynamo electric machines - Google Patents

Abstract

282,828. International General Electric Co., Inc., (Assignees of Allgemeine Elektricitõts-Ges.). Dec. 30, 1926, [Convention date]. Void [Published under Sect. 91 of the Acts]. Rotary transformers; windings; exciting; commutating windings. - A continuous-current dynamo-electric machine having two separate commutator windings or a single armature is provided with main and regulating field poles, in such a manner that the voltage in the brush axis of one commutator is due to the sum of the main and regulating fluxes, and in the other brush axis to the difference, so that the ratio of the commutator voltages may be varied. A rotary transformer, Figs. 1 and 2, has main poles N, S carrying a winding a connected across the supply mains and a compounding winding b, and regulating poles N<1>, S<1> having a winding c with a variable resistance d in series. The voltage across the motor brushes m<1>, m<2> is proportional to the difference of the main and regulating fluxes whereas the voltage across the generator brushes g<1>, g<2> is proportional to the sum. To obtain a greater range of secondary voltage regulation, for example, in starting railway motors, the current through the winding c may be reversible. If it is desired to compensate for the secondary voltage drop the regulating pole winding may be connected in series with the secondary load. Alternatively if a constant secondary voltage is required with a fluctuating supply voltage, for example for lighting systems or railway installations, the winding on the regulating poles may be connected across the supply mains or across the motor brushes. In this case the auxiliary poles are given a polarity opposite to that shown in Fig. 1, and are only slightly saturated whereas the main poles are highly saturated. The machine may be used as a threewire generator or as a balancing transformer in a three-wire system, the regulating pole winding being in series with the middle wire. If the main and regulating poles are located in axially displaced planes, the armature coils of both windings are bent as shown in Fig. 7, or, as shown in Fig. 8, the coils of one winding are twisted in the form of the numeral 8. Commutating poles may be employed excited partly from the. load current and partly from the current in the regulating pole winding.