w.. w „M A . .m. G.».».„A W.A .„ F.¢„- m AD" ß m „A M V, @y M, DAM w, n Jan. 14, 1947. G. A. ._Ewls Y 2,414,232 TRANSFORMER Filed Jan.- 2, 1945 , ^ 447 / 4 Sheets-Sheet .'5 v2z? ‘im /z Z‘ì’ Hummm 49 FT \345.6. y É- . 5 ' @zo VfR/2 ¿fw/5' i INVENTOR. ' Jan. 14, >1947. G, A, LEWS 2,414,232 TRANSFORMER .Filed Jan. 2, 1945 _FT-5.11. 4 Sheets-Sheet 4 g/„Í‘ y Patente-d Jan. 14, 1947 2,414,232 y UNITED STATES PATENT OFFICE 2,414,232 'rRANsFoRMER Glover A. Lewis, Houston, Tex. Application January 2, 1945, serial No. 571,053 ` 15 claims. (cl. 17a-119) 1 This application is-in part a continuation of my prior copending _application Serial No. 408,008, ñled August 23, 1941.- ' This invention relates to transformers and has for its general object the provision of a trans former in .which the output current and voltage can be morej'accurately controlled than in pre vious types of transformers. In various types of work, and particularly the electrical welding service, it is essential that a transformer for producing the current to be used be capable of very accurate control in so far as its current and voltage characteristics are con 2 provide means whereby said reactance may be adjusted. Other objects and advantages of this invention will become apparent from the following descrip tion taken in connection with the accompanying drawings, wherein is illustrated one embodiment of this invention. In the drawings: . Fig. 1 shows a side elevation of a welding ma chine including a transformer constructed in ac cordance with this invention. _ Fig. 2 is a horizontal transverse section sub stantially on the line 3-3 of Fig. 3. cerned. Various attempts have been made in the ' Fig. 3 is a side elevation of the same machine past to provide transformers having the desired 15 with the guard removed, showing the relative po characteristics, but in every instance certain un sitions of the various parts of the transformer. desirable characteristics have accompanied the Fig. 4 is a view similar to Fig. 2, but with the guard removed. it has not been possible with previous construc Fígfä is a side elevation showing the coil ar- tions to provide for a substantially constant cur 20 rangement of the transformer, the other parts rent output from the secondary coil of the trans thereof being removed for the purpose of simpli former without the characteristics of the output fying the illustration. current with respect to its wave form, etc. chang Fig.` 6 shows an elevation of the same structure ing greatly as the load changes. It has also been as illustrated in Fig. 5 taken at right angles impossible with previous known transformer con thereto. ' structions to alter the open circuit voltage of the 25 Fig. 7 is a top plan view of the structure shown secondary coil. desirable characteristics obtained. For example, in Fi‘g. 5. Fig. 8 shows the electrical diagram and illus provide a transformer in which the voltage of the secondary coil may be controlled to vary as 30 trates the connectionsbetween the various coils shown in Figs. 5 to 7 inclusive. desired as the current in the secondary coil varies. ~ Fig. 9 is a top plan view of the secondary coil It is an object of this invention, therefore, to It is a further and more specific object of this invention to provide a transformer in which the voltage supplied by the secondary coil will drop as the current flowing in the secondary coil in 35 creases in value so that by an increase in the current flowing in the secondary coil, the voltage ` across the secondary coil may be made to vary from a maximum to substantially‘zero. , It is a further object of this invention to pro 40 vide a transformer of the type referred to in which _the open circuit voltage of the secondary coil may be adjusted to whatever value ma.v be desired. forming a part of this invention, parts of the covering for the same having been broken away and shown in cross section for the purpose of illustration. Fig. 10 is a fragmentarywgiew illustrating the manner of arranging the windings of the sec ondary coil shown in Fig. 9. Fig. 11 shows a longitudinal cross section of the composite winding illustrated in Fig. 10. ' Although a transformer constructed in accord ance with this invention may be mounted in any desired manner most convenient for the use to which it is to be put, one desired form is illustrat It is a further object of this invention to pro vide a transformer ofthe type referred to in which 45 ed in Figs. l to 4 inclusive. In these figures it will be seen that the, transformer is built on a the secondary coil will provide a substantially frame presently to be described, and that this ' constant current output over a wide range of frame adjacent one end carries an axle I, on the resistance in the secondary coil circuit. opposite ends of which are mounted wheels 2. Another and more specific object is to provide 50 Adjacent the opposite end the frame is provided a transformer which will supply a substantially constant current to an arc of varying length. with a swivel mounting 3 on which is carried a~ caster wheel ê. Thus, a three-wheel support is Another object of this invention is to provide provided for the device so that it may be readily a transformer in which a predetermined reactance transported to any location desired. will be present in the secondary circuit and to 55 For further ease in transporting the machine, asi-gasa . ê I able current. The primary coil is supported by .it is provided with a pair of upwardly and rear wardly inclined bars 5 adjacent one end, these bars being joined at their upper and -rear-most means of a pair of insulating beams 3G, which are in turn carried on the brackets 3i and these brackets are welded or otherwise suitably secured ends by means of a cross bar t. The bars 5 are secured by a suitable means, such as welding or Cl to the straps 2 I , as shown at 32. The secondary coil 33 ofthe transformer like the like, to the frame of the transformer at their lower ends ‘l and at some intermediate point. wise surrounds the center leg 2l of the core and is such as the point 3. carried on insulating beams 3G, which are in turn ' supported by bars 35 extending through the in The transformer may be handled and trans ported from one place to another by means of a 10 terior of the secondary coil. These bars are se cured at their upper ends to the lower ends oiîav crane or a hoist and for this purpose there is pro pair of cables 36, which are in turn carried by the vided a Abail 9 adapted to be engaged by a hook or sheaves 31 on the gear box 25. The sheaves 3l other connecting member carried by such hoist. are adapted to be rotated to raise or lower the For the purpose of protecting workmen against secondary coil 33 by means of a crank 38 that accidental contact with parts of the transformer, serves to actuate the gears within the gear box` which might be charged with high vo1tage,~and 25 for this purpose. By the means just described, for the purpose of protecting the transformer ' the secondary coil may be located at any level desired between its lowermost position, inwhich it rests upon the angle supports I5, and its upper position, in which it would contact the beams 30. The terminals 39 and til of the secondary coil are connected through flexible conductors di and ¿l2 with suitable binding posts 53 and @it on the terminal board 45, which is provided for this pur against accidental damage caused by heavy» or sharp objects being brought into contact there with, the entire body of the transformer is pref erably enclosed by panels 9 of sheet metal, or any other desirable material, and part of this enclo sure preferably is in the form of a wire mesh I0, so as to provide ample circulation of air for the pur pose of cooling the transformer. Also, a door II may be provided for the purpose of permitting access to the terminal board of the secondary coil, as will be presently described. On the outside pose. ‘ The terminal board 55 is mountedin a sta tionary positionv by means of suitable brackets 46, welded or otherwise suitably secured to the straps of the housing, and preferably adjacent the han-` die bars 5, will be located the main switch I2, con trolling the supply to the primary of the trans former. - Referring now more particularly to Figs. 3 and ' 4, it will be seen that> the frame members I3 and ‘ i4, which are directly supportedby the wheels 2 and ê, serve in turn as supports for the angle irons I5, which extend from one of these frame . members I3 to the other member I3. There are two such vangle irons I5 which are clamped to the opposite sides of the core I6 of the transformer by means of bolts I'I, or the like. The core I6 is shown as comprising a rectangu lar frame, having end portions, side portions 20, and a center leg 2l, thus forming two windows I8 and I9 therethrough. The frame and windows are vertically disposed. 'I'he aggregate cross-sec tional area of the side portions 2l! of the core is the same as the cross-‘sectional area of the center leg 21, as best shown „in Fig. 2. 'I'he same is true of the aggregate cross-sectional*` area of the end portions. Thus the side and end portions of the core have a joint flux-carrying capacity equalto that of the center leg. Hence the core pro vides a closed magnetic circuit of substantially i uniform íiux-carrying capacity throughout, or, in. other words, the flux density, under no load conditions, is the same in all parts of the core. The side upright portions 20 of the core are pro ‘vided on their opposite faces with metallic straps 2l secured thereto by bolts 22 for the purpose of holding the core together, these straps being welded at 23 to the upper edges of the angle irons I5. At their upper ends these straps are bolted to the downwardly extended flanges of the angle irons 24., the upper flanges of which extend toward each other across the top of the core. The angle irons 24 extend along the entire length of the upper cross member of the core and serve as a support for the gear box 25, the same being se cured thereto by cap-screws 26. 30 20, or to any other suitable stationary portion of the frame of the transformer. 'I'he secondary coil 33 is of a special construc tion illustrated in Figs. 9 to 1l inclusive, as will be presently described. Disposed inside the windows I8 and I9 and ex tending through these windows, but in a substan tially vertical position, are auxiliary coils 47 and 38. These coils are adapted to control the leak age flux between the primary and secondary coils of the transformer when under load, as hereini after explained, so as to control the output volt age of the transformer under load. -“Leakage flux” as here used, is that ñux which links the pri-> mary or the secondary coil but not both, and which is due toand exists only during the loading of the secondary. These auxiliary coils are pref erably wound ñat in the form ordinarily called ' "pan-cake” coils and are not provided with a magnetic core. Instead they are merely coils withv an air core. These two auxiliary coils have their similar ends connected by means of the con ductor Q9, which may be integral with the con ductors forming the two coils. The other like ends of these coils are connected by conductors 50 and 5I respectively with suitable binding posts. 43 and 52 on the terminal board 45. It will be noted thatthe binding pbst 43 serves as the ter minal both for one end of the'secondary coil 33 and for one end of the auxiliary coil 48. The load may then be taken from the binding posts 4B and 52, which will place the secondary coil 33 in series with the two auxiliary coils. 1f it be desired to use the transformer without the two auxiliary coils, the load may be taken from the binding posts 33 and ¿34. Access to the terminal board 45 may be had as heretofore stated through the door Il in the housing. It should be noted also that the frame outside the housing is provided with a pair of upstanding posts 53 of any suitable formupon which the leads for connecting the second ary coil to the work may be wound when not in -Surrounding the center leg 2l of the core and ' 70 use. extending through the windows I8 and I9 there of, adjacent their upper ends, is the primary coil 28. This primary coil may be of any. desired form and the leads 29 therefrom extend to the switch The secondary coil is preferably formed as in dicated in Figs. 9, 10 and 11 of the drawings. In these figures it will be seen that the coil is made up of a plurality of turns, such as designated by I2, through'which this coil is supplied with suit 75 the numeral 5d. These turns are individually aangaan y ~ _ insulatedfromeachotherbyßnysuitable insulat , 6 duce a stabilizing effect on the -current supplicav _ ing covering. such as the tape il, 'or any enamel to an arc employed'in welding. By .making it or any other form of insulation that may be found possible to lreduce the open circuit voltage of desirable. The -turns - themselves are each made the -secondary coil, and by providing. a leakage up of ltwo parallel ribbons 56 of copper or other path between the turnsof the secondary coil both good electrical conducting material which is pref when it is loaded and when it is open, they assist erably non-magnetic. Interposed between’ the . in preventing a great surge of current whe'n strik copper ribbons along those portions ot the coil ing an arc, and as-the arc is maintained in the extending> through the windows of the trans course of welding it has been found through much former core there are interposed a pair of soft 10 actual experience that the presence-of thesesoft iron sheets 51. 'I‘hese -soft iron sheets are of iron sheets or laminationsftends to stabilize the slightly less width than the copper ribbons but -i-alnount of current ñowi'ng from the secondary extend a substantial distance axially of the coil ' j and prevents fluctuations in ~that -current which and parallel -with the leg 21 of the core. These would impair the quality of' the weld produced. _ iron sheets preferably extend only along those - The reasons for this are -not fully known, but it portions of the coil which areto be disposed within or closely adjacent tothe core windows. It has been found that if these soft iron lamina is known that the presence of thes'e .windings greatly improves the characteristics of the cur rent iiowing from the secondary coil of a trans-- tions are permitted to extend substantially out former, such as described, when the same is em- - side of the core windows they will cause obiec» 20 ployed for arc welding purposes. tionable heating of the coil. However, such ex It‘has further been discovered that the pres tension of the magnetic laminations 51 would not ence of the soft iron laminations in the secondary prevent the operation of the device in the manner causes the secondary to produce,_when loaded, a hereinafter described. Y y _ current of slightly different frequency from the » In operation the parts will be assembled as in 25 supply. The reason for this is not known. dicated in Figs. 1 to 4 inclusive. A source of al It has been stated that the take-oil leads may ternating- current, electrical energy of the proper be attached so as to take off directly from the frequency and voltage, for which the machine ends of the secondary coil, or toi/take oil from the may be designed, is connected to the primary coil secondary coil in series with the two auxiliary through the controlling~ switch i2. The leads 30 coils t1 and 4i). If. it be desired to exercise no which are adapted to conduct electricity from the control upon the leakage between the primary secondary coil to the point where it is to be used and secondary coils during the time.the trans may be secured either to the binding posts 44 former is loaded, other than the control made and 52, or to the binding posts I3 and 44, accord possible by the laminations 51, then the take-off ' ing to the operation desired. . ' will be directly from the terminals of the sec At this point the open circuit voltage of the ondary coil and the take-oli and leads will be secondary may be adjusted by raising or lower _ connected to the binding posts 43 and 44, ing the secondary coil through _the use of the If on the other hand, it be desired that-the crank 38, the fgears within the gear box 2i, the -leakage be controlled by the amount of current sheaves 31 and‘the wheels 36, which suspend the 40 being drawn from the secondary coil, the take secondaryl coil, It is noteworthy that ordinarily oii will be from the binding posts 44 and 52, so the moving of, the secondary coil, located as this that the auxiliary coils 41 and 48 will be in series ` secondary coil is located, toward or away from the with the secondary coil. It will be seen that when primary coil'would not change its open circuit this arrangement is employed, no _current will voltage. However, in the present invention, the . flow in the auxiliary coils when there is no load open circuit voltage will-change as this coil is on the secondary. Since the side‘iegs 20 of thé moved because of the fact that greater leakage is core have a total capacity for carrying magnetic provided by the` presence of .the soft iron lamina flux which is equal to that of the center leg, there tions 51 interposedin the windings of the sec will be no leakage flux through the auxiliary coils ondary. The presence of the laminations pro 50 »when there is no current flowing in them or in vides a path for a portion of the magnetic ilux the secondary . except perhaps a very slight to pass between the successive convolutions of amount of flux due to self induction. Therefore, the secondary coil to the bottom cross member the auxiliary coils will not substantiallyailect of the core instead ofv passing through the cen the no load voltage supplied by the transformer. tral window of the coil following along the leg 21 55 However, when the transformer secondary- is of the core as would otherwise be the case. 'I’he loaded at all, any current flowing in the sec-Y amount of -leakage through these soft iron lami ondary coil will also ilow through the two aux nations in the secondary winding changes as the secondary coil is` moved toward and away fromA the bottom cross member of the core, because 60 as the coil is moved toward and awayfrom the bottom cross member of the core, these soft in iliary coils and this current will tend to promote leakage ñux through the space between the pri mary and secondary coils, such flux also linking either the primary or. the secondary- depending.l on the direction in which the auxiliary coils are serts or lamìnations are brought closer to or sep -wound and connected to the secondary. In other arated further fromthe iron of the main body words, if these auxiliary coils 41 and 48 are conof the core. The result is that when this leak 65 -nected with one terminal to the secondary, they age is great, as when the coil is near the bottom would, for example, promote leakage in one di cross member of the core. there will be less volt rection as the flow of current increases and would age -generated in the secondary coil than there - hence lower the closed circuit voltage of the sec will be when the coil is moved farther from this ondary coil and limit the amount of current that bottom cross member and the leakage thus de 70 can now from the secondary coil. 0n the other creased. - ' When a transformer of the'type to which this description relates is employed in connection with ' arc welding, the soft iron lamination; 51 play an additional advantageous role‘in that they pro hand, if connected in theopposite direction, the auxiliary coils would tend to promote leakage in the opposite directionmore and more as the cur rent ñowing in the secondary coil increases, and 75 by virtue of this effect would tend to cause the aaraase ' f '7 . closed circuit voltage of the secondary coil not to drop, but in some instances actually to increase. . dow, a means for moving said secondary coil to From the foregoing it will be` seen that a means ondary coil comprising a wound electrical con ward and away from said primary coil, said sec has been provided in a transformer whereby the ductor of non-magnetic material, and bodies o! open circuit voltage of the transformer may be 5 magnetic material extending along said conduc regulated, whereby the working characteristics tor in electrical contact therewith and interposed - of the current produced by the secondary of the `between the windings thereof along those por transformer may be governed so as’to be more - tions ofA said coil which extend through said win-v suitable for welding purposes, and whereby mag dow, and said bodies of magnetic Vmaterial being netic iiux leakage can be regulated according to 10 discontinuous along the portions of said coil which the load placed on the transformer without in l do not extend through said window. Í any way affecting the open circuit characteristics 6. A transformer comprisingva core having a thereof. Means has thus been provided for carrying out . window therein, a primary coil having a part all the objects and advantages sought by this in vention. Having described my invention, I claim: lhaving a part extending through said window and an auxiliary coil having a core composed en tirely of non-magnetic material, said ñrst men _extending through said window,_a secondary coil 1. An electrical transformer having a. core with a, window therein, a secondary coil comprising a wound electrical conductor having a portion thereof passing through said window and.means tioned core being so proportioned that the flux i . density is substantially uniform throughout with substantially no tendency toward the production of leakage flux by-passing said secondary coil providing a'path for magnetic ñux between the windings of said conductor, said last mentioned during periods of no load on the secondary coil, said auxiliary coil being disposed within the path means comprising a body of magnetic material in of and transversely of the direction ofl any mag terposed between each of a plurality of adjacent 25 netic leakage ñux between said primary'and sec portions of said conductor of said Secondary coil ondary coils, and said auxiliary coil being con and being continuous along those- portions of the nected in series with said secondary coil where secondary coil which pass through the window of by a load on said secondary coil will induce av the transformer core, said body being in electri leakage ñux between said primary and secondary cal contact substantially throughout its extent 30 coils. with an adjacent winding ofv said secondary coil. '7. A transformer having a core providing a 2. An electrical transformer having a core with closed magnetic circuit of substantially uniform a window therein, a secondary coil comprising a cross-sectional area throughout, spaced primary wound electrical conductor having a portion and secondary coils surrounding said core, _and p thereof passing through said window and means 35 an auxiliary coil with an air core surrounding a providing a path for magnetic ilux between the portion ofthe path which any leakage-flux be windings of said conductor, said last mentioned tween said primary and secondary >coils would „means comprising a body of magnetic material tend to take. said auxiliary coil being connected associated with each of a plurality of the in in series with said secondary coil. ’ dividual turns of said secondary coil and being 40 8. A transformerl having >a core providing a continuous along those portions of said second closed magnetic circuit of substantially uniform ary coil which pass through the window of the cross-sectional area throughout, spaced primary transformer core. and .secondary coils surrounding said core, and-> - 3. An electrical transformer having a second ary coil comprising a wound electrical conductor an auxiliary coil with an air core surrounding a ¿ portion of the path which any leakage iiux be-- and means providing a path for magnetic ñux _, between the windings of said conductor, said last> mentioned means comprising a body of magnetic tween-said primary and secondary coils would tend to take, and means for passing a current' through said auxiliary coil toinduce and vary the amount of magnetic leakage therethrough. material incorporated in> each of a plurality of adjacent turns of said secondary coil along those 50 9. A transformer having a core providing a ' portions'of said secondary coil, which‘are dis closed magnetic circuit of substantially uniform posed. within a window of the transformer core, - and said body of magnetic material being dis continuous along those portions which do not pass through such window. d. An electrical transformer having a second cross-sectional area throughout, spaced primary i and secondary coils surrounding said core, andan auxiliary coil with an air core surrounding a por 55 tion of the path which any leakage flux' between ' l ' said primary and secondary coils wouldtend to ary coil comprising a wound electrical conductor take, said auxiliary coil being connected in series and means interposed between the windings of with said secondary coil, the connection between j saidv electrical conductor providinga path for said auxiliary and secondary coils being such as magnetic flux between said windings, said last @o to cause an increase in the leakage through said mentioned means comprising a plurality of spaced vbodies of magnetic material interposed between adjacent windings of saidsecondary coil, said ' bodies being disposed along those portions of said auxiliary coil _when the load on said secondary K coil is increased.' 10. A transformer having a, core including‘an l I‘SèÓt'-, v ' elongated portion and a cross member 'in secondary coill which are adapted to be disposed 65 ing said elongated portion, spaced within a window of a transformer core, and those ‘and ,v portions of the secondary coil which do not pass ` tion, secondary saidsecondary coils surrounding coil being'movable,toward@`~ said- elongated through such window of the. transformer core having no such magnetic bodies interposed there andv away from said cross member _of the core@ and means included in said secondarycoil com--„j„` in. ' ‘ 5. In a transformer, a core having a window therein, and primary coil surrounding saidcore mprising betweenathe body windings of magnetic of the material secondaryinterposed "colland' j forming an increasing leakage path as said sec-1 and having a portion extending through said .ondary coil is moved toward the cross member. " window, a secondary coil surrounding said core ll. A transformer having a core including and having a portion extending through said win 75 elongated portion'- and a cross member 2,414,232 i ~ ‘ing the same, spaced primary and secondary coils 1o e - surrounding said core, said secondary coil being mary and'secondary coils would tend to take, said auxiliary coil being connected in series with said movable toward and away from said cross mem « ber of the core, means included in said secondary a leakage iiux linking said secondary coil-when secondary coil in such a manner as to promote coil‘and forming an increasing leakage path as current ñows through thesecondary and auxiliary> saidlsecondary coil is moved toward the cross member, anauxiliary coil with an air core sur coils. ` - rounding a portion of the- path of- leakage flux between said primary and secondary coils, said auxiliary coil being connected in series with said secondary coil, the connection being in such di rection as to increase‘the leakage through said - 14. An electrical transformer having a core with a window therein, a secondary coil having a portion thereof passing through said window, » said coil _being formed of a wound composite con- A ductor comprising a pair of conducting strips, and ' a body of magnetic material interposed between auxiliary coil when a load is placed on said sec-said conducting strips along those portions of the v '- `ondary coil. coil which pass through the window oi the trans 12. A transformer having a core providing av 15 former core, said body providing a path for mag closed magnetic circuit of substantially uniform . netic flux. cross-sectional area throughout. spaced primary 15. An electrical transformer having a core constituting a closed magnetic circuit and com and secondary coils surrounding said core, an auxiliary coil with a- non-magnetic core sur rounding a portion of the path which any leakage flux between said primary and secondary coils would tend to take, and means for passing a cur-' vrent through said auxiliary coil. > prising a frame having cross-members connected by a central> leg, primary and secondary coils surrounding said central leg, said secondary coil comprising a conducting ribbon, and sheets -of v . magnetic material interposed between turns of 13. A power distribution transformer having a core providing a -closed magnetic circuit of sub said ribbon, said sheets extending a substantial distance axially of said coil parallel with said leg stantially uniform cross-sectional area through out, spaced primary and secondary coils sur rounding said core, and an' auxiliary coil with a - and providing leakage paths through said coil over >which magnetic ñux may pass to or from one oi ' - non-magnetic -core surrounding a portion of the path which any leakage’fiux between said pri said cross-members. y . GLDVER A. LEWIS.