AP1302A - Transformer core. - Google Patents

Abstract

A transformer core comprises at least one leg and at least one yoke part, wherein the cross section of the leg or the legs is regularly multi-edged with more than four edges. The core is made up of rings rolled form strips of constant width, whereby any electrical properties are achieved. The transformer is also to manufacture and avoids waste of material.

Description

INVENTTON

Tne present :r.v=n:ion relates aenera.-y to transcormercores arc especially co three-phase arc cne-phase ceresccrr.oristnc recularlv multi-edced lees. 20

BACKGROUND

Three-phase transformer cores are usually made oftransformer plates cut to Ξ I shape for small trans-formers and to rectangular plates, which are laid edgeto· edge, in larger transformers. They have the drawbackthat the magnetic field has to pass via edges fromplate to plate and that the magnetic field must go anunnecessarily long way and not always along a magneticorientation.

Designers of transformer cores have striven to obtainlegs with an essentially circular cross-section becausethat gives the best efficiency of the final trans-former. However, there is always a trade-off betweenefficiency and production requirements, leading to non-optimal transformer cores with non-circular legs.

Strip cores for three-phase transformers have hithertobeen difficult to manufacture. The efficiency of thecore can be increased by cutting strips to variablewidth and winding rings, which are given a circularcross-section for single-phase transformers and semi-circular cross-section for three-phase transformers.This method results in a great deal of waste and thewinding process is time consuming. ΑΡ/ΓΖ 01,02081 25 0 0 1 3 0 2 US 4,557,0.35 '.Mandersori discloses a me choc ci manufac-turing transformer cores using electrical steel stripshaving approximately a linear caper. 3y selecting asue cable caper, a hexagonal or higher order approxtrna- Ξ cron of a circular cross seerion cor the legs of thecores os produced. However, the tapered strips are; dif-ficult ana time-consuming to produce and the design isnot well adapted to large-scale production.

In figs, la-o is shown a prior art three-phase trans--•';10 former core according to Manderson, generally desig- nated 11. The core has a general delta-shape, as isseen in the isometric view of fig. 1, with three legsinterconnected by yoke parts. In fig. la, a cross-sectional view of the cere is shown before final assem- 15 bly. The core comprises tree identical ring-shapedparts 11, 13, and 14, the general shape of whichappears from fig. I. Each ring-shaped part fills up one-half of two legs with hexagonal cross-sections, seefig. la, thus totalling the three legs of a three-phase .,., 20 transformer. The ring-shaped parts are initially wound,from constant width strips to three identical rings12a, 13a, 14a with rhombic cross-sections comprising two angles of 60 degrees and two angles of 120 degrees.These rings 12a-14a constitute the basic rings. The 25 orientation, of the strips also appears from figs, laand lb..

Outside of the basic ring in each ring-shaped partthere is an outer ring lib, 13b, 14b of a regular tri-angular cross-section. The outer rings are wound from 30 strips with constantly decreasing width. AP/T,' 0 1 «2081 ΑΡ Ο Ο 1 3 Ο 2 cores 3

When the three ring-shaped parts 12 - 14 are puttogether, see fig. lb, they form three hexagonal legs on 5 which the transformer windings are wound. A drawback with this solution is that every size oftransformer requires its own cutting of the strips.

Also, the outer rings 12b - 14b are made of strips with 10 decreasing width, leading to waste and it also makes the transformer according to Manderson difficult tomanufacture .

Transformer cores are also described in the following 15 documents: SE 163797, US 2,458,112, US 2,498,747, US __

2,400,184, US 2,544,871, and US 2,333,464. However, the CO above mentioned problems are not overcome by the described in these documents.

20 OBJECT OF THE INVENTION

An object of the present invention is to providecransrormer core wnerem me energy losses areminimised. 25 Another object is to provide a transformer core, is easy to manufacture and avoids material waste

Another object is to provide a method of manufacturing atransformer that is well adapted for large-scale 30 production.

SUMMARY OF THE INVENTION

The invention is based on the realisation that atransformer core with one or more regularly multi-edged 35 legs with more than four edges can be wound of strips of material with constant width.

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r η ya AP/fy o 1, ύ 2 0 8 1 figs. 3a and 3r are oransverse cross-sections of analternative three-phase transformer core with legs withhexagonal cross-section before and after assembly, re-spectively; ΑΡ ο ο 1 3 ο 2 ε;

Fig. 4 is an isometric view of a three-phase trans-former core with octagonal legs;

Fig. 4a is a transverse cross-section of the core shownin fig. 4;

Fig. 5 is 'a cross-section of a transformer leg with tenedges;

Fig. ό is a cross-section of a transformer leg withtwelve edges;

Figs. 7-5 show an arrangement for influencing the leak-age inductance and the harmonics in a three-phasetransformer; rig. is a transvertransformer core with e cross - sect ion cc a tnree-p-nasesceciallv shaced yoke carts for 15 Fig. 11 shows a three-phase transformer core with linedup legs;

Figs. 12-14 show one-chase transformer cores accordingto the invention; and

Figs. 15-17 show further improvements of the shape of20 the transformer core cross-section.

DFTAIhFD DESCRIPTION OF TES INVENTION

Preferred embodiments of a three-phase transformer coreaccording to the invention will now be described.

Fig. 1 has already been discussed in connection with25 crior art and will not be exclained further.

I 8 0 2 0 '1 0 /d/dV Ο Ο 1 3 Ο 2

In fig. 2 is shown a chree-oftase zransforwer coreaccording co the invention., generally designated 20 . Inits general shape it is similar co Che prior arc trans-former core shown in fit. 1 with a general delta-shapebur is resigned m an entirely different way. -'10

The core is made up of t.nree ring-shaped parts 22, 20,24 comprising several rings. These come in two w„_broad or narrow wherein the narrow rings are made up ofstrips of half the width of the broad rings. Also, theycome in two Heights, low or high wherein the'low ringshave naif the height of the high rings. Unless other-wise stated, these definitions will be used througnoutthis description. The strips are preferably made cotransformer place. 15 Each of the ring-shaped parts 22-24 comprises a broad. c-gc rant ring 22a-24a, respectively, similar co t.aosedescribed with reference to fig. 1. Thus, these ringsform in pairs four of the sides in the hexagonal legs.The remaining rhombs in the legs are built in different u,„£0 ways, see figs. 2a and 2b,

In the first leg 25 in the background, the additionalrhcmbic cross-section is composed of two rhomboids. Thefirst one, designated 2.4b and belonging to ring-shapedpart 24, is a broad low ring. The second one, desig- 25 nated 22b and belonging to ring-shaped part 22, is anarrow high ring.

In cue secoria leg 26 to the right in fig. 2, the addi-tional rhombic cross - section is composed of one rhom-boid and two rhombs. The rhomboid is filled by the car- 30 row high ring 22b belonging to the ring-shaped part 22. ΑΡ ΰ Ο 1 3 Ο 2

The rhombs are filled by two narrow low rings 23b, 23cbelonging to the ring-shaped part 23.

In the third leg 27 to· the left in fic. 2, the addi-tional rhombic cross-section is also composed of one 5 rhomboid and two rhombs. The rhomboid is filled by thebroad low ring 24b belonging to the ring-shaped part 24. The rhombs are filled by two narrow low rings 23b,23c belonging to the ring-shaped part 23. The reasonthat the ring-shaped part 23 comprises two low narrow 10 rings instead of one larger ring is that this largerring can not be both narrow and high, as required inthe left leg 27, and broad and low, as required in theright leg 25. Thus, instead two narrow low rings areused. 15 All upper or lower yokes connecting the legs 25-27 havedifferent snapes but all are built from one basic ringwith a large rhombic cross-section plus one ring with arhombcidal cross-section or cwo rings with a smallrhombic cross-section. This gives all yokes the same )2C total cross-section area.

The rhombic space outside of the basic rings could ofcourse be filled in accordance with a couple of basicprinciples. A second embodiment will now be describedwith reference to figs. 3a and 3b. The core, generally 25 designated 30, has the same general shape as the firstembodiment described above. However, in this embodimentthe core comprises three identical ring-shaped parts32-34, of which the rightmost one 32 will be described.The ring-shaped parts 32-34 are similar to the part 23 30 described in connection with fig. 2. In the first leg35, part 32 comprises two narrow low rings 32b, c

18 0 2 0/10 /d/dV APO 0 1302 wherein ring 22c is wo»md outside of ring 32b. In tnesecc't leg 36, part 3 2 has the two rings 3 2o, 3 2celated one beside toe ocher, see fig. 3 a.

The two other parts 33, 34 are identical· to the firstone 32. Thus, the production of the core can as a rulebe simplified., depending on the production volume, be-cause ail tnr-e ring-shaoed parts 32-34 can be madecron· tee sane mould. A further possibility is to make broad low rings -n.turn toe leg parts 30 degrees, forcing a correct, tingbending of tne yoke parts. The yoke parts then . .- more space and the bending is not so east’ to effect.Making narrow high rings and turning and bending asmentioned is also possible, but difficult. Additionalvariants, including those with smaller divisions, are A core ’with octagonal legs, generally designated 42,will new be described with reference to figs. 4 and 4a.In an octagonal cross-section, see e.g. the back leg45, the sides turn 45 degrees, which means that theyhave a relative angle of 135 degrees to each other.Three rhombs, each with an angle of 45 degrees, thusget space m the innermost edges of the legs of thecore. Outside of these rhombs, two squares are filledby rings with quadratic cross-sections. Finally, arhomb fills the rest cf the octagonal cross-section ofthe leg.

From these,six cross-subsections , three subsectionscompose the cross-section of a profiled ring going totne second leg 46. The remaining subsections compose AP/P/ 01,02081 AP ϋ Ο 1 3 Ο 2 the cross - section of a orofiled ring sci"g co the chordleg 47. There is also a profiled ring connecting thesecond and chord leers 45, 4".

The three rs a_i contact two equal leg pares. A firsc ring 42a, 43a, 44a has a rhom-bic cross - section and the yoke pares bene 15 degrees. Asecond ring 42b, 43b, 44b outside of che firsc ring isquadratic and follows che form of che firsc ring 42a-44a.

Using a solution from che embodiments with hexagonallegs described w7ith reference to figs. 2 and 3, twoouter rhombs comoose the cross-section of an outer rinc wich the yoke parts bent lo degrees. A.lternati velv, two inner rhombs compose an inn er ring but bent SO degrees . The next ring must now give an outer rhomb in one leg 00 o

CM and an inner rhomb an cne other leg and be bent 30degrees. Cne type of profiled ring is co be preferredbecause it is difficult to bend a ring SO degrees andone can not avoid a ring with both an outer rhomb andan inner rhomb.

In part 42, the third ring 42c has a rhombic cross-section in the leg parts and is placed outermost in theback leg 45 but inside the right leg 46. These rhombsof the leg parts are obtained by displacing the outerstrips of the ring to the right at the right leg 46 andto the left at the back leg 45. Furthermore, the legsare turned asymmetrically 30 degrees and the yoke partsare bent accordingly. The ring is given such a circum-ference that 'it will lie outside of the other rrngs.

The final result appears in fig. 4.

Ap ο Ο 13 Ο 2 designated 50, will now tontam ail four rings re co fig. -5. The profiled rings with equal leg parts. A most i 5 0t and a third rmc 50c with 5 mon-door cross-sections m their leg parts are attucned .—· 1«. "* £. ·> .-‘i Ο ,'-*’ r* v·"', ζ; .,., f section. Thus they have the angles 3£, 72, and 1C3 degrees and their yoke parts tent aegress . A iou: *th ring 50d having a rhomboid cross-section with the angle 3S degrees lies mainly ‘J 1C upon me first ring 5/h - . Its leg parts are turned out- wards 24 degrees, taut. mg a 43 degrees bending of its vokss The fourtn ring also causes the yoke parts of me wore ring 5 0c to i tame a larger cow to give stacs. A fide ring SOe has a rhombic cross-section in its let IS parts with the angle Ι- ?! degrees when it lies outside οί the third ring 50c, out the ring has a rhombic stole 72 decrees when it lies outside of the fourth ; unc 50d. The yokes are bent onl\ 12 degrees. The arrows i the figure indicate that the 20 cross-sections 50e bel. >ng to different profiled rings. ) Tnere wi_i aiso ds a or lannel 51 suitable for coding lees. In s.n. slnenric itive embodiment, the channel is filled wich a ring* Th; .3 is an advantage when the rings co-operate by letting f .he magnetic field go between 25 them. The space can e.c ;be disposed of in such, a way that the upper part of the rings 50c obtains new thorn- bit cross - sections witr i the angle 72 degrees, causing the channels 52a and 51 lb to be formed. Further parts oi ring 50c to the right c :an be pushed to ring SOe, which 30 forms the spaces 53a a: id 53b. It is possible to provi „de three-phase transformer cores with even more edges, ί lig. 6 shows a 12-sided core, ΑΡ/Ρ/Ο 1 /0 2081 ΑΡθ 0 1302 generally designated 50. The profiled rings are com-posed of four rings 50a-d with rhombic cross-sectionswith the angles 30, SO, 50, and 120 degrees, which areattached to the 12-sided cross-section and are turned 5 15 degrees. Inside of these rings there are two rings SGe, SOf with rhombic cross-sections with the angles 30and SO degrees, respectively, and turned outward 15degrees. Attached to the fifth and sixth rings 50e, 50fthere is space for a ring 6Cg with a rhombic cross- 1 section with the angle 30 degrees turned outward 45 decrees. Its other leg part is a rectangl e outside of the sixth ring SOf and turned outward 15 degrees . Upon the ring 50d there is space for a ring SOh with a rhom-bic cross-section with the angle 150 degrees and the 15 other leg part is a rectangle attached to ring 63d andoutside ring SOf. The whole cross-section is thenfilled. Yoke parts are separated by giving some widerbows to give space for other yoke parts.

The good properties of these transformer cores can be 20 made even better for some transformer application, seefig. 7. The leakage inductance can easily be increasedby an additional core 29 of strips between the primaryand secondary windings of the transformer. The stripsare brought together at the top and bottom. The strips 25 can be spread around the entire primary winding or be concentrated to one place, making the secondary windingeccentric.

The non-linear magnetic properties of iron result mharmonics in the magnetic fields, voltages and cur- 30 rents. AP/P/0 1/ 0 20 81 AF ο ο 1 3 Ο 2 potent5 on one pnase voi tages, like the third harmon- □ ICS: wv..i xr,lluer*C“O oy a centre leg. Also 5- cornjccns.CIon 01 sc nos oetween tne winnings me. 3

In one emooentem, tne c entre _eg is mace co tnree rec- “angular coles SO from s trips given a height tnree XV oarr.es me av_c.iv, rale on each -other to a quadratic cross - section , see fig, S < This is orsfsxHfalv triBnzu· lar and a custom-made so lution contains poles with a mormcc onoss““SeoOro.m? o £ which three are tut together. co com a cHck.sc wicui m 2 strio edges toward each other 15 in a wave com. ses fio. 5. Three packets are put 00- gethexr with small distan ;es to form a leg with a cross- section approximating a triangle. The ends of the poles are bet; outward to reac 0 the yokes. To make the oends pOSSCCC.6 SpSCSCS O6CWS6C the poles are necessary. The 20 spacers do not influence the magnetic properties b-e- cause one pole from each 913 ~ v* r 9 2 3 · ,Λ 91 Vi -T χ s bent to each yoke. Also the strips are, at least on one side, parallel to the sp tears , A rod. wound cf strios i 0 spiral form or as coils, is 25 useful, especially if zh ~·χ·£ 32Γ3 io fas six’ csds between the centre leg and the y ekes. The spiral can be made wider at the ends to red lh3 3127 CSOS tLO lh.6 XOKSS The flexibility of build ing cores like this is coed and is snown m Zic. lev, Un'S figure shows the core de- 3 0 scribed in connection wx th fig. 4. A major part of the ΑΡ/ΡΖ 01/02081 ma met ux an another in the ieos

ΑΡ υ 0 1 3 0 2 ·, « nrr :hev are ton·: ΟΣ Z.5.2TCTS- rum

With the present invention, in is also possible to pro-vide a three-phase transformer core with lined up legs.This has the advantage that the transformer is narrowerthan with the delta shaped core. This type of trans-former is ideal for placement on e.g. train wagons.

Fig. Ila shows the transverse cross-section of a trans-former with octagonal legs. All legs comprise fourrhombs with an angle of 45 degrees and two squares.Fings running between adjacent legs are shewn in thefigure while those running between the cuter legs arealmost entirely hidden.

In order to make transformer cores of this kind, theleg parts must be bendable and that the yoke parts canbe bent and pass each other. There are several solu-tions, of which one is shown in the figure. The legparts of the rings are bent outward and the yoke partinward or vice versa. The shape of the yoke parts islimited by the limited possibilities of plastic defor-mations but otherwise the yoke parts can have anyshape. The principle shown in fig. 11 is to have sharpbends and straight yoke parts.

The rings can also be placed on each other givingrounded bends in order to save material.

The yokes between the left116 are built up of a ringsection in the leg part, a leg 115 and the centre leg112a with a rhombic cross-ring 112b with a square AP/P/ 0 1, 0 2 0 8 1 AF· ϋ Ο 1 3 Ο 2

rings 112a and 112b fit into the octahedrons close tothe yoke side while the ring 112c tits into the oppos- ing side -

The yeks between the centre leg 116 and the right leg117 can only be placed if the centre leg m the remain-ing positions: 114a-c. The cross-sections of the leftand right legs 115, 11“ are mirror images to the centre leg ill so tna t the rings running in the centre Χ X 3, X S symmetr :o. The inner rings ilia, 11-b have their c los - sst pcs itions in the right leg 117. However, the x x no 114c with a square cross-section in the leg parts runsto toe closest square-snared position in the right leg. 15 The reason behind that is that the ring 113a with asquare cross-section between the outer legs is m anouter position on the yoke parts already present morder to reach the left leg.

The turning of the yokes can be impossible to achieve.20 In an alternative embodiment, a heavily sloping fold is used instead. This is.shown for the ring 114c havingthe shortest yoke. The fold starts at one end of theyoke and ends at the other end, marked by 113a tor thelower yoke and 113b for the upper yoke in fig. 11. 25 Also, one yokes can be subdivided into several narrowrings . AP/P/ ο i / 0 2 0 8 1

Also single-phase transformers will be more efficientif they are given polygonal cross-sections. Fig. 12shows a transformer with an octagonal cross-sec: 30 composed of rings with the same cross-sections as in the three-phase transformers but with the return loops ΑΡυΟ130 2

ocing the closest way outside of the windings. Therings can be transposed and yet given an octagonalcross - sect ion. A small reduction of the amount of platecan e.g. be obtained by looping up to the left of thering looping rightmost in the figure. There must itscross-section be changed to a rhombic form close torectangular form. A core with two legs can be made from the three-phase designs by bending the rings from one leg together to 1 u form only one more leg . A core is shown in fig. 13 with an octagonal cross-sec tion in its legs. The turning of three leg-parts is 45 degrees and the bending is 90 degrees. A ring with a rectangular cross-section and one two rings outside of that ring are not deformed. 15 Cores with hexagonal 1 ecs need onl y three rings made of strips with the same width.

If that octagon edge where three rhomb edges meet, isput innermost in the core, the turnings will only be22.5 degrees except for the rhomb in the middle, which ) 20 must be turned 67.5 degrees. Replacing this rhomb with a ring, with steps approximating the rhomb, is morerealistic and is shown in fig. 14. A further improve-ment is made by letting the strips reach the circle,thus increasing the total cross-section. 25 The segments outside of a polygonal leg can be filledby a thin rhombic ring of a strip with about half thewidth and the full height of the segment and wound toits total width. Folds in the strips along the middleof the rhomb as in fig. 15 make two sides to one flat 30 side giving a triangle, the sides of which are in con-tact with the core. With about 2/3 width and 8/9 AP/P/ 01/020 81 ΑΡ Ο Ο 13 Q 2 2132.^222. di z. z~z s_ one eoc '"z oi 22223 2.222232222205 50222.0 02x35

Ti r r ’T"i .£ ~ C* ,· " V ;·~ 'V- " ,·—\ — .-- .-··' = ,..a,.._ w:d:h _he le3 carts ' ' be given a cross-section snape closer to the shape of a 'io. "i w: d be described as an example with reference to fig. l“a, wherein a tc ansvsrss cross-section of that leg is shown. Innermost., - o. y λ 5. X 3 X 2. XL O S 2. *7 3 02 3 Ci SGI of tell wrath ano to a height of 9% of its width.. cnino a circumscribed circle, see .-our o: the sen segments Hbive 0 0-.2.30 WOOD. 203-5^3 0 00 w·^ o as of the assembled core can till the other segments.. O j, 4 .„,,» -- -J - „ - „ «, -,1 g-a,-5 - ‘ '· -— ·· ^P*®S· on one outer sires ot toe hexagons . © U Another embodiment is she wn in fig. 17b, wherein the .. <£ a. ov croaaer strips m one o c i? e x* 5ΟΓΠ3 Οι. 0223 dCv’SHC SC6 S CO one inventive transtermer coirs hxav3 3. Io* 3 3. civ been ins rrcionsd. Among the other advantages can be mention ed: lower no load losses, less weight, less volume, lows r electrical leakage, a reduc- cion of harmonics due to the symmetry of the phases of t“ H ii 7“ m v ς». ϋ - w* H .x c: *“ v h*- 'v* rh ,er, easy maintenance etc . ?X"3 0 3ΧΌ'βΟ. 3Π03θόθΓΠ3Χ10, 5 02 a transformer core acccrt ..g the invention have been described. The person ski APO 0 1302 in che arc realises chac chess car. he varied wimr cnescope cc che claims. AP,T/ 01/02081

Claims (4)

1. ΑΡ ο Ο 13 Ο 2 ί S 5 , W~S ft r a c t e r i s e d in c ft a cterisec erise id ftC; AP/P/ 0 1 10 2 0 8 1 characterised by

   5> * li ) ---.- . . C Ί ΑΡνΟ130 2 2a, 34a)

   sec:n assembled whereby a chree-ohase ir="s:cr.”er cere withthree lees wire hexagonal cross-sections is corned.
2. 6. A transformer core according to claim 2, characterised in that it comcrises seven r tngs A transformer core accordinc to claim 6, AP/PZ 0 1 > 0 2 0 8 1 2G characterised by (22a), a second (23a) and a third )24a) ring wcunc crom series a/—wi. a — __ f said rings oeinc rhoroic with two U- CX J. J. - o > one cross-sections c: angles of 60 degrees, said first, second an25 rings forming yoke parts together forming a triangle, a fourth ring (24b) wound from a strip of said firstwidth to a second height essentially corresponding tohalf the first height, said fourth ring having rhomboi- 0 SHEET Ar :os “ i ο π β d ο AP/P/ 0 7/02081 characterised in t h a

   • SHcEI APO 0 1302 C iL - 3 - 3 ' S — “ 3 36 3 C* - p = r_~ art novae towards ~ ~ / its teg par_s ano oet.n: a tntre ring ‘-i^z; nav; .ng rncmoic cross-sections in its leg parts, a first leg tart havino 43 decrees Ivino mainly on sate rtrst r; .ng (42a; and a second leg part having 133 degrees iyir \g on said second ring (42b), -j saic rtrst, second ano third orof''- r-.nos beinc assert- bled wherebv a three-oh ‘SCi - ς “ *- '* i- h legs with ootagenai orc :ss-sscttons is formed. Ί P- 2, - -- ς -,ς - --η O V core according to claim 1, characterised in that said lees have a cross-seczicr. wizh 11. .-. transformer core according to claim 10, characterised b v a f^rst, a second, and = υ Π d C ** O S ό Cj / ° c C h comprising five rings (50a-e) with two leg parts and two yoke parts, wherein 20 a first rinc (50a) havi no rhombic cross-sections in its leg parts with at angle of 36 degrees, ΑΡ/Γ/ 0 1 0 2 0 8 1 a second ring (50b) hav ing rhombic cross-sections in its leg parts with an a: ngle of 72 degrees, a third ring (50c) havi: ng rhombic cross-sections in its 25 leg parts with an angle of 103 degrees, a fourth ring (5Cd) hav. ing rhombic cross-sections in its leg parts with at angle of 36 degrees and lying j SHEET APO 0 1302 rees, arc 5, firm ring )50e) hiring rhcmbic crcss-isc:io.~s „n itsleg tarts «r:h m angle of 144 degress wner it loss or. 5 me of arc root (50c) coo rhombic cross-section mom anangle cf 72 degrees when it lies outside the fcurmring )10d), end a channel (51) suitable for coclmg oneleg outs_ne ci the fmm ring (50e) , sate first, second and more profile rings being assert-10 bled whereby a three-chase transformer core with corse ” ϋ r” ~ ,' ‘ "» -» CJ - o. ;'*· 0 ’ 5) — -v — —J 11. transformer core according oc claim 11, characterised by cooling channels (52a, 52b. 52a, 53 b) caused by giving the outer part of the 15 more ring (50c) a rhcmbic cross-section worn an. anglecf 3 2 regress and by nispiacing another outer leg partof the thin ring tewan the fifth ring (50a) whet itgoes within me ccmplsts leg. 1.3. A transformer core according to claim 10, 20 characterised by multi-edged cross-sectionsof them lags and profits rings comprising a firstclutter of rings with rhombic cross-sections withdifferent angles but in their leg parts turned the sameangle and attached to the multi-edged cross-sect ton, 25 and inside a second cluster of rings with rhombic cross-section with different angles, but in their tegparts turned the same angle and attached to the tirstcluster and so on until innermost there arises spacefor rings, which in one of their leg parts is given a AP/PZ 0 7/0 2091 Aiulldeu SHEET AP001302 f characterised in that ail rings have arhombic . cross-section with twe angles of 52 degrees andtwo angles of 120 degrees. • ΣΟ2ΓΣΠβ2Γ CO-6 3.( 10 20 characterised by an additiona. strips tetween winnings orougntthe br·· —cf the core. arm
3. 15. A transzemer core accorcznc to c_azm -, characterised by an additional core in thecentre line of at least one strip pole, and if many,arranged three and three in a package (figs. 8 and 9),which teles are bent to each voke.
4. 17. A transformer core according to claim 1, characterised in that segments betweenthe cross-sections of the legs and a circumscribedcircle are tartly filled bv thin rincs and/or slightlybroader series. ΑΡ/Γ/ o 110 2 0 81 D SHEET