US3691492A

US3691492A - Choke

Info

Publication number: US3691492A
Application number: US206828A
Authority: US
Inventors: Walter Muller
Original assignee: Transformatoren Union AG
Current assignee: Transformatoren Union AG
Priority date: 1970-12-10
Filing date: 1971-12-10
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

A choke for high voltage mains. The choke includes two identical partial windings having turns wound in opposite directions to one another. The magnetic circuit includes a ferromagnetic upper yoke and a ferromagnetic lower yoke. The upper ends of the partial windings are electrically connected to the upper yoke to which is applied the full potential to be applied to the choke and the lower ends of the partial windings are electrically connected to the lower yoke. The magnetic circuit includes two magnetic core members extending between the upper yoke and the lower yoke. The partial windings are each disposed respectively about individual ones of the magnetic core members. Two insulating columns each having an upper opening and a lower opening surround respectively individual ones of the partial windings. Two shielding members are positioned respectively about individual ones of the yoke members. The shielding members and the yoke members are effective to close off the upper and lower openings of the insulating columns from space outside of the choke.

Description

United States Patent Miiller 51 Sept. 12, 1972 1' CHOKE FOREIGN PATENTS OR APPLICATIONS [72] Inventor: Walter Miiller, Schwabach, Ger- 732,281 2/1943 Germany ..336/184 many [73] Assignee: Transformatoren Union Aktienreesellschafi, Biased-Be? a statt, Germ any [22] Filed: Dec. 10, 1971 [21] Appl. No.: 206,828

[30] Foreign Application Priority Data Dec. 10, 1970 Germany ..P 20 60 682.0 Dec. 10, 1970 Germany...l-1GM 70 45 527.5

[52] US. Cl. ..336/60, 336/65, 336/84, 336/184, 336/212, 336/219 [51] Int. Cl ..H0lf 27/10, HOlf 15/04 [58] Field of Search ..336/60, 55, 65, 90, 92, 180, 336/184, 84, 212, 219, 234,12

7/1965 Wetherill ..336/212 X Primary Examiner-Thomas J. Kozma Attorn qeorge H. Spencer, et al.

[5 7] ABSTRACT A choke for high voltage mains. The choke includes two identical partial windings having turns wound in opposite directions to one another. The magnetic circuit includes a ferromagnetic upper yoke and a ferromagnetic lower yoke. The upper ends of the partial windings are electrically connected to the upper yoke to which is applied the full potential to be applied to the choke and the lower ends of the partial windings are electrically connected to the lower yoke. The magnetic circuit includes two magnetic core members extending between the upper yoke and the lower yoke. The partial windings are each disposed respectively about individual ones of the magnetic core members. Two insulating columns each having an upper opening and a lower opening surround respectively individual ones of the partial windings. Two shielding members are positioned respectively about individual ones of g the yoke members. The shielding members and the yoke members are effective to close off the upper and lower openings of the insulating columns from space outside of the choke.

20 Claims, 5 Drawing Figures PRTENTEDSEP I 2 I972 SHEET 1 OF 5 PATENTEBSEI' 1 2 m SNEU 3 BF 5 FIG. 3

PHENTEDSEP 12 I972 SHEU 5 0F 5 FIG. 5

CHOKE BACKGROUND OF THE INVENTION This invention relates to a choke having two identical, parallel connected, partial windings. The present invention more particularly, relates to a choke for very high voltage power mains and has two identical, parallel connected partial windings, the turns of the windings being wound in opposite directions with respect to one another, the partial windings being connected together in parallel by ferromagnetic yokes which also connect the cores of the respective partial windings and the upper yoke carrying the full potential applied to the choke.

Such chokes are designed principally for the voltage between a conductor and ground and are used to compensate for the reactive power of the line. At the same time the stability of the transmission is increased and the amplitude of surge voltages caused by switching operations in the line are reduced.

The previously known configurations of such chokes which are usually combinations of single-phase units into three-phase alternating current assemblies differ substantially in the design of their magnetic circuits. Arrangements are known which have air gaps distributed in the wound portions. Chokes without cores with and without return legs have also been constructed. The chokes designed for high power and very high voltages have in common, independent of their core design, that the magnetic circuit and the windings are accommodated in a housing containing oil. The housing, sometimes referred to as tank, is made of sheet metal, usually steel. The core member or members and the housing, in such known chokes, are at ground potential and the end of the windings at the high tension side is brought out of the housing via a bushing. The windings must be fully electrically insulated from the core member or members and the housing at the high voltage side. In multiphase systems, only at the end of the windings connected with a ground star point a graded insulation can be used.

U.S. Pat. No. 3,195,082 discloses an arrangement of windings and a magnetic circuit for a choke with an oilfilled housing. The arrangement includes two identical core portions and two also identical parallel-connected partial windings, the windings being wound in the opposite direction from one another. The upper yoke in this known arrangement carries the full potential applied to the choke. This known arrangement, however, is not satisfactory because it requires considerable expenditures for insulation as do the other known arrangements. The structural size of chokes constructed as proposed in the above-mentioned United States Patent is determined, to a large extent, by prescribed, required distances which depend on the operating voltage. Moreover, the required bushing substantially increases the cost and requires one-half of the available structural height of the choke.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a choke for high voltage mains which, compared to the known arrangements, requires much less insulation without any reduction in the operational safety.

It is another object of the present invention to provide a choke for high voltage mains which can be produced easily and has smaller dimensions than comparable known chokes.

The above-stated objects, as well as others which will become clear from the text which follows, are accomplished according to the present invention by providing a magnetic circuit which includes a ferromagnetic upper yoke and a ferro-magnetic lower yoke. Two identical partial windings having turns wound in opposite directions to one another have their upper ends electrically connected to the upper yoke and their lower ends electrically connected to the lower yoke. The magnetic circuit includes two magnetic core members extending between the upper yoke and the lower yoke. The partial windings are each disposed respectively about individual ones of the magnetic core members. Two insulating columns, each having an upper opening and a lower opening, surround respectively individual ones of the partial windings. Two shielding members are provided, each being positioned respectively over individual ones of the yoke members. The shielding members and the yoke members are effective to close off theupper and lower openings of the insulating columns from space outside the choke.

According to a more detailed advantageous embodiment of the present invention it is provided that the upper ends of the partial windings, the upper yoke and the associated shielding member are electrically connected together. The lower ends of the partial windings, the lower yoke and its associated shielding member may be similarly electrically connected together.

Both magnetic core members, in an advantageous further embodiment, are constructed of partial sections with intermediate, ferromagnetic flanges to which winding ends of partial winding sections are connected and which close the electrical as well as the magnetic circuit. The intermediate flanges are surrounded by a shielding member in the form of a ring.

The insulating columns may be porcelain supports and mechanical compression of the windings is preferably effected by porcelain straining chains.

Each magnetic core member desirably contains a core formed of a plurality of electrically insulated metal lamination packets and the partial windings are formed of disc coils. The thus produced high longitudinal capacitance of the partial windings effects a very favorable potential control along the insulating surface as well as an almost uniform voltage surge distribution to the individual gaps of the core.

The choke according to the present invention may be provided with means for liquid cooling the choke.

When the choke of the present invention is used as a reactor, ripple filter choke, in an arrangement for the transmission of direct currents, the lower yoke is placed on at least one and preferably two additional insulating columns to insulate electrically the partial windings from ground. The additional insulating columns are hollow and serve simultaneously to conduct the coolant. A possibly required compensation vessel for the coolant is provided by a recess in the shielding member associated with the upper yoke.

The choke having the construction according to the present invention is very advantageous because it permits the elimination of the entire main insulation of the winding, including the high voltage bushing as well as the metallic housing and a substantial amount of the coolant. Moreover, the reduction of the ground capacitances of the partial windings to the stray capacitance of the air, on the one hand, and the slim configuration originating from the spark gaps, on the other hand, greatly reduces the voltage surge stresses on the partial windings so that its internal insulation can also be reduced. Due to the very simple construction it is possible to divide the partial windings and their associated core members into partial sections so that even chokes with a very high total output can be transported in relatively small and lightweight partial sections. The partial sections can then be assembled at their intended location. With suitable selection of the structural lengths for the partial sections it is possible to construct module type chokes for a basic voltage and multiples thereof from the same type of element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view of a choke according to an embodiment of the present invention, the section being taken along line 11 of FIG. 2.

FIG. 2 is a side view of the choke illustrated in FIG. 1.

FIG. 3 is a longitudinal cross-sectional view of a second fully insulated embodiment of the present invention which is particularly useful as a ripple filter in high direct voltage mains.

FIGS. 4 and 5 are respectively cross-sectional and side views of a further, also fully insulated embodiment of the present invention, the section shown in FIG. 4 being taken along line 4-4 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a choke for high voltage mains, according to a first exemplary embodiment of the present invention, includes a first magnetic core member 1 and a second magnetic core member 2. A first partial winding 3 is arranged around the core member 1 and a second partial winding 4 is arranged around the core member 2. The partial windings 3 and 4 are wound in opposite directions with respect to one another.

The partial windings 3 and 4 are preferably constructed of interleaved double coils.

The core member 1 consists of a plurality of metal packets 5 formed of laminated sheets. The metal packets 5 are electrically insulated one from the next by interposed insulating members 6, the insulating members 6 being shown disproportionally large for purpose of clarity. The core member 2 similarly consists of a plurality of metal packets 7 formed of laminated sheets and electrically insulated one from the next by interposed insulating members 8, the insulating members 8 also being shown disproportionally large for purpose of clarity.

The dimensions of the partial winding 3 and the core member 1 are so selected that they may be accommodated within an insulating column 9 which is in the form of a porcelain support. The dimensions of the partial winding 4 and the core member 2 are similarly so Selected that they may be accommodated within an insulating column 10 which also is in the form of a porcelain support. Thus, the insulating

supports

9 and 10 simultaneously serve as insulation and as a housing of the choke.

As illustrated in FIG. 1, the magnetic core member 1 includes an upper partial section 11 and a lower partial section 12. The lower frontal face of the upper partial section 11 is developed with an outwardly extending ferromagnetic flange 13. The upper frontal face of the lower partial section 12 is also developed with an outwardly extending ferromagnetic flange 14.

The partial winding 3 includes an upper partial winding section 15 and a lower partial winding section 16 which have respectively substantially identical axial lengths as the upper partial section 11 and the lower partial section 12 of the core member 1 measured to the lowermost and uppermost lateral surfaces of the flanges l3 and 14, respectively. The upper partial winding section 15 has its lower end electrically connected to the flange l3 and the lower partial winding section 16 has its upper end connected to the flange 14.

The insulating column 9 includes an upper support section 17 and a lower support section 18 which are positioned on opposite sides of the flanges l3 and 14 which extend radially outwardly from the insulating column 9. The flanges 13 and 14 are surrounded by a shielding ring 19.

The flanges 13 and 14 directly contact one another and thus provide the electrical connection between the upper partial winding section 15 and the lower partial winding section 16 of the partial winding 3 as well as the magnetic circuit connection between the upper partial section 11 and the lower partial section 12 of the core member 1.

The magnetic core member 2 includes an upper partial section 20 and a lower partial section 21 The lower frontal face of the upper partial section 20 and the upper frontal face of the lower partial section 21 are developed respectively with radially, outwardly extending

flanges

22 and 23 which directly contact one another.

The partial winding 4 includes an upper partial winding section 24 having its lower end electrically connected to the flange 22 and a lower partial winding section 25 having its upper end electrically connected to the flange 23. The upper and lower partial winding

sections

24 and 25 have substantially identical axial lengths as the upper partial section 20 and the lower partial section 21 of the core member 4 measured to the lowermost and the uppermost lateral surfaces of the

flanges

22 and 23, respectively.

On opposite sides of the abutting

flanges

22 and 23 are positioned an upper support section 26 and a lower support section 27 which constitutes partial sections of the insulating column 10.

The flanges Y22 and 23 extend radially outwardly from the insulating column 10 and are surrounded by a shielding ring 28. It will be appreciated that the shielding ring 28 and the shielding ring 19 can be combined so as to be of unitary construction.

The

flanges

22 and 23 provide the electrical connection between the upper partial winding section 24 and the lower partial winding section 25 of the partial winding 4. The

flanges

22 and 23 additionally provide the magnetic circuit connection between the upper partial section 20 and the lower partial section 21 of the core member 4.

- tion.

The core members 1 and 2 rest on a lower yoke 29 which conducts the magnetic flux between the lower ends of the core members 1 and 2. The lower yoke 29 is, when used as a choke in an alternating voltage transmission system, at ground potential and thus need not be electrically insulated. The magnetic flux between the upper ends of the core members 1 and 2 is conducted by an upper yoke 30 which is electrically conductively connected with the high voltage terminal 31 of the choke.

The lower yoke 29 and the upper yoke 30 are preferably constructed of laminated sheets in a conventional manner. The

yokes

29 and 30 are provided respectively with shielding

members

32 and 33 which are positioned about them. The insulating

columns

9 and 10 are positioned between the shielding

members

32 and 33.

The upper yoke 30 and the lower yoke 29 are made of electrically conductive material and thus may serve respectively to provide electrical connections between the upper ends of the partial windings 3 and 4 and between the lower ends of the partial windings 3 and 4; it will be appreciated that the shielding

members

32 and 33 are also made of conductive material and may, therefore, provide electrical connections to the partial windings 3 and 4 via the

yokes

29 and 30, respectively.

In a preferred embodiment, the upper ends of the partial windings 3 and 4, the upper yoke 30 and the shielding member 33 are all electrically, conductively connected. In this case, the high voltage terminal 31 is simply connected directly to the shielding member 33. The lower ends of the partial windings 3 and 4, the lower yoke 29 and its associated shielding member 32 are also electrically conductively connected together.

The upper yoke 30 and the lower yoke 29 serve to seal from outside space the upper and lower ends of the core members 1 and 2. Between the cores and the winding and between the winding and the porcelain support respectively axially extended

channels

34, 35 for the coolant are provided. The lower shielding member 32 is provided with two

apertures

37 and 38 which are aligned with the

channels

34 and 35.

The

apertures

37 and 38, the

channels

34 and 35 define a channel for conducting a coolant, such as oil, through the choke structure via input and output valves (not shown in FIG. 1). It will be understood, however, that the channel for conducting coolant could also include a passageway through the lower yoke 29 and that the coolant system could be self-contained within the choke structure.

A recess 39 is provided within the shielding member 33 to serve as a compensation vessel for the coolant.

In addition to the coolant channel arrangement as shown in FIG. 1, provisions may be made for circulating oil through the partial windings 3 and 4 in a known conventional manner. Such a conventional arrangement could also be used as an alternative to the coolant channel arrangement shown in FIG. 1.

The upper yoke 30 and the lower yoke 29 serve to clamp the adjacent partial sections of the core members l and 2 together via force supplied by a plurality of tensioned insulating chains 41 (FIG. 2) which are preferably of porcelain and extend between the shielding

members

33 and 32 and are connected thereto by conventional means. The shielding

members

33 and 32 also, by reason of the force supplied by the insulating chains 41, are operative to clamp the adjacent partial winding sections of the partial windings 3 and 4.

Since the lower yoke 29 may be grounded, the choke embodiment illustrated in FIG. 1 can best be used for single-phase operation or for star-connected alternating current mains.

When the choke is to be used in high direct voltage transmission systems, the lower yoke 29 must be fully insulated as shown in the embodiment of FIG. 3. As shown in FIG. 3, two additional hollow, insulating columns 40 and 42 in the form of porcelain supports are provided below the lower yoke 29 and its associated shielding member 32.

The hollow insulating columns 40 and 42 are provided respectively with longitudinal bores 43 and 44 which are disposed in axial alignment with the

apertures

38 and 37, respectively, in the lower shielding member 32. Thus, insulating columns 40 and 42 not only support and insulate the lower yoke 29, but also serve to guide coolant, such as oil, to the aperture 37 and from the aperture 38 in the lower shielding member 32 in cooperation with an inlet valve, diagrammatically shown in the numeral 45, and an outlet valve diagrammatically shown at the numeral 46.

The remaining parts of the choke illustrated in FIG. 3 correspond to those of the choke illustrated in FIGS. 1 and 2.

Referring to FIGS. 4 and 5, a choke for high voltage, according to a further embodiment of the present invention includes a first magnetic core member 36 and a second magnetic core member 47. A first partial winding 48 and a second partial winding 49 are respectively arranged around the

core members

36 and 47. The partial windings 48 and 49 are preferably constructed of interleaved double coils.

The

core members

36 and 47 consist of a plurality of metal packets formed by laminated sheets with electrical insulating members interposed between the metal packets similarly to the arrangement of the core members shown in FIG. 1.

A hollow insulating column 50, in the form of a porcelain support, is provided, the partial winding 48 and the core member 36 being accommodated within the insulating column 50. A second insulating column 51, also in the form of a porcelain support, is arranged to accommodate the partial winding 49 and the core member 47 The

core members

36 and 47 rest on a lower yoke 52 which conducts flux between the lower end of the core member 36 and the lower end of a core member (not illustrated) which is accommodated within a third insulating column 53 shown in FIG. 5. The lower yoke 52 also conducts flux between the lower end of the core member 47 and the lower end of a core member (not illustrated) which is accommodated within an additional insulating column not visible in FIGS. 4 and 5. The ad ditional insulating column is positioned, with respect to the insulating column 51 as the insulating column 53 is positioned with respect to the insulating column 50, the additional insulating column being hidden behind the insulating column 51 of FIG. 4 and behind the insulating column 53 ofFIG. 5.

In a preferred operating arrangement the two flux paths through the lower yoke 52 are in opposite directions, the lower yoke operating in effect as a saddle area.

The upper ends of the

core members

36 and 47 are positioned respectively against an upper yoke 54 and an upper yoke 55. The upper yoke 54 provides a flux path between the upper end of the core member 36 and the core member (not illustrated) which is accommodated within the insulating column 53 (FIG. The upper yoke 55 provides a flux path between the upper end of the core member 47 and the upper end of the core member (not illustrated) which is accommodated within the additional insulating column which cannot be seen in FIGS. 4 and 5, it being hidden behind insulating column 53 shown in FIG. 5.

The lower yoke 52 and the

upper yokes

54 and 55 are preferably constructed of laminated sheets. The upper yokes 54 and 55 are provided respectively with

metallic shielding members

56 and 57, and the lower yoke 52 is provided with a metallic shielding member 58.

The upper end of the partial winding 49, the yoke 55 and the shielding member 57, as well as the upper end of the partial winding which is within the third insulating column 53 (FIG. 5) preferably are electrically, conductively connected together. The upper end of the partial winding 48, the yoke 54, the shielding member 56 and the upper end of the partial winding which is accommodatedwithin the additional insulating column not visible in FIGS. 4 and 5 are also preferably electrically, conductively connected together. Thus direct high voltage conductive connections can be made to the partial windings 48 and 49 via the shielding

members

56 and 57, respectively.

The lower ends of the partial windings 48 and 49, as well as lower ends of the other partial windings not visible in FIGS. 4 and 5, the lower yoke member 52 and the shielding member 58 are preferably electrically, conductively connected together. In this case, conductive connections to the lower ends of all the partial windings can be made via the shielding member 58.

The upper yokes 54 and 55 seal the upper ends of all core members from outside space, and the lower yoke 52 seals the lower ends of all core members from outside space.

Each of the four core members is provided with channels only core members 46 and 47 and their associated

channels

59 and 60 being visible in FIG. 4. Passageways 61 and 62 are provided respectively around the

upper yoke members

54 and 55, the passageways 61 and 62 providing fluid communication for each of the

channels

59 and 60 with their associated channels in the other core members which are not visible in FIGS. 4 and 5. A fluid passageway, generally designated by the numeral 63, is provided around the lower yoke 52 for providing fluid communication with the

axial channels

59 and 60. A second passageway,

which is not visible in FIGS. 4 and 5, is provided around the lower yoke member 52 for providing fluid communication with the axial channels around the two core members which cannot be seen in FIGS. 4 and 5.

Two additional, hollow, insulating

columns

65 and 64 in the form of porcelain supports are provided below the lower yoke 52 and the shielding member 58. Each of the insulating

columns

64 and 65 includes a longitudinally extending bore, only one bore 66 being visible in FIG. 4. The bore 66 is in fluid communication with the passageway 63. The similar bore within the insulating column 64 is in fluid communication with the second passageway within the lower yoke members 52.

The two insulating

columns

64 and 65 not only support and insulate the lower yoke 52, but also serve to guide coolant, such as oil, toward and away from the four core members, only

core members

36 and 47 being visible in FIG. 4. While neither of the

upper yokes

54 and 55, as illustrated, is provided with a recess to serve as a compensation vessel for the coolant, it is to be understood that such recesses may be provided, the recesses being constructed similarly to the recess 39 shown in FIG. 1.

Although each of the core members 46 and 47, as shown in FIG. 4, do not have flanges, it is to be appreciated that the core members may have flanges, thereby allowing the choke to be constructed in a modular fashion as shown in FIG. 1, the partial windings and insulating columns also being appropriately modified.

It is to be appreciated that for some applications, the choke shown in FIGS. 4 and 5 may be constructed without the additional insulating

columns

64 and 65.

Although the choke shown in FIGS. 4 and 5 provide for circulating coolant, such as oil, through a coolant channel extending around the core members and yokes, it is to be appreciated that provisions additionally could be made for circulating the coolant through the partial windings in a known conventional manner or such conventional arrangement could be used as an alternative to the cooling arrangement shown in FIG. 4.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim 1. A choke for high voltage mains comprising in combination: two substantially identical partial windings disposed about respective magnetic core members, said partial windings having turns wound in opposite directions to one another and each having an upper end and a lower end; a ferromagnetic upper yoke and a ferromagnetic lower yoke connecting said core members to provide a closed magnetic circuit, said upper yoke being electrically connected to said upper ends of said partial windings and said lower yoke being electrically connected to said lower ends of said partial windings; means for connecting the full potential to be carried by said choke to said upper yoke; housing means in the form of two insulating columns each having an upper opening and a lower opening, and each surrounding a respective individual one of said partial windings; and two shielding members each positioned about a respective individual one of said yoke members, said shielding members and said yoke members closing off said upper openings and said lower openings of said insulating columns from the space outside of the choke.

2. A choke as defined in claim 1 further comprising means operatively arranged within said housing for liquid cooling the choke.

3. A choke as defined in claim 1 wherein said upper ends of said partial windings, said upper yoke and its associated one of said shielding members are electrically, conductively connected together.

4. A choke as defined in claim 1 wherein said lower ends of said partial windings, said lower yoke and its associated one of said shielding members are electrically, conductively connected together.

5. A choke as defined in claim 1 wherein said partial windings are each respectively composed of partial winding sections, each partial winding section having an end defining an intermediate point of one of said partial windings; said magnetic core members are each constructed of partial core sections and each includes an outwardly extending intermediate flange, a respective one of each of said ends defining intermediate points of said partial windings being connected to a respective one of said flanges and said flanges of adjacent partial core sections being in contact for closing the electrical circuit of the choke as well as the mag netic circuit of the choke; and further comprising a shielding means positioned over at least a portion of said flanges.

6. A choke as defined in claim 3 wherein said partial windings are each respectively composed of partial winding sections, each partial winding section having an end defining an intermediate point of one of said partial windings; said magnetic core members are each constructed of partial core sections and each includes an outwardly extending intermediate flange, a respective one of each of said ends defining intermediate points of said partial windings being connected to a respective one of said flanges and said flanges of adjacent partial core sections being in contact for closing the electrical circuit of the choke as well as the magnetic circuit of the choke; and further comprising a shielding means positioned over at least a portion of said flanges.

7. A choke as defined in claim 1 wherein said insulating columns each comprise a porcelain support means.

8. A choke as defined in claim 3 wherein said insulating columns each comprise a porcelain support means.

9. A choke as defined in claim 6 wherein said insulating columns each comprise a porcelain support means.

10. A choke as defined in claim 9 further comprising insulating chain members connected between said shielding means for clamping said partial windings.

11. A choke as defined in claim 1 wherein each of said magnetic core members comprises a plurality of electrically insulated lamination packets.

12. A choke as defined in claim 11 wherein each of said partial windings comprises a plurality of disc coils.

13. A choke as defined in claim 1 further comprising at least one additional insulating column disposed beneath said lower yoke for insulating said lower yoke from reference potential whereby the choke may be used as a reactor in a transmission circuit for direct cur- 'i d. A choke as defined in claim 4 further comprising at least one additional insulating column disposed beneath said lower yoke for insulating said lower yoke from reference potential whereby the choke may be used as a reactor in a transmission circuit for direct current.

15. A choke as defined in claim 2 wherein said means for liquid cooling the choke comprises channels around said upper yoke, said lower yoke and said magnetic core members for the circulation of a liquid coolant.

16. A choke as defined in claim 13 wherein said upper yoke, said lower yoke, said magnetic core members and said at least one additional insulating column are provided with channels for circulation of a liquid coolant.

17. A choke as defined in claim 2 wherein the shielding element associated with said upper yoke contains a recess comprising a compensation vessel for liquid coolant.

18. A choke as defined in claim 1 further comprising a third and a fourth substantially identical partial winding disposed respectively about additional core members, said third and said fourth partial windings having turns wound in opposite directions to one another and each having an upper end and a lower end; a second ferromagnetic upper yoke and said ferromagnetic lower yoke connecting said additional core members in parallel to provide a closed magnetic circuit, said second upper yoke being electrically connected to said upper ends of said third and said fourth partial windings and said lower yoke being electrically connected to said lower ends of said third and said fourth partial windings; additional housing means in the form of a third and a fourth insulating column each having an upper opening and a lower opening and each surrounding a respective individual one of said third and said fourth partial windings; a third shielding member positioned about said second upper yoke, said third shielding member and said upper yoke closing off the upper openings of said third and said fourth insulating columns from space outside of the choke and said lower yoke and its associated shielding member closing off the lower openings of said third and said fourth insulating columns from space outside the choke.

19. A choke as defined in claim 18 further comprising at least one additional insulating column disposed beneath said lower yoke for insulating said lower yoke from reference potential whereby the choke may be used as a reactor in a transmission circuit for direct current.

20. A choke as defined in claim 19 wherein the lower ends of said partial windings, said lower yoke and its associated one of said shielding members are electrically, conductively connected together.

Claims

1. A choke for high voltage mains comprising in combination: two substantially identical partial windings disposed about respective magnetic core members, said partial windings having turns wound in opposite directions to one another and each having an upper end and a lower end; a ferromagnetic upper yoke and a ferromagnetic lower yoke connecting said core members to provide a closed magnetic circuit, said upper yoke being electrically connected to said upper ends of said partial windings and said lower yoke being electrically connected to said lower ends of said partial windings; means for connecting the full potential to be carried by said choke to said upper yoke; housing means in the form of two insulating columns each having an upper opening and a lower opening, and each surrounding a respective individual one of said partial windings; and two shielding members each positioned about a respective individual one of said yoke members, said shielding members and said yoke members closing off said upper openings and said lower openings of said insulating columns from the space outside of the choke.

5. A choke as defined in claim 1 wherein said partial windings are each respectively composed of partial winding sections, each partial winding section having an end defining an intermediate point of one of said partial windings; said magnetic core members are each constructed of partial core sections and each includes an outwardly extending intermediate flange, a respective one of each of said ends defining intermediate points of said partial windings being connected to a respective one of said flanges and said flanges of adjacent partial core sections being in contact for closing the electrical circuit of the choke as well as the magnetic circuit of the choke; and further comprising a shielding means positioned over at least a portion of said flanges.

13. A choke as defined in claim 1 further comprising at least one additional insulating column disposed beneath said lower yoke for insulating said lower yoke from reference potential whereby the choke may be used as a reactor in a transmission circuit for direct current.

14. A choke as defined in claim 4 further comprising at least one additional insulating column disposed beneath said lower yoke for insulating said lower yoke from reference potential whereby the choke may be used as a reactor in a transmission circuit for direct current.