March 2, 1937. J. M. PESTARIN 2,072,768 ELECTRICAL GENERATOR SUPPLYING Two LOADS, ONE Af WARIABLE WOLTAGE AND ANOTHER AT CONSTANT VOLTAGE Filed Aug. i5, l934 6 Patented Mar. 2, 1937 2,072,768 UNITED STATES PATENT OFFICE 2,072,768 ELECTRICAL GENERATOR SUPPLYING TWO OAOS, ONE AT WARIABLE VOLTAGE AND ANOTHER AT CONSTANT VOLTAGE Joseph Maximus Pestarini, Grant City, Staten sland, N. Y. Application August 15, 1934, Serial No. 40,011 29 Cairns. (C. 2-239) This invention relates to electrical plants where The invention here considered is a special in two loads have to be supplied with direct current, provement of the metadyne generator object of one load, let us call it the main load, requiring a continuously varying voltage, and another load, my U. S. Patent No. 2,038,380 and it will be easier 5 let us call it supplementary load, requiring a con understood if the latter application is borne in Stant voltage. mind. A Diesel electric locomotive is an important In a metadyne the primary current is auto example of such a plant. The traction motors matically so adjusted as to create by its ampere constitute the main load requiring a voltage vary -turns combined with the stator ampere turns pro 0. ing continuously with the speed of the train, and duced along the primary axis, a flux, called the primary flux, inducing an electromotive force 10 the auxiliary machines, such as the air condition between the secondary brushes and no electro ing machines, the heating resistors, the ventila motive force between the primary brushes, of such tors, the compressors, the battery, requiring a value as may be required for inducing between constant voltage. In the present state of the art the secondary brushes a secondary voltage as re two electrical generators are provided; a main quired by the main consumers for maintaining a 5 generator which with a suitable field adjustment constant secondary current. As explained in the supplies the traction motor load and an auxiliary above patents, when the operating conditions generator which supplies current at constant volt vary, the secondary voltage varies and the pri age to the auxiliary machines. mary current which produces the secondary volt 20 An object of my invention is to provide an elec age inherently adjusts its value correspondingly. trical system wherein a metadyne dynamo-elec If the primary brushes are connected to an aux 20 tric machine is utilized to provide simultaneously iliary source, called primary source of the elec a variable potential source of electrical power and tric power supply, supplying current at a sub a constant potential source of electrical power. stantially constant voltage, the primary current 25 According to the present invention only a single will traverse this auxiliary source. Let us indi electrical generator will accomplish both duties cate this current by I'. 25 in a simple and economical way and with less If a supplementary load is then connected to the weight. The single generator is a metadyne pro primary brushes of a metadyne constructed as vided with special windings, described herein explained above without any auxiliary stator 30 after. winding, the current, is, required by the supple A metadyne is an electrical machine described mentary load, has to be supplied completely by 30 in many previous United States patents, for in the auxiliary primary source, as the metadyne stance in Patents No. 1,969,699, No. 1,945,447, No. generator cannot afford to modify its primary 1962,030 and essentially consisting of a rotor current, the primary flux being completely defined 35 with winding and commutator like a conventional by the secondary voltage. dynamo and of a stator affording a magnetic cir It is desirable that the supplementary current 35 cuit of low reluctance to the fluxes created by Is required by the Supplementary load be supplied the rotor ampere turns; two sets of brushes are generally provided, the current traversing one set by the metadyne and not by the primary source, 40 that is, that the current supplied by the primary inducing by its rotor ampere turns an electro source remain substantially unchanged when a 40 motive force between the brushes of the other supplementary load is connected to the generator, set, one set, called primary and traversed by a and this result may be obtained by providing the current called primary, has its brushes kept at a metadyne with a special stator winding, let us constant voltage difference, the other set, called call it S. Such a winding may be constructed and secondary and traversed by a current called sec arranged so that when a current flows there 45 ondary, has its brushes connected to the con through it produces a magnetomotive force which sumers or electrical load supplied with current by the metadyne. substantially compensates for the primary rotor A description in detail of the metadyne prin ampere-turns which would be created by the cur ciples is given in a paper entitled "Esquisse sur la rent that traverses this special winding S, if this Metadyne' by J. M. Pestarini, in the "Bulletin current traverses the primary rotor winding. This 50 Scientifique A.I.M.' No. 4, April 1931 of "L'Asso winding S is connected in such a way as to make ciation des Ingeneurs Electriciens' published by the current Is supplied to the Supplementary load the 'Institut electrotechnique Montefiore' Liege, traverse the special winding S, and the primary Belgium. auxiliary source is connected so that the current I' is supplied by this auxiliary source of electrica 55 2 2,072,768 power supply to a point intermediate the connec primary source; Fig. 5 illustrates a further in tion of the Winding S to the primary circuit of provement allowing for a satisfactory means of the metadyne armature. charging the battery, and Fig. 6 illustrates the The operation will be more clearly understood application of the present invention in combina by a consideration of the currents, voltages, and tion with my copending application Serial No. 5 5 magnetomotive forces under different operating 735,003, filed July 13, 1934, describing an arrange conditions. If no supplementary load is on the ment suitable for Diesel-electric locomotives. generator, the metadyne rotor primary current Relating to Fig. 1, the metadyne is driven equals the current supplied by the primary auxili by a prime mover 27, such as a Diesel engine, ary source of electrical power Supply and, since and is shown having its primary brushes a and C 10 10 in the usual metadyne dynamo-electric machine connected to the terminals 0 and fit of a pri the voltage induced between the primary brushes mary source of direct current at an essentially a and c is less than the voltage impressed thereon Constant voltage, and having its Secondary by the primary auxiliary source of electrical power brushes b and d Supplying with current at vari 5 supply, a current I will flow in a given direction able voltage the main electrical load, such as from the auxiliary source of electrical power Sup motors 2 and 3, which constitute the main load. ply through the primary rotor circuit. At the in The supplementary load is indicated by a resistor stant that the supplementary load is connected, 4 and a motor 5. The current Is Supplied to the a current Is will be supplied thereto, and this cur auxiliaries constituting a supplementary load traverses the stator winding 6 which substan 20 rent Is will flow through the stator Winding S. Let tially compensates for the primary rotor ampere us assume that, since the induced voltage between turns created by the Supplementary current Is the primary brushes a and c due to the rotor when this current flows through the primary secondary current armature reaction is less than rotor circuit and has therefore no interference the voltage of the auxiliary Source of electrical with the ampere turns due to the magnetizing power supply, this current is supplied from the current I, as explained above, drawn from the auxiliary source of electrical power supply, and primary source, the terminals of which, O and that the current I' will continue to flow in the , are shown directly connected to the primary same direction in the metadyne armature primary brushes a and C. The Supplementary load may circuit. This current IS eXcites the field exciting 30 30 winding S, and provides primary ampere-turns be switched on or off, it will not affect the result which are cumulative with respect to the rotor ant ampere-turns in the metadyne and therefore primary ampere-turns and cause a higher voltage it will not affect the value of the primary and to be induced between the Secondary brushes, re of the secondary voltage. The value of the sec ondary current is determined by the ampere Sulting in a higher secondary current flow. This 35 latter current, in turn, induces a higher voltage turns of the 'secondary variator winding' 2 between the rotor primary brushes a. and c Oppo having its magnetic axis in the direction of the site to the impressed voltage, and, therefore, de commutation axis of the secondary brushes b and creases the current I' supplied to the metadyne d and the value of the primary magnetizing cur rent I' is reduced to the desired amount by means armature primary from the auxiliary Source of 40 40 electrical power supply, and this decrease in the of the "primary variator winding' 7, the mag current I' exactly equals the current is. Thus netic axis of which is in the direction of the con the current I' flowing through the metadyne mutating axis of the primary brushes, a and c, armature primary circuit may be reduced to Zero and which is connected to the primary and Sec or even reversed in direction from the original ondary brushes by means of the adjusting resist no Supplementary load condition, but the current ances 8, 9, 3, 4, according to the invention de supplied by the auxiliary source of electrical power scribed in my U.