US1288750A

US1288750A - Electrical transformer.

Info

Publication number: US1288750A
Application number: US3904415A
Authority: US
Inventors: Chester H Thordarson
Original assignee: Individual
Current assignee: Individual
Priority date: 1915-07-10
Filing date: 1915-07-10
Publication date: 1918-12-24
Anticipated expiration: 1935-12-24

Description

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ELECTRICAL TRANSFORMER.

l APPLICATIGRPILED JULY 1o. 1915. 1,288,750. I Patented Dec. 24, 1918.

4 SHEETS-SHEET 2.

C. Hl THORDARSON.

ELECTRICAL TRANSFORMER.

APPLICATION FILED JULY l0. 1915.

1 ,288,750. Patented Dea-24, 1918.

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a @ma c. H. IHORDARSON. ELECTRICAL TRANSFORMER.

APPLICATION FILED .IULY I0. I9I5.

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T o all whom t concern:

. UNITED STATES PATENT oELEioE..

CHESTER H. THoEDARsoN, F CHICAGO, ILLINoIs- ELECTRICAL TRANSFORMER.

Be it lknown that I, CHESTER H. THoRDAR- l soN, a citizen of the United States, and a resident ofChicago, in the county of Cook and State of Illinois, have invented certain `newand useful Improvements 'in Electrical Transformers; and I do hereby declare-that the following is a fiill,sclear,*a'n`d'exact" descript-ion thereof, reference' being had to the accompanying drawings, and to the charac- A ters `of reference marked thereon, which forni a part of this specification.

This invention relates to certain new. and

' useful improvements in electrical transformof-transformers. A further object of the invention ist@ prg.

ers and certain of the improvements are more especially adaptable to the core type of trans-A formers while others are capable of adaptationto other. types of transfrrnei's.4

y Among the objects of thel invention are to improve', simplify and increase the. efficiency vide a transformer the partsof which are inade of units which are capable of being readily assembled and, when-.assembledpro-u duce arigid, compact and durable structure.

A further object of the invention is to pro- 'duce a 4novel magnetic circuit structure .for transformers and 'a novel means .0f assembling and maintaining the saine in assembled relation.

A further object of the invention is to produce a novel construction for maintaining .the active and insulating elements of the transfornierproperly cooled.

Another specific object of the invention is vto .provide novel means to maintain the Ac ooling medium incirculation.

A further `object of the invention isto pro- "vide a novel means for connecting the units 0f a winding where said units are inade up of side by side around the core.

' spirally `wound sections which vare disposed .A further object of the invention .is'to pro' vide means for rotecting transformer wind` ings, both the igh and low tension wind- 1 ings, against Vexcessive Aoverloads or surges which'niay be thrown OnthejWindipgs and to thereby prevent burning out of the windinffs.. f

rther objects of the invention will appear from the. following description and the invention consists in the arrangement and Specification of Letters Patent.

' Fig. l0 is a cross section on :Patented Dec. 24, 1918'.

Appiieation flied July 10,1915. serial No. 3am.

combination of elements shown in the draw- I ings, and hereinafter described and claimed.

In the drawings 4. n Figure 1 is a side view o` a. transformer embodying my inventiomfwith the inclosing casing shown in section. Fig. 2 is a vertical longitudinal section thereof. L y

F ig. 3 is an enlarged partial transverse section of the core, the high and low tension windings and the insulating elements asso` ciated therewith. i l

Fig. 4 is'a section on the lined-4 of Fig. 3. Figs. 5 and 6 are details lof the insulating separator` member employed between they Vunits 0f the high tension winding.

F ig. 7 is a diagram illustratingl theelecl 8 is a fragmentary detail illustrating a portion of a surge proof device connected to thehigh tension winding.

. Fig. 9 is a detail illustrating one of the units of the high tension Winding and a mode of stifening the winding.

of Fig. 9.

Fig.A 11 is a detail of the insulatingjoint between the ends of the inner stidening turn the une io-io v'shown in Fig. 9.

' the inclosing casing of the transformer made of a depth to contain a body of oilor other.

'cooling medium which is circulated through and about the active element-s of the transformer. It is provided kwith the usual re movable cover 11, having therein bushings i12 throughawhich the conductors 14; of the -high tension winding circuit extend. The' mode of leading the low tension' winding circuit conductors from the casing is not herein.

shown but they may be led from the casing in any suitable or convenient manner.

The magnetic circuit of the transformer,

' trical connections 0f the low tension winding.

los

which is of laminated construction with the laminas parallel to the path ot the magnetic flux, consists of a core 15, upright end members 1G, 16 and a base member 17. The abut- 5 ting ends of the end and base inembei's of the circuit structure are beveled and meet along oblique lines disposed, as herein shown, iat forty five degrees to the vertical. rThis construction provide-s an increased length of contact between Athe members of the circuit and improves the magnetic joint.4 'n order 2Ol groove formed between simi-lar angle bars 19 attached to the bottom wall of the casing, said circuit members being suitably insulated from the bars and casing walls. This c0nstructionrenders'it unnecessary to clamp the lamin together by means of bolts which pierce the same, or otherwise, and affords means whereby the plates constituting the members are confined in proper relation to each other, and also serves to hold the initeredends of the bottom and end members in fixed relation to each other, the bottom and end guide and confining bars meeting at the lower corners of the casing. The arrangement is such also that the laminae may be slightlyf separated so as to permit oil to pass into the spaces between them to thereby aid in cooling, and avoid the formation of eddying currents in this part of, the circuit-structure.

rlhe core 15 is arranged at an inclination to the horizontal in order to facilitate the flow of cooling oil along said core and the parts mounted thereon, as'will hereinafter more fully appear.

with the said end members 16, and one which lends itself readily to assembling and which produces an ctlicient interlocking connection between the core and "the end members of the circuit, the upper ends of the said end members may be convexly curved to fit downwardly opening concave recesses 20 o the core. The rounded engaging portions ot' the core and ,end members increase the area of contact between the lamine thereofV 'j may be directed.`

and thereby improve the integrity of the magnetic joint at these points. The rounded joining faces are preferable, though not in all cases essential, tor the reason that such a joint admits'o greater ori less inclination ln order' to afford a convenient means for connecting the core the necessity of 'bolts piercing the parts at the joints. Moreover, it permits the core and the windings thereon to bereadily lifted out of place without disturbing the remainder of the circuit structure.

25v designates, as a whole, the low tension winding ot' the transformer and 2G desig-v nates, as a whole, the high tension winding thereof. Each of the said windings, as herein shown, is made of a series ofconnected disk-like or slab units each made of a spirally wound'tiat wire such, for instance, as shown in my co-pending application for U. S.. Letters Patent, Serial No.

744,001, tiled on the 24th day ot January,v

core and winding, the. interlocking conne`c` tion herein shown consisting of undercut or vdove-tail grooves in the bars engaged by like projections at the ends of the spacers. This construction is such that the low tension windings and their radial and longitudinal spacers may be 'assembled acomplete low tension unit of o en work or s 'uirrel cave formation and may be handled as such unit in the assemblage of the transformer.

The low tension winding is shown in Figs. 3 and L.Las mounted on a cylindric insulating sleeve or taping32- which surrounds the core 15 and, as shown in the latter figures, is supi ported on said core by means offlongitudirial insulating slabs 33 which are fiat at their inner sides and engage the flat sides of the core and are rounded attheir outer sides so .that the assembled sets ot' slabs constitute a cylindrie inner support Jfor said sleeve'.' The inner spacer hars 30 rest against said insulating sleeve 32 and form between .the V' low tension winding and sleeve longitudinal spaces 'or channels 36 through which a cooling medium may be circulated.; The radial separators 29 also'provideradial channels 37 (Fig.- 2) between the `winding units outwardly, through' which a cooling medium l order that' the cooling medium may be directed `along 'and incontact with the sides of the core-,the insulating slabs 33' maybe- ,provided at their inner fiat sides with longij tudinally arranged conduits or channels 38,

as shown most clearlyin Fig. 3. The said channels 38 are open at their ends to t-he oil,A

or other cooling medium. space of thev eas-, ing, as best shown in Fig. 1, whereby a free circulation of the cooling medium through will appear that the gravity controlled cir- 65 the said channels 38 from end tolend of the core is afforded. l

The winding units -l-O of the high tension winding surround the low tension winding and are arranged side by side. They are spaced from each other by means of angularly separated, iadiahinsulating spacers 4l to provide between said units radial passages or conduits to direct a cooling medium between the units, The said spacers 41 are,-

interlocked at their ends with longitudinal spacer bars 43 in the same manner `as the spacers 29 and the spacci' bars 30, before described, are 'interlockedl The high tension winding units and said radial and longi'- tudinal spacers may be assembled as a com: plete unit of open work or squirrel cage type and so handled n'asseinbling thepaits l of the transformer.

The high tension winding is separated from the low tension winding by insulating sleeves or

shells

44, 45. The longitudinally arranged spacer bars 43 at the inner ends of the radial spacers 41 ofthe high tension winding rest upon the outer ,insulating shell tension winding longitudinal channels or conduits 46 for a cooling medium. Likewise,

the outermost rspacer bars 30 of the low tension winding engage the inner insulating` shell 45 so as to form between said shell and the low tension winding other cooling medium conduits or channels 49. The two insulating

shells

44, 45 rare likewise separated bya series of longitudinally arranged, angularlyspaced spacer bars 50 (one of which is shown in Fig. '3) which provides'another series of longitudinal `channels or conduits for the circulationof a cooling medium.

Preferably, and as herein" shown, the eX- tended interlockingends of the spacers 4l and 29 do not extend entirely to the bottoms of the undercut grooves ot the spacer bars 43 and 30, respectively, so as to thereby pro vide at .the bottoms of said grooves longitudinal conduits 52 through which a cooling medium may be conducted.

The inclination of the core 15 is Ian advantageous arrangementv in connection with the several longitudinal vchannels or conduits for `cooling medium formed between theactive and insulating'elements of the transformer, as such inclination of the core gives a like inclination to each of the longitudinal .conduits or channels.downwardly through which the cooling'medinin mayvv flow by gravity. Thereby an eiiicient `circulationof the cooling medium is effected. The tendency ot the heated cooling. medium to rise has the effect to carry it upwardly through the several transverse or radial passages or conduits between the units of the high aiidlow tension windings. Thus it radial or trans' aforesaid co-pending application, whereby the edge of each turn of each .winding is. ybai'ed for contact with vthe circulating cool- `ing medium, is of great importance inasnluch as tlie oil iiows freely past` each edge of each turn so that in-terchaiigeof.-.lieat from the wires to the cooling mediuinis greatly enhanced.

The arrangement of the `two insulating

shells

44, 45 between the .high and low tension windings is of considerable importancein coils operating lunder very high tension, inasmuch as the insulating barrier-between the coils is thereby .greatly augmented.. The

arrangement herein shown, whereby the two shells arel separated by spacer vmembers 50 to'forin a coolingmedium conduit between the same, further increases the break-down point between the high and low tension yi windings by reason of the fact that each shell is exposed to the influence of the cool'- ing medium .on both lits inner and' outer Y sides, whereby said shells 'are protected temperature breakdown.

from

The outer shell ,44, or that nearestadje.i=

cent to the high tension winding, is but slightly longer than the said` high tension winding. The-inner shell 45 is considerably longer than the outer shell, but terminates at; its 'ends short of the end members ofgtlie magnetic circuit structure so. as to avoid.

electrostatic leakage along the same to the outer members of said ycircuit structure.

vt one or both ends (both ends as herein shown) of the high tension winding is arranged a surge proof device 55' which is constructed in all essential respects like the surgeproofdevice illustrated in my co` pending application for U. S.V Letters Patent, Serial No.- 793787, filed on' the 6th 4day of October, 1913, with the exception that the y cross sectiongolt the device herein shown is ovalinstead of cylindric as shownVin the aforesaid application. Said vsurge-p'roofjdevice consists essentiallv'of av series ofco'n` ductors of progressively increasing cross sec'- tion, inseries with the high tensionwind ing` and between the turns' of said conductors are adapted to be arranged .one or more resistance elements, as set forthin my aforesaid prior application. As herein shown, the conductors of the surge proof device are Lasarte' so arranged that the conductors of 'pro- V\said parts. The present method is shown in gressively increasing cross section surround the conductors of lesser cross section. The outermost or greatest cross-section conductor is conne'cted to the adjacent winding unit of the high tension Winding by means of a connection 56 (Fig. 4) While the innermost conductor of the surge proof device is adapted to be connected to the external terminal in the manner shown in my aforesaid prior application last above referred to.

As a. further improvement, and to protect the high tension windingfrom the effect of overload or short circuit stresses, the rst two or three winding units of the high tene4 sion winding' adjacent to the surge proof device are made of conductors having lprogressivel)7 decreasing cross' section, the unit at the end of the winding having the largest cross section. As herein shown` three ot' such differential coils 4.0, 40", 409 are employed,.\vith the unit 40 of the winding having coarse or large cross section, while. l the conductors of the units 40h and 4:0C are of progressively decreasing` cross section. The remainder of the units of the w1nding may have conductors of uniform cross section. Furthermore, the insulation between the turns of the

windings

40, 40", Lloc are of progressively decreasing thickness, the insulation between the turn `of the outer most units being thickest. e employment of the three or more outside winding units having conductors of graded cross section and with the insulation between the turns thereof of progressively decreasing vthick-v ness enablesthe high tension winding, as a Whole, to receive greater shocks without injury than if the conductors and the insulation between the turns thereof be of uniform thickness throughout the length of the wind? As a further and separate' improvement in winding units or coils made of spirally wound flat conductors', and in order to me'- chanically brace the units so that they may be individually handled without danger of' collapsing them, and to strengthen them in the assembled transformer, the inner and

outer turns

60, 61 thereof are made of relativelv massive stiff wire.v As herein shown the innermost turns consist of half round cross sections with the attened sides thereof lying against and in metal-to-metal con,-

-tact with the adjacent ends of the flat turns.

In some instances, said windingunits are made principally of-flat aluminum wire and the outer and inner stiil'ehing turns of copper. By reason of the fact that it is not practicable to solder thc thin,`iat wire, constituting the principal part of the winding* unit, to the inner and outer stiteninturns, I have herein rshown a special methc of establishing electrical connection between the Figs? 9, 10 and 1l. It consists, at -the inner and central 'parts' of the units, of laying on the fiat faces of! the inner stiening turns 60 twoor more insulated turns of hat wire 62, somewhat heavier than that of the bodies of the units andinsulated from each other diate thickness flat Wire,- the inner stifening` connecting turns being held assembled by pressure due to the winding 'of Vthe Ware. The inner turns may vbe fastened together at their ends by means oit' insulating dowels 64 which enter at their ends socketsi formed in the ends of the inner turns, and provided between their endsvwith flanges 65 which bear against the flat ends of the inner turns to prevent short circuiting about the inner turns.

As an improved means of connecting the adjacent units 0f the high tension winding the spacer members 41, which extend from the inner to the outer sidesof the high tension Winding, are provided with slits`57 which extend from end to end thereof and are disposed obliquely of the planes of the spacers, and through these slits connecting conductors 58 extend diagonally 'from the outer turn of each Winding vunit to the inner turns of the next adjacent Winding unit. The leads or connections 58 may be soldered to the inner and outer turns of the units. rlhis mode of-connecting the units has the effect of equalizing the'stresses between adjacent windin units :from the inner to the outerturns t ereof.- The extension of the connections 58 through the insulating spacer members insulates said connections trom the turns of the windingsthus connected.

The hi h tension windings are held from endwise isplacement on the outer insulating shell 44:,by means of spacing bars 67 made of insulating material which extends between the end walls of the casing orparts attached thereto and insulating members j 70 arranged `outside of and bearing againsti the surge proof devices 55.

In orderv to avoid corona discharges from the salients of the

members

16 and 17 of the magnetic circuit structure or of the casing, I may provide shields 72 which cover the upper and inner faces of the. members respectively, and are provided wlth outwardly curved rs id ortions which extend to the casing. i Ali e corona shield 73 may be arranged just Within the upper open side of the -casing 10 beneath the cover thereof to avoid corona discharges from the terminals 141 and the top edges of the metallic casing 10.

In Fig. 7 is shown a preferred winding iis Yit

diagram for the-low tension Winding. As shown inj said figure, 7.5 designates the feed lwire and 76 designates lthe return wire of vground so as to thereby enable high tension charges such as are injurious to the Winding, to be tapped off to the ground and danger averted. l

The said lead and return wires 7 5, 76, respectively, are carried outwardly from the low tension winding in groups through the space between the low tension winding and the upper side of the core, as shown in Fig.

3. They are insulated from the low tension 'winding units by insulating shields 7 8, made of mica or like insulating material.

In Fig. 14 is shown a modified arrange ment of insulating the low tension Winding from the core. As therein shown, each corner of'the core is embraced by a longitudinal plate 80, of substantial W-shape in crosssection, said plates being insulated from the core by insulating sheets 81. The said plates are bound together by

tie bolts

82, 83, which may be insulated from the plates by insulating bushings 84 to avoid a closed circuit through said plates around `the core. The edges of the plates support the inner longitudinal spacer bars 30 of the low tension winding, said bars being grooved at their inner sides to receive the edges of said plates.

The last described arrangement avoids the necessity of piercing the plates or laminae of the core to bind them together. The cross section of the plates is such as to give great strength thereto, and also provide ample space -between the core and the/low tenysion winding for the passage of a cooling medium along said parts to maintain the saine properly cooled. l

ln order to prevent the endwise displacement of the shells 4l and l5 with respect to each other and to the core 15 I may provide anchoring means in the nature of lugs or washers 90, shown in Figs. 1 and 2, which are. attached in any suitable manner to braces A(37 and, as herein shown, engage the ends of the shells. inasmuch as said braces are fixed relatively to the frame which carries the magnetic circuit and inasmuch` as the lugs or washers are fixedly attached to the. braces, this arrangement serves to positively hold the shells from endwise displacement with respect tothe fixed parts.`

The Asurge proof device beforelreferred Y to, and designated as a whole by 55 serves,

in addition toy its function v,of .preventing/:j

h'eavy surges coming into the highy tension winding, as corona shields to avoid corona discharges between the ends of the high ten sion winding, along the insulating

shells

44 and 45, to the end members of the magnetic circuit or to the frame which Supports the same. The presence of the conductor ele ment at the ends of the high tension Winding having exterior] y rounded surfaces, such as is presented by the surge prooi device referrer to, has the efect to equalize the elec-A tro-static pressures or stresses alongl thel end faces of the high tension winding and to avoid corona discharges from said ends. So

far as this latter function of thedevice 55 is concerned it may or mgaynot possess the additional characteristics which provide a surge proof device. Further the cross section of the shield, when considered as a corona shield, may be varied from that shown.

lVhen operating in connection with high i voltages it is'desirab'le to provide means for determining the voltage of the high tension o winding` by testing a fractional part of the winding, the turns of which have a known v relation to the total turns of the winding` Y I have shown in Fig. ,4f a practical method of testing the high/tension winding which consists of conigietlng one or more of the units (designated by 91) of the winding with a testingA circuit 92,93 connected to a measuring device, as a volt meter, 9i. ln order that this testing circuit may be safely loro handled I may connect one side thereof to a grounded conductor-05. This method of ,testing thehigh tension V,winding may be applied to'windings speeiiically different from that hereimslibwii, it only beingnecessary to segregate'a definite fractional part of ythe winding, the turns of which bear a definite or known relation to the total turns of the said high tension winding.-

Itwill be understood that the s trlurturalA details of the particularI embodiment of my invention herein shown are capable of con siderable variation within the spirit and scopiof the invention, and that certain ot the improvements are capable of adaptation t0. types of transformers other than that herein shown and specifically described, and further that it is the intent to claim all of inherent noveltyv that is disclosed in `the speciflcation and drawings.

I claim as my invention :4-

1. An electrical transformer -comprising a casing, a laminated magnetic circuit there.- in comprising a base, end pieces and a core,

the latter resting on and removably sup` ported by said ond pieces, said casing be' lng provided with guides to form grooves to receive and confine the base and end members, whereby the latter ai'e held 1n 4place with respect to each other and the laminae of the members are confined solely by engagement with said guides, and transt'oi'iner windings carried by the core.

n electrical transformer comprising a casing, a laminated magnetic circuit comprising a base, end pieces and a. core reniovably supported on the end pieces, the said end pieces abutting against the base 'along butt joints oblique t0 said members, guides in the casing walls between which the laminae oi the base and end members ai'e confined and by which said n'ieinbers` are held in place relatively to each other, and transformer windings carried by the coi'e.

An electrical transformer comprising a casing provided 'at its bottom and ends with conlining guides` a laminated magnetic circuit' comprising a base seated in the bottoni guide and extending at its ends intol the end guides and tapered at its ends, upright. end pieces seated in said end guides and tapei'ed to engage the tapered ends ot said base and a core resting on said end pieces` and transformer windings carried by said core.

4. An electrical transformer comprising a casing provided at its bottom and ends with confining guides, a laminated magnetic cn'- cuit comprising a base seated in the bottom guide and extending at its ends into the end guides and tapered at, its ends. upright end pieces Seated in said end gi ides and tapered at their lower ends to engage the tapered ends of said base and a core removably supported on the lipper ends ot' said end pieces` the end pieces and core being' provided. .one with convexly rounded surfaces and the othe,- with conca vely rounded sui-tace which engage to lorin butt joints of greater length than the width ol' the end pieces. and transformer windings carried by said core.

5. An electrical transformer, comprising a magnetic circuit consist-ing ot' a horizontal` base. upright endv members and a core and. transformer windings carried by the core, one surrounded by the other," and spaced from each other to provide between them a'longitudinal passage, andthe core being inclined to theplane of vthe base to proniote, circulation of a cooling 'luid through said passage.

6. An electrical transformer. comprising a magnetic circuit consisting .of a 'base` end..

each other to )rovide circulating passages.'

and the core being inclined to the plane of the base to promote the circulation ot a cool- .ng fluid through said passages.

7. An 'electrical transformer comprising a magnetic circuit consisting of a. base, end pieces and a core, said end pieces' being conr-exly rounded at their upper ends and the core provided with concave recesses to receive said rounded ends ofthe. end pieces, to

.slightly beyond the ends of the windings.

and the other otf which extends beyond the first shell and tei'ininates short of the end pieces of the magnetic circuit.

Sl. An velectrical transformer comprising a magnetic circuit embracing a side piece, end pieces and :i core. high and low tension. windingsI carried by the core, and two insulating shells between the high. and low tension windings, one of which extends slightly beyond the ends of the windings and the other of which extends beyond the trst shell and terminates short ot' said end pieces ot' the magnetic circuit, there being a circulating passage between the shells for a cooling medium.

l0. An electrical transformer comprising a core, a low tension winding siirroifinding said core. means to provide. between the core and the low tension winding a longitudinal oil passage` an insulating shell surrounding the low tension windii'ig and ay high tension winding surroundiiig said shell and spaced therefrom to torni an oil passage` said core being generally horizontal but slightly inclined so that one end lower than the other to promote circulation of a cooling medium through said passages.

l1. n electrical transformer comprising a core. a low tension winding surrounding the same, means to provide between the coreand the low tension winding a longitudinal oil passage. two shells surrounding the low tension winding` with spacing means between them to provide a longitudinal oil. passage. and a' high tension winding surrounding the outer shell and spaced thereA from to torni an oil passage, said core being inclined, with one end thereof slightly lower than the other.

l2. An electrical. transformer comprising a core, a low tension winding surroundingl the saine, means to provide between the core and the low tension winding a longitudinal oil passage, two shells surrounding the low tension winding, with spacing means between. them to provide a longitudinal oil passage, a high tension Winding surround- -i ingthe outer shell, spacing means between y. the outer shell and thehigh tension winding to form a longitudinal oil passage, said core I beingl inclined relatively to the horizontal, and said'high tension winding being Composed of a-plurality of disk-like,-spirally wound units and radial spacer 'members to provide radial oil passages between said units. Y

13. An electrical transformer comprising a core, high and low tension windings surrounding the core, an insulating shell between the windings, means whereby each winding is spaced from the insulating shell to provide longitudinal cooling passages between the shell and the windings, each of said windings being composed of disk-like winding units with spacing members between the units to provide radial passages for acooling medium.

14. An electrical transformer comprising a core, high and low tension windings there-I on, each winding composed of a plurality of disk-like winding units disposed side by side, an insulating shell between the high and low tension' windings, radial spacers between the units of the windings and insulating longitudinal spacer elements between each winding and the insulating shell to "space the shell from said windings tofprovide oil passages, said vlongitudinal spacer elements being interlocked to the inner and outer ends of the radial spacers.

15. An electrical transformer comprising a core, high and/low tension windings ther on, `each winding composed of a plurality of disk-like winding units disposed side by side, an insulating Shell between the high and low tension windings, radial spacers between the units of the windings and insulating longitudinal spacer bars between each winding and said insulating shell, said bars -being provided with undercut grooves and the radial spacers being provided with lugs to intertit therewith` .saidil ll'ugs terminating short ot' the bottoms ot' the grooves to pro- .vide along said bettomsof the grooves lougitudinal oil Ichannels.

1G. An electrical ti'anstormcr comprising a core, high and low tension windings survroundingthe same, the high tension wind- -ing comprising a plurality ot' disk-like,

winding units, radial spacers separating the units to provide oil passage-s between them. and longitudinal insulatingbars arranged inside. and outside ot' the units and interlocked to the radial spacer members, whereby the units ot the winding are locked together to permit the complete'winding to be handled as a unit.

v1T. In an electrical transformer, a winding composed otl a plurality of spirally wound units, with means tor connecting them to au outer circuit` radial spacers to provide. radial oil passages between the units, and longitudinal bars inside and outside the series ot units interlocked to the ends of the 'adial spacers, whereby the coinplete winding consists of amigd unitary structure.

18. In a transformer, a core, a primary winding thereon, a secondary winding in inductive relation to the primary winding and said core, said secondary winding being composed of a plurality of separately wdund coil sections having substantially flat. faces which oppose'and are spaced from each other, with insulating and spacing strips between them extending transversely across said faces to provide transverse ventilating passage-s between the sections and 'means arranged across the inner and outer edges vof the`coil'sections and engaging the insulating strips to hold said strips. properly spaced and to constitute inner land outer ventilating passages, which communicate with said tra-nsverse passages. `1 9. A, winding for electrical apparatus comprising a plurality of spaced, disk-like\ winding sections, insulating spacers between them and strips extending across the inner andouter edges of said sections and interlocked to the ,inner and outer ends of said spacers. i

20. A plurality of disk-like winding sections, each composed of a flat, bare, rspirally wound wire insulated between the turns thereof, with each edge of each turn bared at the sides ot' the sections, transverse insulating space-rs between 'the sections and inner and outer strips arranged lacross 4the edges ot' the sections and interlocked to the 'inner and outer ends of said spacers.

21. An electrical transformer comprising a core, high and low tension windings surrounding the same, the high tension winding comprising a plurality of disk-like winding units, radial spacers separating the units to `provide oil passages between the units for the circulation of a cooling medium, said radial spacers being provided with longitudinal slots arranged obliquely to their planes and conductors within said slots for connectingthe inner and outer turns o't' adjacent units.

An electrical transformer comprising a casing, a magnetic circuit therein composed ot' a base, end pieces and a core sup-1i ported on said end pieces, high and lou,` tension windings surrounding the core and corona shields inclosing the base and cnil pieces of the circuit and curved outwardly therefrom toward the walls ot' the casing.

:23. An electrical transformer comprising a casing, a magnetic circuit therein embraiing a core, high and low tension windings carried by the core, conductors coiinected to the high tension winding and extendimg` initwardly through au iin'iulating bushing in the casing'wall, and `a corona shield of curvedv cross section surrounding said bushing between the same and the surrounding Ithe ends of the high tension winding, said shields being formed with oppositely facing carved surfaces.

An electrical transformer comprising a. magnetic circuit embracing a core, high and low tension windings, an insulating shell between lsaid windings, said shell terminating shortof the ends of the core and externally curved coron-a shields between the high tension Winding and the ends of the magnetic circuit.

26. An electrical transformer comprising a magnetic circuit embracing a core, high and low tension windings, an insulating shell between said windings, a frame supporting the magnetic circuit and braces endineens@ wise disposed relatively to the axes of the windings, between said' frame andthe high tension winding.

27. .An electrical transformer comprising` a magnetic circuit embracing a core, high and low tension windings, an insulating shell between lthe said windings, said shell terminating short of the magnetic circuit7 a frame supporting the `magnetic circuit, braces between said frame and the high tension Winding, said braces and engaging saidy shell to hold it from shifting endwise.

ln testimony that I claim the foregoing as my invention I affix my signature, in .the presence of two witnesses, this 12th day of June, A. D. 1915.

CHESTER H. THORDARSON.

vWitnesses 7.1). HALL, G. E: Downs;

and means carried by'