US3581258A - Electromagnetic wiring system of interlinked coils particularly suitable in a current transformer for high voltages - Google Patents

Abstract

An electromagnetic energy transforming device particularly suitable in a current transformer for high voltages and similarly interlinked coils comprising at least one core; at least one coil threaded through said core; said core having a closed symmetrical geometrical z-y shape of a z-y longitudinal cross section with at least two core legs in parallel and at least one core bar interconnecting said legs; said core having a x-y symmetrical cross section perpendicular to the length of said core substantially elongated, with a longer ''''x'''' axis and a shorter ''''y'''' axis and a ''''z'''' axis perpendicular to said x and y axes; said at least one core bar being symmetrically gradually twisted relative to said core legs with the core ''''x'''' axis being parallel to the ''''z'''' core axis of said at least two core legs in the center of said core bar between said core legs; the surface of said core bar adjacent the surface of said coil bar being of a shape closely mating with said surface of said coil bar in three dimensions.

Description

United States Patent [72] Inventor Friedrich Raupach FOREIGN PATENTS l MeSsWandler-Bau GmbH, m s 671,627 5/1952 Great Britain 336/234 Strum Bambers, Germany 220,587 7 1942 Switzerland 336 221 2933 13 1969 445,631 2/1968 Switzerland 336/234 l e [45] Patemed May 25, 1971 Primary Exammer-Thomas J. Kozma Attorney-Otto John Munz [54] ELECTROMAGNETIC WIRING SYSTEM 0F INTERUNKED COILS PARTICULARLY SUITABLE ABSTRACT: \n electromagneuc energy transforrmng device IN A CURRENT TRANSFORMER FOR HIGH particularly suitable in a current transformer for high voltages VOLTAGES and similarly interlinked coils comprising at least one core; at 32 Claims, 14 Drawing 18$ least one coil threaded through said core; said core having a closed symmetrical geometrical z-y shape of a z-y longitu- [52] US. Cl 336/173, dina] cross section with at least two core legs in parallel and at 336/175 336/212 336/223 336/225 336/234 least one pore bar interconnecting said legs; said core having a [51] Int. Cl 01140/06 symmetrical cross section fierpendicular to the length of [50] Field Of Search 336/173, Said core substantially elongated with a longer i and a shorter y axis and a z axis perpendicular to said at and y 229 axes; said at least one core bar being symmetrically gradually twisted relative to said core legs with the core'ffx axis being [56] References Cited parallel to the z core axis of said at least two core legs in the UNITED STfATES PATENTS center of said core bar between said core legs; the surface of 1,425,091 8/1922 Hol'ellck 336/234X said core bar adjacent the surface of said coil bar being of a 3 2/1949 obelt 336/225x shape closely mating with said surface of said coil bar in three 2,838,732 6/1958 BlOWn 336/225X dimensions a 16 17 20 IIrII 'PATENTED HAY25 |97| SHEET 1 UF 3 9-1 PRIOR ART ig.2 PRIOR ART PRIOR ART INVENTOR FRllilJR [CH RA LIP/\Ql-l A ORNEY PATENTEU M2519?! 3581; 258

sum 2 or 3 INVENTOR FRIEDRICH RAUPACH ATTORNEY PATENTED W25 Ian I SHEET 3 OF 3 FIG 8 INVENTOR FRIEDRICH RAUBACH ORNEY ELECTROMAGNETIC WIRING SYSTEM OF INTERLINKED COILS PARTICULARLY SUITABLE IN A CURRENT TRANSFORMER FOR HIGH VOLTAGES THE FIELD OF THE INVENTION THE PRIOR ART The high-voltage current transformers which are frequently used particularly for measuring great currents and which comprise an annular iron core carrying the secondary winding and a U-shaped primary winding extending therethrough are generally accommodated in an insulating jacket being filled with an insulating medium, for example in a hollow porcelain supporting insulator with a grounded metallic foundation and a metallic covering hood having a high voltage potential.

SUMMARY OF THE INVENTION The present invention relates to a current transformer, particularly for highvoltages, with an annular bandaged coil form consisting of the closed iron core provided with the secondary winding, and with a U-shaped bandaged coil form constituted by the primary winding and extending through the core window, and shows a way toward obtaining a considerable reduction of the insulating jacket diameter and hence an essential 7 reduction in the costs for such a current transformer.

In accordance with the present invention, this object is obtained in that at least one of the two aforementioned coil forms, viewed in cross section, has the configuration of an ellipse or of an ellipselilte rectangle which varies, with regard to the path ofthe main axis thereof, in such a manner that at that point of the coil form where it is positioned between the parts of the other coil form enclosing it the main axis of the ellipse of the cross section extends parallel to the longitudinal central axes of the two legs of the U-shaped coil form, whereas at those points which are positioned on both sides of the part of the other coil form being enclosed thereby the main axis of the ellipse of the cross section extends parallel to that part.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate the same or equivalent parts throughout the several figures thereof and wherein:

FIGS. I through 3 represent the prior art;

FIG. I being a schematic illustration partly in longitudinal cross section and partly in elevation;

FIG. 2 a cross-sectional view and a plan view respectively of portions of FIG. 1;

FIG. 3 a possible improvement over the prior art, disclosing a deficiency of such an arrangement;

FIGS. 4a, 4b and 4c are schematic cross-sectional views of an embodiment of the present invention;

FIGS. 5a, 5b and 50 show a further improvement on the embodiment shown in FIGS. 4;

FIGS. 60, 6b, 6c and 6d show the present invention s development of a part of the new device;

FIG. 6a is a perspective cross section view analogous to the cross-sectional views of FIGS. 4b and 5b in a cutaway;

FIG. 6b is a perspective view corresponding to that of FIG. 60 from a different angle with a portion of the part cut away;

FIG. 60 is a perspective cross-sectional view through a portion of the device of the present invention analogous to the view of FIG. 50;

FIG. 6d is a perspective view of a section of the device of the present invention;

FIG. 7a is a schematic longitudinal cross-sectional view;

FIG. 7b is a side view;

FIG. 70 is a top plan shown in 60 and d;

FIG. 8 is a perspective view of a component part of a practical embodiment of the invention;

FIG. 9 is a perspective view with a portion cut away of an improvement of another component part of the present invention; and

FIG. 10 is a schematic view showing a three-dimensional arrangement of a combination of parts of FIGS. 6a and b with FIG. 9.

view of the construction of a part DESCRIPTION OF THE PREFERRED EMBODIMENTS The improvement by the present invention is explained in the following on hand of FIGS. I and 2, which represent conventional prior art currenttransformers.

In FIG. 1, the insulating jacket 11 and the annular iron core 12 are shown provided with the secondary winding and with the insulating bandage 13 thereof, in a longitudinal crosssectional view while the U-shaped primary winding 14 together with the insulating bandage 15 thereof is shown in elevation.

FIG. 2 is a cross-sectional view through the insulating jacket 11 and the bandage iron core 12 as well as a top plan view of the bandaged primary winding 14. It is evident therefrom that a considerable portion of the inner space of the insulating jacket is filled not with the active transformer parts but with the insulating medium.

The inventor found that the costs for such a current transformer could be lowered considerably by reducing the diameter of the insulating jacket as well as the amount of insulating material since particularly the share of the insulating jacket is very high with respect tothe total costs. Such a reduction of the diameter of the insulating jacket cannot be achieved when making use of a known construction wherein both the bandaged iron core 12 and the bandaged primary winding 14 have an ellipse-shaped cross section, as illustrated in FIG. 3. While the outer contours of the active transformer parts adapt to the shape of the insulating jacket wall more readily than is the case when the iron core and the primary winding have a circular cross section, as shown in FIGS. 1 and 2, the diameter of the iron core and the distance of the two legs of the U-shaped primary winding however must then be made correspondingly wider.

References to a cross section in the form of an ellipse and to the main axis" thereof are intended to indicate within the framework of the present invention not only a cross section in the form of an ellipse in the purely mathematical sense, but generally a cross-sectional shape similar to an ellipse which has a longer axis in one direction than in the other direction at right angle thereto.

FIGS. 40, 4b and 4c show an embodiment of the current transformer in a cross-sectional view and in two different longitudinal cross-sectional views, respectively, and are limited to the annular coil form consisting of the iron core provided with the secondary winding therein, constructed according to the teaching of the present invention. The iron core 16 carrying the secondary winding is shown here as well as the insulating bandage 17, the U-shaped primary winding 18, the insulating bandage thereof 19, and the insulating jacket 20. The bandaged iron core 16 with the bandage 17 thereof, when viewed in cross section, has approximately the configuration of an ellipse and is so provided that at the point 21 where the iron core is positioned between the leg portions 19a and 19b of the U-shaped primary coil form 18, 19, these leg portions enclose the iron core, and at the diametrically oppositely positioned point 22, the main axis of this ellipse extends parallel to the longitudinal central axes of the two leg portions 19a and 19b of the U-shaped coil form. The points 23 and 24 of the bandaged iron core l6, 17 are positioned on both sides of the bent portion 19c and are enclosed by the U-shaped coil form. The main axis of the cross section of the ellipse extends parallel to this part of the U-shaped coil form 18, 19; that is horizontally in the arrangement of the transformer parts as shown, and specifically in a direction perpendicular to the central plane of the iron core.

In the further embodiment of the invention, schematically illustrated in FIGS. a, 5b and 50, both coil forms, i.e. also the U-shaped coil form constituted by the primary winding and the bandage thereof are shown constructed according to the teaching of the present invention. In this case, the primary winding 25 and 26 is the bandage thereof. The bandaged iron core 16, 17 is provided in the same manner as has been described with reference to FIGS. 4a, 4b and 4c. The points 21, 22, 23 and 24 correspond to the points identified with the same reference numerals in FIGS. 4a, 4b and 4c. Accordingly, in this embodiment, the U'shaped coil form 25, 26 when viewed in crosssection also has approximately the shape of an ellipse andis so provided that the main axis of the ellipse of the cross section thereof extends parallel to the longitudinal central axes of the two leg portions 26a, 26b of the U-shaped coil form at the point 27 where that coil form is positioned between the enclosing or surrounding parts of the other coil form 16, 17; in the vertical direction in the arrangement of the transformer elements as illustrated. In the area of the two leg portions 26a, 26b which are positioned on both sides of the part (at 21) of the other coil form 16, 17 enclosed or surrounded by the U-shaped form, the main axis of the ellipse of its cross section extends parallel to the respective part of the coil form 16, 17, (at 21), i.e. horizontally, and specifically in a direction perpendicular to the central plane of the iron core.

A comparison of FIGS. 4a and 5a with FIGS. 2 and 3 clearly will elicit that even when constructing only one of the coil forms in accordance with the teaching of the present invention, and assuming in all instances the same cross-sectional dimensions of the active transformer parts or elements, the diameter of the insulating jacket is considerably smaller than it is in the systems of the prior art, and that a significant reduction in the diameter is obtained when both coil forms are provided as proposed by the present invention. It is therefore readily apparent that, by the improvements of the present invention, the costs of a current transformer with a U-shaped primary winding can be considerably lowered. A saving in costs will be obtained also if the current transformer is made not on the basis of the insulating jacket construction but rather with a pot construction, i.e. with a metal pot containing the active parts and with a bushing or lead-in insulator being thereon. In this case, the amount of the insulating material required is correspondingly decreased.

In the two embodiments of the present invention according to FIGS. 4 and 5, the primary winding consists only of a tubular conductor or a round bar 18 and, respectively, of a flat conductor 25 having a rectangular cross section which penetrates or extends only once through the core window. In accordance with FIG. 8, the primary winding may consist also of a tube 18 and either one or several U-shaped conductors are accommodated, insulated in the tube, connected either in series by means of connecting pieces disposed above the U- shaped coil form, or guided to a changeover device being disposed above the active transformerlparts and by means of which they may be selectively connected either in series, parallel or series-parallel. An analogous arrangement is also possible when the flat conductor 25 shown in FIG. 5 consists of several individual conductors insulated with respect to each other and bent in a U-shape. These conductors are connected in series by means of connecting pieces or guided to the changeover device. In this manner the current transformers provided as proposed by the present invention may be constructed also as winding transformers which may be changed over or converted, if desired, on the primary side in a ratio of 1:2 or 1:2:4.

FIGS. 60, 6b, 6c and 6d show in a simple manner the shape of the iron core and of the primary winding of the current transformer apparent from FIGS. 4 and 5. FIG. 6a is a perspective cross-sectional view through the iron core 16 analogous to the cross section shown in FIGS. 4b and Sb, and

FIG. 6b is an analogous view of half of the iron core having been cut away. The iron core consists of several, for example three, separate core parts 16a, 16b and 16c being preferably wound from tape which have different window apertures and which are so provided and arranged that within the area of the point enclosed or surrounded by the U-shaped coil form and at the diametrically oppositely positioned point, 21 and 22 respectively in FIGS. 4 and 5, the core parts are superimposed whereas at the point 23 and at the diametrically oppositely positioned point 24 they are located side by side. If the core parts 16a, 16b and 16c are provided essentially in a circular fashion, they have approximately the same diameter between the points 23 and 24, but not between the points 21 and 22; in the latter case the diameter of the core part 1611 is smaller than that of the core part 16b and the diameter of the latter is, in turn, smaller than that of the core part 160. In many instances, it will be advisable to provide the individual core parts with an oval configuration, as has also been assumed in FIGS. 6a and 6b, so that they extend in a rectilinear fashion over a certain path at the points 23 and 24 and so that accordingly the annular coil form will obtain an oval configuration. When assembling the iron core, one proceeds expediently in such a manner that the core part 16b is initially slid over the smallest core part 160, rotated about and subsequently turned into the position illustrated in FIG. 6. The third core part 16:: is thereupon applied and put in position in a corresponding manner.

. In the case of a current transformer having only a single iron core, the core consisting of the core parts 16a and 16b and is provided with the secondary winding and thereafter with an insulating bandage, which has been omitted in FIG. 6 only for the sake of greater clarity. In so-called multiple core current transformers, i.e. current transformers having several iron cores each carrying one secondary winding (measuring core, relay core), for example each of the individual cores 16a, 16b and 16b will be equipped with one secondary winding. These cores thus comprising secondary windings are then composed and assembled as described above on the basis of FIGS. 6a and 6b to the coil form identified with reference numerals 16, 17 in FIGS. 4 and 5.

FIG. 60 is a perspective cross-sectional view through the primary winding 25 analogous to the cross section shown in FIG. 50 and illustrates how the primary winding is positioned with regard to the iron core shown in FIGS. 6a and 6b. FIG. M is an analogous perspective view of the cutoff half of the primary winding 25. The two upwardly directed leg portions of the U are cut off in these figures. The primary winding consists, for example, of three conductors 25a, 25b and 250 having an approximately quadrangular cross section. These conductors are rotated in a threaded fashion, so that within the area of the window of the iron core 16 they are superimposed with respect to .each other but extend next to each other in a respectively inverse sequence at the point 21 on both sides of the iron core and further in the two leg portions of the U- shaped primary coil form. In the interest of greater clarity the insulating bandage has not been. shown in FIGS. 6c and 6d. In the case of a single-core transformer, the individual conductors 25a, 25b and 250 can rest against each other without insulation since they constitute jointly the U-shaped primary conductor penetrating only once through the core window. They may also be insulated, however, with respect to each other and connected in series, or the ends thereof may be extended or guided to a changeover device in the case of a winding current transformer. which may be adapted to be changed over, switched over or converted, on the primary side, if desired.

After providing the iron core 16 comprising the secondary winding with the required insulating bandage 17, the primary winding 25 which has likewise been previously equipped with the insulating bandage 26 thereof may be introduced into the core window with a threaded rotation, and brought into the correct position with respect to the coil form 16, 17.

A further embodiment relative to the construction of the iron core 16 is schematically illustrated in FIGS. 7a7c: FIG.

7a is a longitudinal cross section view; FIG. 7b is a side view, and FIG. 70 is a top plan view thereof. The iron core has three approximately annular core parts 16d, 16c and 16f which have different window apertures and are so provided and arranged that they are superimposed with respect to each other only within the area 21 (see FIGS. 4 and 5) at the point where the iron core is enclosed or surrounded by the U-shaped primary winding, while being positioned side by side in the areas 23, 24 and 22. Optionally, the individual cores are made of stacked or layered approximately annular sheets and preferably are brought into the shape apparent from FIG. 7 relatively easily by bending the upper portion of the core portion 16f having the greater aperture and the upper portion of the core portion 16d having the next smaller aperture into the plane of the core portion l6e having the smallest aperture, as is particularly distinctly visiblein FIG. 70. This construction of the iron core affords the same advantages as the structure of the iron core apparent from FIGS. 4, 5 and 6, plus the additional advantage of a reduction in structural height of the transformer; its con struction, however, is more complicated than the construction of the iron core shown in FIGS. 6a, 6b.

For the purpose of simplification of claim drafting, FIGS. 6a and 8 provide the two Carthasian coordinate systems for the core and current conductors respective. The structure shown in FIG. 8 exemplifies a modified core form being generally U- shaped. Leads would necessarily connect the free ends.

It should be understood, of course, that the foregoing disclosure relates only to preferred embodiments of the invention and that it is intended to combine complementary parts of the several embodiments of the present invention shown, with each other and/or with portions of conventional magnetic wiring systems. Thus, multiple core parts may be provided to form a multiple core current transformer wherein each core part has a separate secondary winding. This type of assembly is disclosed in Austrian Pat. No. 192,501 of Oct. 1957.

Various modifications are contemplated and may be obviously resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter defined by the appended claims.

Iclaim:

1. An electromagnetic energy transforming device z-suitable in a current transformer for high voltages and similarly interlinked coils comprising: at least one core; at least one coil threaded through said core; said core having a symmetrical geometrical z-y shape of a z-y longitudinal cross section with at least two core legs in parallel and at least one core bar interconnecting said legs; said core having a x-y symmetrical cross section perpendicular to the length of said core substantially elongated, with a longer x axis and a shorter y axis and a z" axis perpendicular to said x and y axes; said at least one core bar being symmetrically gradually twisted relative to said core legs with the core 1: axis being parallel to the z" core axes of said at least two core legs in the center of said core bar between said core legs.

2. An electromagnetic energy transforming device as claimed in claim I, said elongated x-y core cross section being substantially oblong.

3. An electromagnetic energy transforming device as claimed in claim I, said elongated x-y core cross section being an ellipse. v

4. An electromagnetic energy transforming device as claimed in claim 1, said elongated x-y core cross section being a plane-curve.

5. An electromagnetic energy transforming device as claimed in claim 1, said z-y core shape characterized as U- shaped.

6. An electromagnetic energy transforming device as claimed in claim 1, said z-y core shape being a core ring.

7. An electromagnetic energy transforming device as claimed in claim I, said z-y shape being a core oval.

8. An electromagnetic energy transforming device as claimed in claim 1, said z-y shape being a core polygon.

9. An electromagnetic energy transforming device as claimed in claim I particularly suitable for a relay, said z-y core shape having at least one core gap in the cross section of said core.

10. An electromagnetic energy transforming device as claimed in claim I, said at least one core being a plurality of cores. 11. An electromagnetic energy transforming device as claimed in claim 1, wherein said at least one core is a plurality of cores in a circular core stairway assembly of pairs of the core legs, said core legs axially clamped together as a single core unit, the pair of core legs and the core bar of each outwardly successive core exceeding in length the length of the previous pair of core legs and core bar.

12. An electromagnetic energy transforming device as claimed in claim 1, wherein said at least one core is a plurality of cores in an assembly of said cores as a core unit mounted with one core leg of each core superimposed in sequence in a first plane and with the second core leg of each core superimposed in sequence in asecond core plane, said second core plane being perpendicular to said first core plane.

13. An electromagnetic energy transforming device as claimed in claim 11, the area of each core cross section remaining constant throughout the core length.

14. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is oblong.

15. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is plane-curve.

16. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is an ellipse.

17. An electromagnetic energy transforming device as claimed in claim 1, wherein the. exterior appearance of the coil is U-shaped.

18. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior shape of the coil is ringlike.

19. An electromagneticenergy transforming device as claimed in claim 1, wherein the exterior shape of the coil is oval.

20. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior shape of the coil is polygonal.

21. An electromagnetic energy transforming device as claimed in claim 1, wherein at least one said coil comprises at least one half-turn surrounding a core.

22. An electromagnetic energy transforming device as claimed in claim 1, said at least one coil comprising at least one insulated conductor.

23. An electromagnetic energy transforming device as claimed in claim I, said at least one coil being a plurality of conductors in a circular stairway assembly of pairs of conductor legs, said conductor legs axially clamped together as a single coilunit, the pair of conductor legs and the conductor bar of each successive conductor exceeding in le ngth the length of the previous pair of conductor legs and conductor bar.

24, An electromagnetic energy transforming device as claimed in claim I, said at least one coil being a plurality of conductors in an assembly of said conductors as a conductor unit mounted with one one conductor leg of each conductor superimposed in sequence in a first core plane and with the second conductor leg of each conductor superimposed in sequence in a second core plane, said second conductor plane being perpendicular to said first plane conductor.

25. An electromagnetic energy transforming device as claimed in claim 1, the cross-sectional area of the coil remaining constant throughout its length.

26. An electromagnetic energy transforming device as claimed in claim 1, wherein the surface of said core bar adjacent the surface of said coil is of a shape closely mating with the surface of said coil.

27. A current transformer, particularly for high voltages, comprising an annular bandaged coil form having a closed iron core, provided with a secondary winding, and a U-shaped bandaged coil form serving as a primary winding extending through the core window,

characterized in that at least one of said two coil forms,

viewed in cross section, has an oblong configuration which varies in such a manner with regard to the path of the main axis thereof that, at the point of the coil form where it is positioned between the parts of the other coil form enclosing or surrounding it, the main axis of the cross section extends parallel to the longitudinal central axes of the two legs of the U-shaped coil from whereas, at the points which are positioned on both sides of the part of the other coil form being surrounded or enclosed thereby, the main axis of the cross section extends parallel to that part.

28. A current transformer according to claim 27 characterized in'that the iron core situated in the annular coil form consists of several separate core parts which have different window apertures and are so provided and arranged that within the area of the point enclosed or surrounded by the U-shaped coil form and at the diametrically oppositely positioned point of the annular coil form the core parts are superimposed, viewed in the direction of the path of the two legs of the U-shaped coil form, whereas they are positioned side by side at the points situated on both sides of the part of the U-shaped coil form being enclosed or surrounded by the annular coil form,

29. A current transformer according to claim 27 characterized in that the ion core situated in the annular coil form consists of several separate core parts which have different window apertures and are so provided and arranged that, viewed in the direction of the path of the two legs of the U-shaped coil form, they are superimposed only within the area of the point being enclosed or surrounded by the U-shaped coil form while being positioned side by side in the remaining area of the annular coil form.

30. A current transformer according to claim 27 characterized in that the primary winding constituting the U-shaped coil form consists of several conductors being bent in a U-shaped manner which, viewed in the direction of the extension of the two legs of the U-shaped coil form, are superimposed within the area of the point enclosed or surrounded by the annular coil form whereas they extend side by side in the two legs of the U-shaped coil foml in a respectively inverse sequence so that the long sides of the two legs face each other.

31. A current transformer according to claim 30 characterized in that the U-shaped bent conductors are insulated with respect to each other and are either connected in series by means of connecting pieces disposed above the U-shaped coil form, or guided to a changeover device disposed above the U-shaped coil form by means of which they may be switched over selectively in series, in parallel, or series-parallel.

32. A current transformer according to claim 28 characterized in that the core parts constitute a multiplecore current transformer each core part provided with a separate secondary winding.

Claims (31)

1. An electromagnetic energy transforming device z-suitable in a current transformer for high voltages and similarly interlinked coils comprising: at least one core; at least one coil threaded through said core; said core having a symmetrical geometrical z-y shape of a z-y longitudinal cross section with at least two core legs in parallel and at least one core bar interconnecting said legs; said core having a x-y symmetrical cross section perpendicular to the length of said core substantially elongated, with a longer x'''' axis and a shorter y'''' axis and a z'''' axis perpendicular to said x and y axes; said at least one core bar being symmetrically gradually twisted relative to said core legs with the core x'''' axis being parallel to the z'''' core axes of said at least two core legs in the center of said core bar between said core legs.

2. An electromagnetic energy transforming device as claimed in claim 1, said elongated x-y core cross section being substantially oblong.

3. An electromagnetic energy transforming device as claimed in claim 1, said elongated x-y core cross section being an ellipse.

4. An electromagnetic energy transforming device as claimed in claim 1, said elongated x-y core cross section being a plane-curve.

5. An electromagnetic energy transforming device as claimed in claim 1, said z-y core shape characterized as U-shaped.

6. An electromagnetic energy transforming device as claimed in claim 1, said z-y core shape being a core ring.

7. An electromagnetic energy transforming device as claimed in claim 1, said z-y shape being a core oval.

8. An electromagnetic energy transforming device as claimed in claim 1, said z-y shape being a core polygon.

9. An electromagnetic energy transforming device as claimed in claim 1 particularly suitable for a relay, said z-y core shape having at least one core gap in the cross section of said core.

10. An electromagnetic energy transforming device as claimed in claim 1, said at least one core being a plurality of cores.

11. An electromagnetic energy transforming device as claimed in claim 1, wherein said at least one core is a plurality of cores in a circular core stairway assembly of pairs of the core legs, said core legs axially clamped together as a single core unit, the pair of core legs and the core bar of each outwardly successive core exceeding in length the length of the previous pair of core legs and core bar.

12. An electromagnetic energy transforming device as claimed in claim 1, wherein said at least one core is a Plurality of cores in an assembly of said cores as a core unit mounted with one core leg of each core superimposed in sequence in a first plane and with the second core leg of each core superimposed in sequence in a second core plane, said second core plane being perpendicular to said first core plane.

13. An electromagnetic energy transforming device as claimed in claim 11, the area of each core cross section remaining constant throughout the core length.

14. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is oblong.

15. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is plane-curve.

16. An electromagnetic energy transforming device as claimed in claim 1, wherein said coil has a cross section that is an ellipse.

17. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior appearance of the coil is U-shaped.

18. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior shape of the coil is ringlike.

19. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior shape of the coil is oval.

20. An electromagnetic energy transforming device as claimed in claim 1, wherein the exterior shape of the coil is polygonal.

21. An electromagnetic energy transforming device as claimed in claim 1, wherein at least one said coil comprises at least one half-turn surrounding a core.

22. An electromagnetic energy transforming device as claimed in claim 1, said at least one coil comprising at least one insulated conductor.

23. An electromagnetic energy transforming device as claimed in claim 1, said at least one coil being a plurality of conductors in a circular stairway assembly of pairs of conductor legs, said conductor legs axially clamped together as a single coil unit, the pair of conductor legs and the conductor bar of each successive conductor exceeding in length the length of the previous pair of conductor legs and conductor bar. 24, An electromagnetic energy transforming device as claimed in claim 1, said at least one coil being a plurality of conductors in an assembly of said conductors as a conductor unit mounted with one one conductor leg of each conductor superimposed in sequence in a first core plane and with the second conductor leg of each conductor superimposed in sequence in a second core plane, said second conductor plane being perpendicular to said first plane conductor.

25. An electromagnetic energy transforming device as claimed in claim 1, the cross-sectional area of the coil remaining constant throughout its length.

26. An electromagnetic energy transforming device as claimed in claim 1, wherein the surface of said core bar adjacent the surface of said coil is of a shape closely mating with the surface of said coil.

27. A current transformer, particularly for high voltages, comprising an annular bandaged coil form having a closed iron core, provided with a secondary winding, and a U-shaped bandaged coil form serving as a primary winding extending through the core window, characterized in that at least one of said two coil forms, viewed in cross section, has an oblong configuration which varies in such a manner with regard to the path of the main axis thereof that, at the point of the coil form where it is positioned between the parts of the other coil form enclosing or surrounding it, the main axis of the cross section extends parallel to the longitudinal central axes of the two legs of the U-shaped coil from whereas, at the points which are positioned on both sides of the part of the other coil form being surrounded or enclosed thereby, the main axis of the cross section extends parallel to that part.

28. A current transformer according to claim 27 characterized in that the iron core situated in the annular coil form consists of several separate core paRts which have different window apertures and are so provided and arranged that within the area of the point enclosed or surrounded by the U-shaped coil form and at the diametrically oppositely positioned point of the annular coil form the core parts are superimposed, viewed in the direction of the path of the two legs of the U-shaped coil form, whereas they are positioned side by side at the points situated on both sides of the part of the U-shaped coil form being enclosed or surrounded by the annular coil form.

29. A current transformer according to claim 27 characterized in that the ion core situated in the annular coil form consists of several separate core parts which have different window apertures and are so provided and arranged that, viewed in the direction of the path of the two legs of the U-shaped coil form, they are superimposed only within the area of the point being enclosed or surrounded by the U-shaped coil form while being positioned side by side in the remaining area of the annular coil form.

30. A current transformer according to claim 27 characterized in that the primary winding constituting the U-shaped coil form consists of several conductors being bent in a U-shaped manner which, viewed in the direction of the extension of the two legs of the U-shaped coil form, are superimposed within the area of the point enclosed or surrounded by the annular coil form whereas they extend side by side in the two legs of the U-shaped coil form in a respectively inverse sequence so that the long sides of the two legs face each other.

31. A current transformer according to claim 30 characterized in that the U-shaped bent conductors are insulated with respect to each other and are either connected in series by means of connecting pieces disposed above the U-shaped coil form, or guided to a changeover device disposed above the U-shaped coil form by means of which they may be switched over selectively in series, in parallel, or series-parallel.

32. A current transformer according to claim 28 characterized in that the core parts constitute a multiple-core current transformer each core part provided with a separate secondary winding.

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