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Nov. 5,1946. “ ‘ c. P-. Bo'ucHER , TRANSFORMER APPARATUS 2,410,624 ‘ Original Filed April 10, 1940 T2 _ _ _ _ q _ _ _ _ - _ _ _ _ .._ 101 I... l I l I I l I I l 2,410,624 Patented Nov. 5, 1946 umreo srA-ras PATENT ornca 2,410,624 ' ' " TRANSFORMER ArrAaA'rus Charles Philippe‘Boucher, Paterson, N. J., as ‘ slgnor, by mesne assignments, to National!!! ventions Corporation, a corporation of New Jersey Original application April 10, 1940, Serial No. 328,970. Divided and this application February '7, 1941, Serial No. 377,922 .- (Cl. 171-119), 1‘Claim. 1 My application for patent is a division of my co-pending application Serial No. 328,970, filed April 10, 1940. and entitled Transformer appa ratus, now U. S. Letters Patent 2.312.867 of March 2, 1943, and the invention relates to electrical transformer apparatus, and more particularly to electrical transformer apparatus for supplying two or more negative loads, as, for example, in the operation of a luminescent tube system. ' 2 In the accompanying drawing: The ?gure is a diagrammatic representation of a transformer according to my invention. As conducive to a clearer understanding of cer- . tain features of my invention, it may be noted at ‘this point that in the operation of a luminescent sign or display employing one or more luminese centegas ?lled tubes of desired size and configura tion, high potential electrical energy is required. One of the objects of my invention is ‘to provide 10 Ordinarily the desired high potential electrical energy is supplied by alternating-current trans simple, practical and thoroughly reliable trans; former apparatus connected to a standard single former apparatus for supplying a plurality of phase ‘sixty cycle source at either one hundred separate negative loads and for ensuring auto and ten volts or two hundred and twenty volts. matically that substantialiy no voltage difference exists between the secondary circuits throughout 15' In order to supply the highest possible potential across the terminals of a tube without exceeding the entire cycle of operation, and also that the the maximum potential to ground permitted by currents in the ‘various circuits are substantially the fire underwriters, it has been the practice to the same. energize each tube from two coils having their Another object is to provide compact, inexpen sive and highly ef?cient transformer apparatus 20 one ends grounded placing the coils in series and their other ends connected to the tubc By this for supplying a plurality of negative loads and for energizing in a dependable manner the re mainder of said'loads after one or more of them has struck. ' arrangement, each coil section may have induced in it a potential of about seven thousand five , hundred volts to ground, which is approximately Another object of my invention is to provide a 25 the maximum value permitted by the under transformer system in which negative loads of either equal or unequal resistances may be op erated from the same transformer. writers, and yet the voltage across the tube ter minals will be about fifteen thousand volts. In the operation of a single sign or luminous display, it is frequently necessary to use‘a plu ‘A further object of my invention is the provi of luminescent tubes. In order that the‘ sion of a transformer apparatus of the character 30 rality energizing potential may not reach values in described which lends itself to rapid, efficient and excess of those specified by the underwriters, and economical production employing a minimum of since luminescent tubes have negative load char different parts and requiring a minimum of skill acteristics and vary among themselves as to strik in construction, installation and repair. ing and operating potentials, each tube must have Another object is the provision of transformer as its own separate secondary winding. To use a 7' apparatus of the character indicated whichyis separate transformer for each tube would result peculiarly adapted to withstand the varying-con in an exceedingly high cost of equipment. Fur ditions encountered in actual use, including short thermore, the cost of the labor for installing circuiting and grounding, of the whole or parts of the apparatus, without damage to the appa 40 equipment using a transformer for each tube would be obiectionably high because a separate ratus and the consequent necessity for shut-down and replacement or repairs. Another object is the provision of high voltage charge is made for each connection to the source of supply. ' In transformers I have heretofore designed for transformer apparatus of the character indicated operating a luminescent sign or display, these 45 which supplies a plurality of separate loads in objections are removed by placing two or more such a way as to require a minimum amountof secondary windings in series upon a transformer insulation. ' ' core. Each winding comprises two coils and en Other objects will be obvious inpart and in ergizes one negative load. Each coil has associ part pointed out hereinafter. f The invention accordingly consists in the com 50 ated with it a magnetic by-pass of high reluc tance which limits the flow of current through bination of elements, features‘ of construction, the coil to a safe value. The major portion of , and arrangement of parts, and in the several op the main magnetic flux passes through the by erational steps, all as described herein, the scope pass when the current ?owing through the coil of the application of which is indicated in the 55 reaches such a value that it generates a counter appended claim. ‘ 2,410,624 3 4 magnetomotive force which is su?lcient to buck 0| and 92 interposed between the ends of the most of the main mix. As' a consequence of the coils being mounted in series on the core, when the counter-magnetomotive force of one coil causes the main flux to be by-passed through a longitudinal bars. The bar 93 has a central ex tension 830. which abuts the bar 04. Bar 93 also has integral shunt arms 93b and 930 whichex tend closely toward but do not abut bar Bl, form ing therewith air-gaps GI and G2. The member coils is no greater than it was before the ?rst 9| interposed between the end part 93d of bar 93 and longitudinal bar 9| forms a magnetic path coil became loaded. In fact, due to the increased reluctance of its path, the ?ux coursing through of low reluctance, the core parts being held in the core will be somewhat diminished in amount. 10 firm contact by the band I03, preferably of ‘mag Consequently, the remaining coils will not have netic material. Likewise, the member 92 inter as high voltages induced in them 'as if they had posed between the end part 930 of bar SI and the bar 90 forms another magnetic path of low re become loaded ?rst. Moreover, the instant at which the load of the remaining coils becomes luctance, the core parts being held together by operative lags substantially behind the time ‘of the band I04 which also ‘preferably is of mag shunt, the flux then interlinking the remaining striking of the ?rst load. ‘ ' netic material. One of the objects of my present invention The primary coil P is mounted on the central extension 93a of bar 93 and is energized from above and assure a substantially simultaneous the source of alternating current electrical en striking of luminescent tubes although of slight ergy 96 through leads 9‘! and 98. inequalities in voltage‘ ratings. Secondary coil Si is mounted on the end part It may be noted further that in the operation 93d of bar 93 at the point where a space is formed of a luminescent tube sign or display, conditions between part 9311 and bar 94 and between shunt may be encountered which cause a short-circuit arm 53b and member 9|. One terminal of coil ing of part or all of the apparatus. This may be Si is grounded to the core at 99 and its other caused by fog, rain, ice or other moist weather terminal is connected by lead I00 to one terminal conditions in an atmosphere containing dust, of a negative load. Coil S2 is mounted on the mild sulphur-bearing agents in industrial areas, end part 930 of bar 93 at the point where a or salty particles near the seashore. The appa space is formed between part 93c and bar 94 and ratus may also be subjected to a certain amount 30 between shunt arm 93c and member 92. One of shock and vibration. ‘Furthermore, it is not terminal is connected to load by conductor NH. uncommon for insects to pack themselves around The other terminal of coil S2 is grounded to the the tube electrodes and in between them and the core at I02. Coils SI and S2 may be connected supporting metallic structure, thus providing a either in series-aiding or in series~opposition re conductive path around the tube. Under these lationship, the transformer being more particu conditions of operation, the tubes frequently be larly designed for the operation of a load com come short-circuited from terminal to terminal prising a series of tubes, TI and T2, grounded at or from terminal to ground. their approximate mid-point, as at I08. The load must be grounded at its approximate mid Under the conditions of short-circuit, certain heretofore known and/or used transformer ap 40 point, or connected from the mid~point to the paratus, unless specially designed to accommo mid-point of the coils, as by the lead I01, if the coils are connected in series-opposition in order date an excess current, is inclined to excessive heating which results in the ultimate charring that two complete circuits will be formed, one and burning of the insulation and the destruction for each half of the load and its corresponding of the transformer apparatus, necessitating shut 45 secondary coil. Where the coils are connected in series-aiding relationship. the load may be down and replacement or repair. This situation is especially prevalent in certain heretofore grounded at its mid-point to form a complete cir known and/or used transformer apparatus hav-‘ cuit for each half of the load with its secondary ing the secondary winding grounded at its mid coil but this is inclined to cause an unbalanced point. When a luminescent tube energized by 50 operating condition for the transformer and for such transformer apparatus becomes grounded this reason ordinarily is omitted. at one terminal, as indicated above, excessive The coils SI and S2 have induced in them current is inclined to ?ow in one half of the voltages high enough to energize their respective secondary winding while no current ?ows in the portions of the load at substantially the same other half of the winding. The ?ow of excessive 55 instant, where a bucking connection is used and current damages the winding unless it is designed the load mid-point is connected to the common to carry this heavy current. Such a design, of connection of the two coils as by grounding course, requires larger, heavier, and more ex them. There is substantial equality between the pensive coils. Accordingly, another object of my invention is 60 output voltages of the secondary coils. No danger exists of excessive current ?owing through either to provide a transformer apparatus which is in coil because of the peculiarmagnetic shunt con expensive in construction, employing windings of struction provided. Perfectly safe and economi minimum necessary current-carrying capacity cal operation is assured for all conditions of and of minimum cost, and yet. which is of such short-circuiting, grounding, or open-circuiting of construction as to reliably withstand the many . therefore is to overcome the difficulties noted varying conditions encountered in actual. practi cal use. ‘ all or any part of the load of one or both coils. In the event of a short circuit occurring across Referring now more particularly to the prac the whole secondary winding, the coursing of the tice of my invention, attention is invited to the magnetic flux through the core of the transform ?gure of the drawing in which there is shown a 70 er apparatus is substantially the same as it is transformer embodying certain features of my during the conductive periods of its load. The invention. The transformer comprises the longi amount of current ?owing in the winding in this tudinal core bars 93 and 94, upon which are condition of operation is about the same as that mounted primary and secondary windings as encountered under normal operating conditions. noted below, and also the short core members 75 In neither condition of operation does this cur 5 2,410,024 rent rise to such excessive values as to cause ob jectionable heating and damage to the coils. In the event that only one coil section of the secondary winding becomes grounded, the ?ow of an excessively high current in this coil sec tion is effectively prevented by the major por tion of the magnetic flux coursing along a path of intermediate reluctance provided by a, shunt 6 mum of different shaped core members and re— quiring a minimumv of expensive dies, tools and equipment in its construction. It will be seen, further, that luminescent tubes of the maximum length energizable by any existing equipment approved by the ?re underwriters are energized by my transformer without there being present any of the tube puncturing dielectric discharges arm and its associated air-gap. This path ex frequently encountered in the use of’ present tends around and excludes the short-'circuited 10 equipment. Moreover, my transformer meets the section. The portion of the total magnetic flux ‘requirements of ?re underwriters in that the that interlinks the primary winding with the potential from no point to ground substantially short-circuited coil section, that is the minor exceeds 7500 volts. In the operation of my trans portion of the flux, is substantially the same as former there is no'posvsibility of overloading and that interlinking these two under normal oper 15 consequent damage to the secondary winding in ating conditions or under short-circuited oper the event of accidental grounding of either .one ating conditions of the entire secondary winding. or both coil sections of these windings. In all instances, the electromotive forces induced While I have illustrated transformers having in the secondary winding are not so great as to only one or two secondary windings and two or cause the flow of an, excessively high current in 20 four coils, it is to be understood that three or_ the coil sections of this winding. more windings may be employed with associated The transformer of the ?gure has internal core portions and shunts, the additional second shuntpaths which will not be appreciably af ary windings and core members being mounted fected by the casing. The casing, being oppo out from the plane of the construction shown in site only a small portion of the air-gap, will‘have 25 the drawing for example. With the number of little bridging effect. Thus good air-gap control windings illustrated, however, the transformer is possible. Moreover, the transformer is made apparatus is exceptionally compact and yet, be of simpler parts, which can be readily manufac cause of the peculiar core construction and the tured and assembled. ’ relation of this core to the secondary winding, My transformer has the advantages of com it is fully protected from damage under the vari pactness of construction, symmetry of ?ux and ous conditions encountered in use. The com current distribution, and safe operation’under pactness and coil protection feature assures an conditions of short and'open circuits. Further inexpensive, ef?cient and thoroughly reliable more, for a single tube load, or a load compris piece of apparatus. ing two .or more tubes not grounded at their mid 35 As many possible embodiments may be made ' point, where the secondary coils are connected of my invention and as many changes’ may be series-aiding, a high'output potential is obtained made in the embodiments hereinbefore set forth, with nevertheless no more than a safe maximum it will be understood that all matter described potential to ground. Where the load comprises herein, or shown in the accompanying drawing, two or more tubes which are grounded at their 40 is to. be interpreted as illustrative, and not in a mid-point and the secondary coils are connected limiting sense. in series opposition, a condition of balanced volt Iclaim: ‘ ' ages and currents across the two halves of the In electrical transformer apparatus of the load will obtain. There will be dependable oper character described, in combination, two sub ation of each half of the load and a minimum stantially parallel linear core members, one of time lag will exist between the striking of the, 45 said linear members having intermediate its ends two halves. Dielectric discharge between the a central extension joining said other linear two halves of the load is eliminated. Moreover, member and two shunt arms one on either side the transformer is made of a minimum number of said central extension, extending toward but of relatively simple parts which are readily as not abutting said other linear member and form sembled. Finally, the advantage of an internal 50 ing therewith magnetic shunt paths including shunt construction, that is, ‘a minimum oi,’ fring air-gaps of high reluctance; two end core mem ing tdthe casing, is obtained. . bers connecting said linear core members ex Thus it will be seen that there has been pro teriorly of said shunt arms, the connected mem vided in this invention transformer apparatus in bers forming two closed magnetic circuits with 55 which the various objects hereinbefore noted, to said central extension; a primary winding ' gether with many practical advantages thereof, mounted on said central extension; and two sec-'_ are successfully achieved. It will be seen that ondary coils mounted on said linear core mem my transformerv apparatus is exceedingly com ber having a central extension, each secondary pact and rugged in construction and that it lends coil lying between one of said shunt arms-and .itself to inexpensive and efficient commercial one of said end core members. production and installation, employing a mini CHARLES PHILIPPE BOUCHER.