EP2287864B1 - Tubular leadthrough - Google Patents

Abstract

The lead-out tube (10) has a screen tube (12) made of an electrically conductive material. The screen tube extends in a hollow cylindrical manner around a path (14) in its axial direction. The lead-out tube comprises a hollow cylindrical electric insulating layer (16) which is arranged at a radial distance (20) around the screen tube along its axial extension. The insulating layer made of band-shaped insulating material is wound around strips (18) that are flexible in sections. The strips are arranged along the paths at another radial distance (22) around the screen tube. An independent claim is also included for a method for manufacturing a lead-out tube for high-voltage transformers.

Description

The invention relates to a discharge tube for high-voltage transformers, comprising a shield tube made of an electrically conductive material, which extends hollow cylindrical around an at least partially curved path in the axial direction and with a hollow cylindrical molded electrical insulation layer, which at a first radial distance around the shield tube along the axial extent is arranged

It is well known that high voltage transformers for power grids are arranged in a voltage level greater than or equal to 110kV for isolation reasons and for better dissipation of heat generated during operation mostly in a filled with oil transformer tank. The external electrical connections are in this case arranged in the form of corresponding outlets on the transformer tank.

For an electrical connection from the winding ends of the transformer windings in the transformer winding of the high-voltage transformer to the outlets, it is therefore necessary to guide respective electrical connection conductors through the oil-filled transformer tank. In this case, there are the difficulties that on the one hand, the connecting conductor diameter is relatively small, for example a few cm, and on the other hand, for reasons of space, a conductor guide in close proximity to adjacent components with a high electrical potential difference, for example Kernpreßteilen or another winding, is necessary. Thus, there is a high risk of unwanted breakdowns or at least partial discharges, if in regions a corresponding electric field strength is exceeded.

It is customary in accordance with the prior art to surround the respective connecting conductor along its extension with a discharge tube which limits the maximum occurring electric field strength. A discharge tube initially has an inner shielding tube made of conductive material, in the interior of which the connecting conductor is arranged. During operation of the transformer, the shielding tube is set to the same electrical potential as the conductor running in it, so that there is no potential difference between connecting conductor and shielding tube and breakdown or partial discharge within the shielding tube can not occur.

The shield tube in turn is either insulated from a thick single-layer insulating layer, or is surrounded by a plurality of hollow cylindrical arranged around this and radially adjacent barriers of an insulating material, wherein between the barriers each a space for the flow of transformer oil is provided. The latter variant with isolation barriers has clear electrical advantages over a single-layer insulation layer.

The production of such barriers with partially curved shield tubes proves to be laborious, especially since discharge pipes are to be regarded as a single production due to the very small number of production of identical power transformers. Due to an improved space utilization within the transformer tank usually even more points of curvature are provided.

According to the state of the art, either a modular component system is used for the barriers of diversion tubes, but in this case not more than one point of curvature of, for example, 90 ° is possible. Alternatively, it is also possible to make specially made half-shell parts for the barriers, which, although several bends are feasible, but a considerable manufacturing effort also means for corresponding forms for a production of the half-shell parts. Due to the above-mentioned infrequent production of identically constructed transformers, however, it is precisely the production of an individual shape that entails an undesirably high expense. At the points of overlap between adjacent modules or half-shells also results in an electrical vulnerability of the barrier.

In the patent CH 695968 A5 Disclosing the preamble of claim 1, there is disclosed a head electrode for discharging oil-insulated power transformers having an electrically conductive hollow body with a barrier-like outer insulation, the outer insulation being made of a plurality of prefabricated parts pushed onto the hollow body and overlapping one another.

Based on this prior art, it is an object of the invention to provide an improved Ausleitungsrohr for high-voltage transformers, which is particularly easy to customize. It is also an object of the invention to provide a corresponding manufacturing method.

This object is achieved by a discharge pipe according to claim 1.

The basic idea of the invention is to wind the barriers or insulation layers of a band-like insulating material-preferably with the addition of an adhesive-directly around the shield tube, which for example has a diameter of 60 mm to 150 mm. This allows easy custom fabrication of any forms of barriers and also avoids the problem of overlap locations between adjacent components of an insulating layer. A winding process of, for example, a 3 mm thick insulation layer of several layers of an insulating tape is - even if it is done manually - in the end very quickly, because any preparatory work such as the production of a mold and a subsequent manufacturing a molding advantageously omitted. In addition, but just a winding process to a pipe shape also correspondingly easy to automate.

In order to realize an oil-flooded cavity between the shield tube and the surrounding insulating layer or even a cavity between two adjacent insulating layers, however, the band-shaped insulating material can can not be wound directly onto a radially inner surface. According to the invention therefore, a winding of the band-shaped insulating material is provided around a plurality of cylindrical and preferably parallel to each other arranged strips. Along the cylinder circumference, such strips should be provided, for example, in angular steps of 15 ° to 45 °, so that ultimately no circular but a polygonal cross section of the wound insulation layer results. It has been shown that the electrical functionality of a barrier with a polygonal cross-section (> = 8-fold polygon) equals a circular cross-section of a barrier. The strips themselves are made of an electrically insulating material.

In the bending region of the shielding tube, the strips must follow its curvature since, according to the invention, they each have the same radial distance from the shielding tube along their extent. Therefore, it is provided to design the strips flexible at least in the curvature areas, so to allow flexibility in all directions. For example, if a strip is disposed over a screen tube that is curved downwardly, the strip must be bendable along its axial extent in a vertical direction. In the case of a curvature running to the left or right, a bendability in the horizontal direction must be present.

To simplify the arrangement of strips according to the invention, it is therefore advantageous, although not absolutely necessary, to use the same strip type for at least one and the same strip layer, which has a correspondingly high flexibility in the respective bending region.

It also makes sense, although not absolutely necessary, to provide flexibility of the strips only in the areas of curvature and to specify a rigidity of the strips in the remaining, straight areas. Thus, the stability of the wound insulation layer is increased in the axially straight regions.

In this way, the production of a shielding tube is a hollow cylindrical enclosing insulation layer, or a barrier, with a radially underlying Cavity for the flooding with oil in a simple manner given also for very complex Schirmrohrgeometrien with a variety of curvature areas, the aforementioned disadvantages are avoided.

In a preferred embodiment of the diversion tube a plurality of radially spaced insulation layers are provided. Thus, several isolation barriers are realized with underlying cavity for the oil to be flooded, whereby the distances to components with other electrical potentials can be reduced.

In a particularly preferred variant of the diversion tube according to the invention, the at least partially flexible strips are designed as angled profile and are provided at least in the region of curvature with a plurality of slots transversely to their respective axial extent. An angled profile, for example, with at least two arranged at an angle of 90 ° to each other and interconnected flat bars has low material consumption on the one hand a high stability in all possible bending directions, which proves to be particularly advantageous for the straight sections. On the other hand, a flexibility of the strip can be achieved in a simple manner by slitting such flat strips in a simple manner, so that ultimately a plurality of vertebral-like strip sections are pronounced, which are flexibly connected to one another via a non-slit core region of the strip.

According to a particularly preferred embodiment of the diversion tube according to the invention, the angled profile of a flexible strip is designed as an X, T, V and / or Y profile. If a bar is arranged directly on a cylindrical outer surface, for example, directly on the screen tube, then here in particular an X, an inverted Y or an inverted Y-profile offer, which then forms a particular with a respective two flat bars formed surface ensures good contact, for example, in an adhesive bond.

According to a further embodiment, the shield tube is in its radially outer region of a base insulating layer, for example, a few mm Thickness wrapped. The insulating material in question is - deviating from the above-mentioned insulating layers - preferably applied as a wet material, which after curing has a correspondingly high mechanical strength and good contact with the shield tube.

In a further preferred variant of the invention, the radially innermost insulating layer is spaced from the screen tube or from its base insulating layer directly by the strips. In a structure of the diversion tube with a plurality of barriers and a plurality of cavities arranged radially below for the passage of oil, it has proven to be expedient to increase the radial thickness of the cavities with increasing radial distance from the shield tube, ie, for example, 10 mm thickness for the radially innermost cavity , 25mm for a second and possibly 40mm for a third, if required. A thickness of about 10 mm is particularly easy to specify by a corresponding thickness of the respective strips, while thicknesses of 15 mm and higher would require strips with an inappropriately high cross-section, although this is of course also possible.

In a particularly preferred embodiment of the discharge tube according to the invention arranged at a radial distance around the shield tube bars are at least one insulating layer along its axial extent with a plurality of each axially spaced, arranged transversely to the curved path and an inner opening having support rings each at the radially outer periphery connected.

These support rings advantageously allow an increased thickness of the respective cavity - for example, 40mm - at a lower strip cross-section - for example, 15mm. The use of one and the same type of strip is then possible with several radially spaced insulation layers or barriers. These support rings are preferably to be pushed over the shield tube or over an already arranged insulation layer during production and distributed equidistantly in the axial direction, for example every 15 cm to 40 cm, wherein in the curved region a reduced distance of adjacent support rings makes sense. In this area, the respective strips according to the invention are in fact flexible and should also be supported accordingly more.

According to one embodiment of the invention, at least one support ring encloses a radially inner insulation layer with its inner opening in a mechanical operative connection. This is useful for reasons of stability.

Particularly simple is such an operative connection can be realized if the inner opening of a support ring is polygonal, with the same number of corners as the number of strips, by which the radially underlying insulating layer is supported. Namely, if the outer cross section of the insulating layer and the inner cross section of the opening of the support ring are similar, but differ in diameter, for example by a few percent, a support ring is particularly easy to push over the insulating layer. By a subsequent rotational movement of the support ring about the axial axis of this is then particularly easy to connect in a clamping connection with the insulating layer. When using support rings in several insulation layers, it is usually useful for reasons of stability to arrange them nested in one another.

In order to ensure an axially continuous polygonal outer cross section of an insulating layer and the outer circumference of a support ring is preferably polygonal design.

In a further embodiment, the cross section of at least one support ring next to the inner opening further recesses. These are in particular provided to allow a flow through the axially formed by the support rings axially adjacent cavity segments with oil.

The material of a support ring is to choose in each case electrically insulating. Pressspan has proven particularly suitable. This is both easy to work, has a high mechanical stability and is capable of being permanently immersed in oil. In an equally advantageous manner, the flexible strips of pressboard can be produced, of course, other materials may be suitable.

In a variant of the invention, the band-shaped insulating material predominantly consists of a cellulose-based material, which can be wound particularly well. A more complicated use of a hardening wet material as in the basic insulation layer is not necessary. In a further inventive embodiment of the invention, the band-shaped insulating material is coated on at least one side with an adhesive layer. Thus, a slipping of the wound insulation tape is prevented in an advantageous manner.

When using discharge pipes according to the invention in an oil transformer, the advantages according to the invention lead to an accelerated and simplified production process and possibly also to a smaller size due to the improved electrical properties.

• Anordnung von zumindest abschnittsweise flexiblen Leisten auf einer Kreisbahn um ein zumindest abschnittsweise gekrümmtes isoliertes Schirmrohr jeweils längs dessen axialer Erstreckung in einem radialen Abstand zu diesem
• bedarfsweises Biegen der Leisten entsprechend der Krümmung des Schirmrohres
• Fixierung der Leisten, beispielsweise durch eine Klebeverbindung
• Umwickeln der Leistenanordnung mit einem bandförmigen Isolationsmaterial, so dass eine das Schirmrohr umschließende und zu diesem beabstandete erste Isolationsschicht gebildet ist
• Überschieben von mehreren Stützringen über die so gebildete hohlzylindrische Isolationsschicht
• axiale Beabstandung und Fixierung der Stützringe, beispielsweise durch eine Klemmverbindung
• Anordnung von abschnittsweise flexiblen Leisten auf einer Kreisbahn um die Außenradien der Stützringe jeweils längs der axialen Erstreckung des abschnittsweise gekrümmten Schirmrohres
• bedarfsweises Biegen der Leisten entsprechend der Biegung des Schirmrohres
• Fixierung der Leisten, beispielsweise durch eine Klemmverbindung
• Umwickeln der Leistenanordnung mit einem bandförmigen Isolationsmaterial, so dass eine die erste Isolationsschicht umschließende und zu dieser beabstandete zweite Isolationsschicht gebildet ist

The object according to the invention is also achieved by a method for producing a sectionally curved discharge tube for high-voltage transformers according to claims 1 to 13, comprising at least the following steps:

• Arrangement of at least partially flexible strips on a circular path about an at least partially curved insulated shield tube along the axial extent thereof at a radial distance to this
• as required bending the strips according to the curvature of the shield tube
• Fixation of the strips, for example by an adhesive bond
• Wrapping the strip assembly with a band-shaped insulating material, so that a screen tube surrounding and spaced therefrom first insulation layer is formed
• Slipping of several support rings on the thus formed hollow cylindrical insulating layer
• axial spacing and fixation of the support rings, for example by a clamp connection
• Arrangement of sections of flexible strips on a circular path around the outer radii of the support rings in each case along the axial extent of the partially curved shield tube
• As required bending the strips according to the bending of the shield tube
• Fixation of the strips, for example by a clamp connection
• Wrapping the strip assembly with a band-shaped insulating material, so that a first insulating layer surrounding and spaced therefrom second insulation layer is formed

The advantages according to the invention correspond to those which have already been described above.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail.

• Fig. 1 ein erstes Ausleitungsrohr in einer vereinfachten Darstellung,
• Fig. 2 ein zweites Ausleitungsrohr in vereinfachter Darstellung,
• Fig. 3 ein drittes Ausleitungsrohr in vereinfachter Darstellung,
• Fig. 4 eine neunte flexible Leiste,
• Fig. 5 eine zehnte flexible Leiste,
• Fig. 6 eine elfte flexible Leiste und
• Fig. 7 einen dritten Stützring

Show it:

• Fig. 1 a first diversion tube in a simplified representation,
• Fig. 2 a second diversion tube in a simplified representation,
• Fig. 3 a third diversion tube in a simplified representation,
• Fig. 4 a ninth flexible strip,
• Fig. 5 a tenth flexible strip,
• Fig. 6 an eleventh flexible strip and
• Fig. 7 a third support ring

Fig. 1 shows a first discharge pipe in a simplified sectional view 10. To a first shield tube 12, which is made for example of aluminum and has an outer diameter of 120mm, a wound first insulating layer 16 is arranged with a polygonal cross section. Both the first shielding tube 12 and the first insulating layer 16 are arranged in a hollow cylindrical manner around a curved path 14, which in this illustration should be regarded as emerging from the illustrated plane.

At a radial distance 22 to the surface of the screen tube 12 along a path 14 imaginary circular path 24 a plurality of first flexible strips 18 are arranged with a T-shaped cross-section. The crossbar of the T-profile is particularly suitable to be wrapped by a band-shaped insulating material. There is a sharp edge avoided, which could damage the wound tape. The concrete attachment of the strips 18 and the arrangement of other components in the space between the shield tube 12 and circular path 24 are left undecided in this illustration and will be described below. The strips 18 are arranged in this cross-sectional representation equidistant star-shaped around the path 14, so that an approximately circular polygonal cross-section results, which results from the strips supported wound insulation layer The insulating layer 16 has, for example, a thickness of a few mm, which results from a multi-layered and axially offset winding with the band-shaped insulating material. The cross-sectional segments between the circular path 24 and the inner circumference of the insulating layer 16 each represent a cavities, which are flooded with a later installation of the discharge pipe in a transformer of oil.

Fig. 2 shows a second discharge pipe in a simplified plan view 30, partially in a sectional view. To a partially straight and partially curved in the area 46 path 34, which essentially describes the course of a second discharge pipe surrounded, not shown connecting conductor, a second tube 32 is arranged in a hollow cylindrical, which in particular also follows the curvature of the path 34. This is conductive and placed in the installed state in the transformer to the same electrical potential as the inside - not shown - conductor. Thus, the electric field strength is reduced by the conductor set at voltage potential.

A third flexible strip 38 is connected in the upper region of the screen tube and along the curved path with the surface of the screen tube 32, for example by an adhesive connection. Within a curved region 46, the third strip 38 is provided with slots, which ensure flexibility in this area. Thus, it is possible that it follows the right bend of the screen tube 32. A second 36 and a fourth 40 ledge are on the two side faces of the Umbrella tube 32 indicated, which are also slotted in the curved area and follow the respective bending direction.

There are more flexible strips around the outer periphery of the screen tube 32 to be assumed, but these are not shown in this illustration for illustrative reasons. All these strips together form an inner strip arrangement on which an inner insulating layer 49 is wound from strip-shaped insulating material. For reasons of drawing, this insulating layer 49 extends in the illustration only over part of the axial length of the screen tube 32 and is also shown deviating in a sectional view. However, it is assumed to be along the entire axial length and completely wound around the circumference of the screen tube 32.

Arranged around this inner insulation layer 49 are a plurality of support rings 50 in an axially predominantly equidistant spacing, the inner opening circumference of which forms a mechanical operative connection with the outer circumference of the inner insulation layer 49. Such an operative connection can be advantageously achieved by an axial rotational movement of a support ring 50 relative to the enclosed inner insulation layer 49, provided that both have a matched polygonal cross-section with an intermediate gap.

Analogous to the inner strip arrangement further strips, which are indicated by the reference numerals 42 and 44, are now arranged along the curved path 34 at a greater radial distance. These are supported by the support rings 50 and form an outer strip assembly. Analogous to the inner insulation layer around the inner strip arrangement, a second insulation layer 48 is wound around the outer strip arrangement, which, of course, also extends along the entire screen tube 32 in a departure from the illustration.

Fig. 3 shows a third discharge pipe in a simplified sectional view. In this example, a base insulating layer 64 made of a wet material, which has already hardened, is first attached to a third screen tube 62. This prevents direct contact with the conductive screen tube 62. Along its circular circumference are equidistant and parallel to each other several flexible Led strip 66 having an X-shaped cross-section, which space a radially overlying third insulating layer 70. The X profiles are formed wider and contiguous in their radially inner region so as to be able to establish good mechanical contact with the base insulation layer 64 of the shielding tube 62 on the one hand and also to simplify the mechanical positioning of the strips 50. In the radially outer region adjacent to the third insulating layer 70, the X-profile also proves to be favorable, because thus also a larger bearing surface for the third insulating layer 70 is given. The space thus spaced is intended to be flooded with transformer oil.

A second polygonal support ring 72 made of pressboard encloses with its inner circumferential cross section the polygonal third insulating layer 70 formed. Its inner periphery is provided with a plurality of second recesses 76, which initially ensure a flow-through with oil. Furthermore, these recesses 76 but give the support ring 72 and its polygonal internal structure. This is important to clamp the support ring 72 on the third insulating layer 70, wherein in this illustration the clamped state is shown. A rotation of the ring by about 18 ° to the left or right would solve this clamp connection and the ring is then particularly easy to move over the third insulating layer 70.

Correspondingly, first recesses 74 are also provided along the outer circumference of the support ring 72, which likewise ensure an axial permeability of the support ring with transformer oil. The peripheral areas, which are not recessed, are covered by a respective transverse bar of a respective T-shaped bar 68, which is clamped with its longitudinal bar in a corresponding slot on the outer circumference of the support ring 72. By the first recesses 74 it is ensured that the wound around the strips 68 fourth insulating layer 78 is supported only by the strips and therefore also has along its entire axial extent a polygonal cross-section.

Fig. 4 shows a ninth flexible strip with T-profile in a three-dimensional view 80 and in a cross-sectional view 81. The flexible, slotted region is indicated along the arrow 82 and the slots with the reference numeral 84. The cross section such a bar is for example 20mm x 15mm, with a slot being 2mm wide, for example. In the cross-sectional drawing 81, the slotted areas 88 and the core area 86 are shown.

Fig. 5 shows a tenth flexible strip with V-profile in a three-dimensional view 100 and in a cross-sectional view 101. The flexible, slotted area is indicated along the arrow 102 and the slots with the reference numeral 104. In the cross-sectional drawing 101, the slit areas 106 and Core area 108 shown. According to shows Fig. 6 an eleventh X-profile flexible strip in a three-dimensional view 120 and in a cross-sectional view 121. The flexible slotted region is indicated along the arrow 122 and the staggered slots are designated by the reference numeral 124.

Fig. 7 shows the support ring 72 from the Fig. 3 in a three-dimensional detail representation 130.

LIST OF REFERENCE NUMBERS

10

first diversion tube in a simplified representation

12

first screen tube

14

curved path

16

first insulation layer

18

first flexible strips

20

first radial distance

22

second radial distance

24

orbit

30

second diversion tube in a simplified representation

32

second screen tube

34

curved path

36

second flexible bar

38

third flexible bar

40

fourth flexible bar

42

fifth flexible bar

44

sixth flexible bar

46

curved area

48

second insulation layer

49

inner insulation layer

50

first support rings

60

third diversion tube in a simplified representation

62

third screen tube

64

Basic insulation layer

66

seventh flexible strips

68

Eighth flexible strips

70

third insulation layer

72

second support ring

74

first recess

76

second recess

78

fourth insulation layer

80

ninth flexible bar

81

Cross-sectional profile of the ninth flexible strip

82

Curvature of the ninth flexible strip

84

slots

86

Core section area of the ninth flexible strip

88

Slot area of the ninth flexible strip

100

tenth flexible strip

101

Cross-sectional profile of the tenth flexible strip

102

Curve area of the tenth flexible strip

104

slots

106

Slot area of the tenth flexible ledge

108

Core section area of the tenth flexible strip

120

eleventh flexible strip

121

Cross-sectional profile of the eleventh flexible strip

122

Curvature of the eleventh flexible strip

124

slots

130

third support ring

Claims (15)

1. Lead-out tube (10, 30, 60) for high-voltage transformers, with a shielding tube (12, 32, 62) consisting of an electrically conductive material which extends hollow-cylindrically around an at least sectionally curved path (14, 34) in the axial direction thereof, with a hollow-cylindrical, shaped electrical insulting layer (16, 48, 49, 70, 78), which is arranged at a first radial distance (20) around the shielding tube (12, 32, 62) along the axial extent thereof, wherein strips (18, 36, 33, 40, 42, 44, 66, 68, 80, 100, 120) are each arranged adjacent to one another at a second radial distance around the shielding tube (12, 32, 62), characterized in that said strips are each arranged along the at least sectionally curved path (14, 34) and are at least sectionally flexible, and in that the insulating layer (16, 48, 49, 70, 78) is wound from a tape-like insulting material around the strips (18, 36, 38, 40, 42, 44, 66, 68, 8C, 100, 120).
2. Lead-out tube according to Claim 1, characterized in that a plurality of radially spaced-apart insulating layers (48, 49, 70, 78) are provided.
3. Lead-out tube according to either of Claims 1 and 2, characterized in that the at least sectionally flexible strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) are configured, as an angled profile and are provided, at least in the region of curvature (46), with a plurality of slots (84, 104, 124) transversely with respect to the respective axial extent thereof.
4. Lead-out tube according to Claim 3, characterized in that the angled profile of a flexible strip (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) is in the form of an X-shaped (121), T-shaped (81), V-shaped (101) and/or Y-shaped profile.
5. Lead-out tube according to one of the receding claims, characterized in that the shielding tube (12, 32, 62) is enveloped in its radially outer region by a basic insulating layer (64).
6. Lead-out tube according to one of the preceding claims, characterised in that the radially innermost insulating layer (70) is spaced apart from the shieling tube (12, 32, 62) or from the basic insulating layer (64) thereof directly by the strips (66).
7. Lead-out tube according to one of the preceding claims, characterized in that the strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120), which are arranged at a radical distance (22) around the shielding tube (12, 32, 62), of at least one insulating layer (16, 48, 70, 78) are connected, along their axial extent, to a plurality of supporting rings (50, 72, 130), in each case on the radially outer circumference thereof, said supporting rings each being spaced apart axially from one another, being arranged transversely with respect to the curved path (14, 34) and having an inner opening.
8. Lead-out tube according to Claim 7, characterized in that at least one supporting ring (50, 72, 130) surrounds a radially inner insulating layer (70) with its inner opening with a mechanically operative connection.
9. Lead-out tube according to either of Claims 7 and 8, characterized in that the inner opening of the supporting ring (50, 72, 130) and/or the radially outer circumference thereof are polygonal.
10. Lead-out tube according to one of Claims 7 to 9, characterized in that the cross section of at least one supporting ring (50, 72, 130) has further cutouts (74, 76), in addition to the inner opening.
11. Lead-out tube according to one of Claims 7 to 10, characterized in that the supporting ring (50, 72, 130) consists at least predominantly of pressboard.
12. Lead-out tube according to one of the preceding claims, characterized in that the tape-like insulting material consists predominantly of a cellulose-based material.
13. Lead-out tube according to one of the preceding claims, characterized in that the tape-like insulating material is coated on at least one side with an adhesive layer.
14. Oil-filled transformer witch at least one lead-out tube according to one of Claims 1 to 13.
15. Method for producing a sectionally curved lead-out tube (10, 30, 60) for high-voltage transformers corresponding to Claims 1 to 13, comprising at least the following steps:

    • arranging at least sectionally (82, 102, 122) flexible strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) on a circular path (24) around an at least sectionally curved insulated shielding tube (12, 32, 62) in each case along the axial extent thereof at a radial distance (22) therefrom

    • bending, if necessary, the strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) corresponding to the curvature (46) of the shielding tube (12, 32, 62)

    • fixing the strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120)

    • winding a tape-like insulating material around the strip arrangement, with the result that a first insulating layer (70) is formed which surrounds the shielding tube (12, 32, 62) and is spaced apart (20) therefrom

    • pushing a plurality of supporting rings (50, 72, 130) over the hollow-cylindrical insulating layer (16, 48, 49, 70, 78) formed in this way

    • axially spacing-apart and fixing the supporting rings (50, 72, 130)

    • arranging sectionally flexible strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) on a circular path (24) around the outer radii of the supporting rings (50, 72, 130) in each case along the axial extent of the sectionally curved shielding tube (12, 32, 62)

    • bending, if necessary, the strips (18, 36, 38, 40, 42, 44, 66, 68, 80, 100, 120) corresponding to the bend (46) of the shielding tube (12, 32, 62)

    • fixing the strips

    • winding a tape-like insulating material around the strip arrangement, with the result that a second insulating layer (78) is formed which surrounds the first insulating layer and is spaced apart therefrom.

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