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Oct. 27, 1936. G. M. PESTARIN 2,059,024 ROTARY TRANSFORMER Filed June 24, 1933 Giuseppe M. Pestarini By 2sezza a2zesATTORNEy. Patented Oct. 27, 1936 2,059,024 UNITED STATES PATENT OFFICE 2,059,024 ROTARY TRANSFORMER Giuseppe Massimo Pestarini, Sheffield, England Application June 24, 1933, Serial No. 67,521 In Great Britain July 29, 1932 3 Claims. (C. 171-123) This invention relates to rotary transformers for direct electric currents and to electric motor . ated with one commutator and One or both of equipments operated in connection therewith. the secondary brushes being associated with the More particularly the invention relates to rotary other commutator in quadrature electrical rela transformers of the type known as and herein tion to the primary brush set. The two commu after called metadyne transformers which are tators are connected to a single winding in which machines designed to transform a current Sup both the primary and Secondary currents circu plied thereto at a fixed voltage and variable am late. As the primary brushes are separated by a peres into a current at constant amperes and considerable distance from the secondary brushes 0 variable voltage. A metadyne transformer com liability to flash-over between these pairs of prises in general a rotor provided With Windings brushes is substantially eliminated. If a meta 10 and a commutator somewhat similar to the ar dyne transformer is designed as a one-cycle ma mature of a direct current dynamo electric ma chine, that is to say the same disposition of elec chine. Four brushes are arranged to make con trical elements and magnetic elements occurs s tact with the commutator, two of which are used Only Once in progressing through one complete for the primary circuit and two With the Sec turn round the rotor in the air gap between the 5 Ondary circuit arranged in quadrature electrical rotor and stator, the primary and secondary relation with the primary brushes, The rotor is brushes will be located at opposite ends of dif rotated at a constant speed in the magnetic field ferent diameters of the machine at right angles 20 which is due to the currents circulating in the to each other, thus further eliminating the lia rotor windings, a stator being provided which af bility to flash-over. With a multicycle machine 20 fords a return path of low magnetic resistance the diameters at the respective ends of which the for the flux which is set up by the rotor currents. primary and secondary brushes are located will The stator is furnished with windings by which not be perpendicular and the brushes will not be 25 various magnetic fluxes can be obtained which located So far apart as in a one-cycle machine. combine with the magnetic fluxes due to the pri Otherwise the conditions are similar. The volt 25 mary and Secondary currents circulating in the age between two contiguous commutator seg regulator and thereby regulate the electro ments in a metadyne transformer is furthermore mechanical performance of the machine. For a leSS favourable to the occurrence of flash-overs 30 fuller description of metadyne transformers ref than is the case with an ordinary dynamo ma erence is directed to the specifications of French Chine. Such voltage between segments under 30 Patents No. 547,855, dated 25th February 1922, SGme conditions falls to zero, or may even be No. 623,438, dated 27th January 1926, and No. reversed. The commutators may be located at 637,946, dated 25th November 1926. opposite ends of the machine, or in some cases 35 A description of the general construction and flash guards may be provided on each commu operation of metadyne transformers, generators tator at the Zone of commutation of the brushes 35 and motors treated mathematically in consider Of the other commutator if desired. able detail will also be found in a paper entitled Where the rotor is provided with a single wind "Essuisse sur la Metadyne' by G. M. Pestarini ing and two commutators the primary brush in the Bulletin Scientifique A. I. M. No. 4 April which is connected to the high voltage terminal 1931 of l'Association des Ingénieurs Electriciens, of the Supply circuit may be associated with one 40 published by the Institut Electrotechnique commutator and the other brushes, namely the Montefiore, Liège. other primary brush and the brushes by which Metadyne transformers when operated at high current is conducted to and from the secondary 5 voltages, 1500 or 3000 volts for example, as com circuit, associated with the second commutator, monly employed in electric locomotives, are liable or in Some cases one of the secondary brushes 45 to Serious Sparking at the commutator segments may be aSSociated with the same commutator as which may produce flash-Overs and arcs from that with which the primary brush connected to brush to brush resulting in damage to the com the high voltage terminal of the supply is associ mutator and brushes, and the chief object of the ated. In these cases it is clear that no flash-over present invention is to provide improved con from the high voltage primary brush can reach 50 structions which will avoid this objection. any point immediately connected to earth. According to the invention a metadyne trans With metadyne transformers having two com former rotor is provided with two commutators, mutators as hereinabove described the load or One or both of the primary brushes being associ consumption devices in the secondary circuit may be arranged across the secondary brushes which 55 2 2,059,024 are then connected in what is commonly termed cated as being a motor 4, is in this figure shown in cross connection. a cross-connection. Where, however, the load is In Fig. 4 the arrangements of the metadyne such as to be readily divisible into two parts, for transformer are similar to those of Fig. 3 but the example where it comprises a plurality of motors load is shown as comprising two motors O and which can be readily divided into two groups, which are connected in figure-8 connection. one group may be connected between one primary In Fig. 5 the rotor f of the transformer is pro brush and one Secondary brush, and the other vided with a winding 20, and one primary brush group connected between the other primary brush 3 and one secondary brush 5 are shown as being and the remaining secondary brush, this is com associated with the commutator 8 while the re C 0. monly known as the figure-8 connection. When maining primary brush 4 and secondary brush 6 the rotor has only one winding the figure-8 con are associated with the commutator 9. The load nection can only be used if the load is divisible in this instance is shown as consisting of two into two substantially similar parts and it is pref motors O and , of which motor O is con erable to employ some series field windings on nected between the primary brush 3 and the sec 5 the motors in order to assist in maintaining stable ondary brush 5, the motor being connected conditions of the motors. between the primary brush 4 and the secondary In order that the invention may be clearly un brush 6. The sense of rotation is preferably the derstood it will now be described with reference one indicated by the arrow (counter-clockwise). to the accompanying drawing the figures of which With this disposition a flash-Over starting from 20 are electrical diagrams illustrating various meth the primary brush-Set associated with the high ods of carrying out the same in practice. voltage terminal cannot reach any other brush-set In all the figures the rotor of a neta dyne trans unless it makes 3A of a complete revolution which former is indicated at and the stator at 2. The is very in probable. primary brushes are shown at 3 and 4, respec The fields of the motors in Figure 3 may be sep tively connected to a source of current supply arately excited, either with or without series field indicated by a trolley line T and to ground G, windings but in the arrangements shown in Figs. and the secondary brushes are shown at 5 and 6 4 and 5 the notors are preferably provided with arranged in quadrature electrical relation to the series field windings as in that shown in Figure 2, primary brushes and 2. The commutators as I claim: 3 30 sociated with the rotor winding are indicated as 1. A rotary transformer having a rotor pro two concentric circles of segments 8 and 9. In vided with a primary brush Set and a secondary Figs. 2, 4, and 5 the load in the secondary circuit brush set located substantially in quadrature elec is indicated as comprising two moto's f0, con trical relation with Said primary brush set, one nected between the primary and Secondary brush only of said primary brush set being asso 3 35 brushes in the well known figure-8 connection, ciated with one of Said commutators and being and in Figs. 1 and 3 the load, which in Fig. 1 connected to a source of electrical supply, said comprises two motors 2 and 3 and in Fig. 3 other primary brush and said secondary brushes comprises a single motor 4, is included between being associated with the other commutator, a the secondary brushes in the Well known CrOSS load circuit, and means for connecting said load 40 connection. In Fig. 1 the rotor of the metadyne trans circuit across said secondary brushes.