EP2442321A1 - Feedthrough for high voltage discharge lines in oil transformers - Google Patents

Abstract

The calotte (10) has hollow-cylindrical electrically conductive elements (12, 14) arranged around a rotational axis (20). Isolation barriers (30, 34, 38) are adapted to a form of the hollow-cylindrical element, and include flanged socket supports (30, 32) for feedthrough of a shielding pipe (26) to connection devices. The isolation barriers are spaced by isolation rings (42, 44, 46) that are arranged around the rotational axis, where the rings exhibit a wave form flattened in a radial direction.

Description

The invention relates to a cap for a high-voltage discharge, with a hollow cylindrical arranged around a rotation axis electrically conductive element which merges at its first axial end in a hemispherical shape, having a through-opening connecting device for electrical and mechanical connection of the element with an electric shield tube, with at least two spaced apart, each adapted to the shape of the hollow cylindrical element isolation barriers, which envelop this in a respective first and second spacing, wherein the isolation barriers each having a pipe neck for performing a shield tube to the connecting device.

It is well known that high-voltage transformers or high-voltage chokes, for example, with a rated voltage of 220kV or 380kV on the upper side and> 100MVA nominal power, are usually located in an oil-filled transformer tank for insulation and cooling purposes. An important function in such a transformer has the so-called transformer bushing through which the high voltage potential is brought from the air side to the winding in the transformer tank. In the case of pure air insulation, the distance from components lying at high voltage potential to the earthed transformer tank - depending on the voltage level - would have to be up to 4 m or more. By means of oil-soaked paper or pulp, which is a much higher Field stress as air withstand, the distance can be considerably reduced. If the high-voltage connection is led concentrically through a round opening into the boiler, a distance between the inner conductor and the tank of, for example, 20 cm is sufficient.

It is also known to the person skilled in the art that so-called calottes are used for this purpose in the region of the discharges. These are rotationally symmetrical hollow bodies of a metal, which have at one axial end a hemispherical conclusion with a mostly angled pipe socket for a conductor connection or a conductor bushing and at its other axial end a tapered diameter. For improved insulation, these electrically conductive hollow bodies are surrounded by a preferably double-walled barrier system made of an insulating material, which is likewise arranged inside the oil-filled transformer tank.

In the patent CH 695 968 A5 Such a dome is described. However, this has the disadvantage that the isolation barriers are very cumbersome to manufacture and, moreover, due to production due to an improvement in some places insulation capability.

Thus, for example, the spacing of the isolation barriers by means of insulating rings, in which spacer blocks are latched. On the one hand, this is cumbersome to produce as well as not optimal in terms of isolation, because selectively sharp-edged components are used within an electrically gradient-insensitive region to be electrically insulated. The use of spacer blocks proves to be disadvantageous, in particular in the hemispherical areas of the barriers, because here there is a particularly high risk that the insulation barrier to be separated rests only on corner points of the spacer blocks.

As equally disadvantageous proves the electrical connectivity of the dome with a necessary shielding tube. High-voltage discharges are mostly custom-made products, which are subject both to their own manufacturing tolerances and also subject to installation in an oil transformer whose manufacturing tolerances. A compensation of such tolerances is either by a mechanical particularly flexible connection between the shield tube and dome possible, which is undesirable for reasons of stability, or it must be applied permanently higher forces on the dome to fix the components in the desired position, which is also undesirable

Based on this prior art, it is an object of the invention to provide an easy-to-manufacture calotte with improved insulation capacity for discharges from oil-filled high-voltage transformers or other oil-insulated high voltage components, which avoids the disadvantages mentioned.

This object is achieved by a dome for a high-voltage discharge of the type mentioned. This is characterized in that the first of the second isolation barrier is spaced by at least one arranged around the axis of rotation isolation ring having a pronounced in the radial direction, preferably flattened waveform.

On the one hand, this offers manufacturing advantages because the elasticity of the insulating ring is achieved by the wave shape. The inner diameter of the elastic insulating ring is adapted to the outer diameter of the first insulation barrier, which is subject to certain fluctuations due to production. By applying a slight force along the axis of rotation, it is therefore possible to push such an insulating ring over the cylindrical region of the first isolation barrier. If the insulation ring has reached the desired position after the sliding process, it clamps there because of its elasticity and further fixing, for example, with an adhesive eliminated in an advantageous manner or is reduced to a few points. Of course, these elasticity-related advantages also become apparent when the second insulation barrier is pushed over the insulation rings clamped on the first insulation barrier. A typical diameter of such an insulating ring is, for example, 30 cm to 40 cm, wherein, if necessary, any such 10 to 25 cm axial length, such an insulating ring can be provided. The radial thickness of such an isolation ring can be a few centimeters.

In addition, there are also insulation advantages. On the one hand, the wavy shape of the insulation ring avoids sharp-edged areas. On the other hand, there is no continuous purely radially extending spacing of the isolation barriers, but the radial, ie the shortest, insulating path always has a share through the material of the insulation ring, such as pressboard, and a share by oil, with the interior of the dome in the operating state is filled, which has a positive effect on the insulation capacity. In a continuous extending in the radial direction spacing only by solid insulation material, the electric field is displaced by the higher permittivity of the same in the adjacent, electrically not so solid oil routes, which are thus electrically charged higher. In addition, the waveform increases the creepage distance and thus also increases the isolation capability of the overall arrangement.

The insulation gap extending purely through the material of the insulation ring always has a tangential transverse component and is therefore longer than the purely radial component. Due to the flattened waveform, which in each case follows the circular structure of the ring, in addition to the flattening a punctual mechanical contact between the insulating ring and each adjacent isolation barrier is avoided but rather replaced by a flat contact. Due to the flattening of the waveform, the number of radially inward wave troughs and radially outlying wave crests, in particular the number of cross connections between them, is reduced. The insulating ability between the first and second barrier is advantageously increased by all the above-mentioned aspects.

In a particularly preferred embodiment of the calotte according to the invention, the insulating ring in the region of the hemispherical shape of the conductive element is adapted radially inward and radially outward to the respective enveloping hemispherical shape of the respective adjacent isolation barriers. Thus, it is ensured in an advantageous manner that a flattened wave crest or a flattened wave trough are also mechanically contacted in the region of the hemispherical shape of the adjacent isolation barriers by the respective spherically adjusted flattened surfaces with the isolation barriers and punctiform contacting is avoided. The positioning of the isolation ring in the hemisphere area also proves to be very easy and flexible, because a ring shape in a hemispherical shape of appropriate diameter can be made at any number of angles, so that any positioning tolerances have no negative impact.

According to a variant of the invention, the conductive element is tapered at its second axial end in the form of a hemisphere section. The insulation barriers surrounding this area at a respective distance accordingly likewise have a hemispherical section-like shape, and the insulation rings with the spherically spherical, flattened wave crests or troughs can also be used there in an advantageous manner.

According to a further embodiment variant of the calotte according to the invention, the first insulation barrier is spaced from the electrically conductive element by at least partially flexible insulation strips. These can be designed according to a further embodiment as an angled profile and be provided at least in the flexible portion with a plurality of slots transverse to their respective axial extent.

This results in both manufacturing technology and insulation advantages. For example, a flexible strip, for example, having a width in a range of 2 cm to 4 cm and a thickness in a range of 1 cm to 2 cm, made of milled pressboard, for example, can be easily attached as a component along the axial length of the conductive element. Along its circumference are in preferably equidistant distance of for example 60 ° to install several such strips. Usually, however, these strips are not mounted directly on the conductive element, but this is still covered by a layer of insulation material on which the strips are then to be glued, for example.

Of course, the strips are also Stückelbar and to arrange at different angles. The arrangement of the strips in approximately parallel to the axis of rotation but especially in combination with the above and transverse to be arranged isolation rings has the advantage that the mechanical connection behavior between the insulating strip and insulation ring along the axis of rotation at least in the cylindrical Area of the dome is constant. The design as a slotted strip results on the one hand a high stability in the radial direction and on the other hand still a flexibility, which is needed for example in the hemisphere shape. The sharp-edged areas created by the slots are not detrimental to the insulation capacity insofar as they are arranged next to one another at a small distance of a few millimeters and so nevertheless homogeneity results in the distribution of the electric field.

In a particularly preferred manner, the angled profile of a flexible strip is designed as an X, V and / or Y profile. On the one hand, this brings about the mechanical advantage that such a profile can be placed particularly simply and stably on the conductive element at a cross-sectional end with two support points or support lines. Ideally, the cross-sectional shape of the strips in their at the radially inner and outer mechanical contact areas or bearing surfaces also follows the circle radius of the conductive element or the insulation barrier. On the other hand, the effect again occurs here that no purely radial spacing is achieved by the insulating material, but here too a tangential component is present, which improves the insulation capacity in the oil-filled space between the conductive element and the first insulation barrier in the operating state and the radial displacement of the electric field is minimized in the adjacent oil lines.

According to a further variant of the invention, the pipe socket neck of the first and / or second insulation barrier is formed directly on this, so that a seam is avoided. The isolation barriers are usually made with a corresponding metal mold around which, for example, a layer of wet and therefore flexible pulp or pressboard is placed. This is cured together with the metal mold in an oven. The pipe socket is usually arranged angled to the axis of rotation in the hemisphere shape, for example at an angle of 0 ° to 30 °, so that it is then necessary to design the mold for the insulation barrier such that a first mold part with cylindrical and hemispherical shape separable is executed by a second mold part with pipe neck. A separation of the two mold parts is namely necessary to the metal mold after hardening of the isolation barrier material again from the so To be able to remove newly produced molding. Due to the direct molding of the pipe socket neck, the insulation capacity of the insulation barrier is advantageously improved, because an adhesion of a pipe neck according to the cited prior art is avoided and the wall of the insulation barrier is then homogeneous. In the presence of hemispherical or tapered areas at both axial ends of the conductive element or of the surrounding isolation barriers, these production-related conditions are preferably to be made of two half-shell-like modules, which are then connected together at one axial end.

The object is also achieved by a previously described cap, which according to the invention comprises a connecting device with a first part for connecting the same with a screen tube and a second connected to the conductive element part, wherein a frictionally adjustable connection between the first and second part is provided. This allows an adjustment of the position of the dome on a screen tube, through which an electrical conductor is guided by a transformer located in the oil-filled boiler to a discharge point on the boiler wall. Thus, in particular tolerances in the arrangement of a screen tube but also manufacturing tolerances of an oil boiler or the calotte itself can be corrected to a certain extent. This circumference is essentially determined by the angular adjustability of the connecting device and is a few °, for example +/- 3 °. The connecting device is to be designed such that a guided through the passage opening conductor is always shielded to the outside, for example by suitable shielding plates, which, if necessary, when adjusting against each other are movable.

In a particularly preferred embodiment of the calotte, the non-positively adjustable connection comprises two groups of three mutually offset triangles arranged in parallel aligned screw, wherein the first group is provided to apply a tensile force between the two parts and second group for a compressive force between the two parts.

An area in the space is always defined by three points, whereby by the first group of screw connections by their respective length a surface is defined in spatial relation to the first part of the connection device, the first part being in turn intended to be connected to a screen tube , The second group of screw connections defines by their respective length a surface in spatial relation to the second part of the connection device, the second part in turn being connected to the conductive element. Characterized in that a group of screw is intended to exert a tensile force and the other group to exert a compressive force, the two parts of the connecting device can be well adjusted to each other and fix. Thus, in an adjustment process, for example, first the screw, which are provided for exerting a compressive force, be adjusted in the particular desired length. Subsequently, then fixation in the desired position by tightening the provided for applying a tensile screw.

Since only exactly three screw connections are provided, each plane is precisely determined by its length, so that a potentially bistable state, as might occur, for example, with four or five screw connections per group, is advantageously avoided. For example, in a threaded connection designed for tensile force, a screw or threaded rod extends through a non-threaded through hole of the first part of the connecting device into a thread in the second part. Correspondingly, in the case of a screw connection designed for pressing force, a screw extends through a matching continuous thread in the first part of the connecting device and then strikes the surface of the second part of the connecting device without a thread or the like being provided there. For the operation of such a connection device, it is irrelevant whether pressure or tensile force connections are arranged in the first or second part or whether it is actually a screw or other length-adjustable component. Of course, instead of a threadless through hole, through which a threaded screw is inserted and a through hole with thread conceivable through which a screw is inserted, which is in a desired Area has no thread. It is essential here that the connection in a certain area without rotational movement along the screw is displaced.

Preferably, the screw connections of at least one of the groups are arranged at equidistant spacing along a common circular path around the passage opening of the connection device. This offers geometric advantages, since the through-hole then represents a fictitious tilting point of the two connecting device parts to each other and this represents exactly the desired tipping point for a conductor connection of a transformer usually carried out there.

In a particularly preferred manner, all screw connections of the two groups are accessible through the preferably tapered second axial end of the conductive element. In a later installation of the dome in an oil transformer the screw with their screw heads are then accessible through the openings provided for the discharge openings in the transformer tank, whereas accessibility from the opposite side is not given.

According to a special embodiment of the dome, the second part of the connecting device is milled and welded into the conductive element. This allows in a simple manner a modular system, which can be generated with a few basic components or basic shapes a variety of different variants.

According to a specific embodiment of the invention, a torus-like milled electrode with drop-like cross-section widening towards the axial end is welded to the tapering second axial end of the conductive element. On the one hand, this also opens up the advantage of a modular system, on the other hand, contrary to the cited prior art, an improved electrical behavior is achieved because the decisive for a maximum field strength second axial end portion of the dome now has no sharp edges of a bending process. Preferably, the drop shape is designed such that within the dome no cavities are formed in which could accumulate when filling the respective transformer tank with oil bubbles, which could impair the isolation ability. This depends on the arrangement of the calotte within the transformer tank, which is usually approximately vertical. A suitable drop shape is characterized for example by an angle of about 20 ° to 40 ° of the lower edge of the drop shape to a plane perpendicular to the axis of rotation, which thus allows an inclination of the dome in a range slightly below 20 ° to 40 °.

In a preferred variant of the invention, the conductive element, at least part of the connecting device and / or the electrode are made of aluminum. Aluminum offers a number of advantages, such as low weight, ease of processing, good resistance and conductivity.

According to the invention it is provided in an embodiment of the dome, that the connecting device is connected in the region of the hemispherical first end of the conductive element with this and that a screen tube through the through hole of the connecting device and through an adjoining in the wall of the conductive element opening in the interior thereof is feasible. This allows a good shielding of an electrical conductor through the shield tube to directly into the interior of the electrically conductive element, in which case can be done without affecting the shield an adjustment of the connecting device. However, embodiments are also conceivable in which the parts of the connection device overlap in such a way and fulfill an umbrella function that guidance of a screen tube through the connection device is not necessary.

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

einen Schnitt durch eine erste exemplarische Kalotte,

Fig. 2

einen exemplarischen Isolationsring für den Bereich einer Halbkugelform,

Fig. 3

ein exemplarisches zweites leitfähiges Element mit Isolationsleisten,

Fig. 4

eine flexible Leiste in verschiedenen Ansichten sowie

Fig. 5

eine Verbindungsvorrichtung in Drauf- und Schnittansicht.

Show it:

Fig. 1

a section through a first exemplary dome,

Fig. 2

an exemplary isolation ring for the area of a hemisphere shape,

Fig. 3

an exemplary second conductive element with insulating strips,

Fig. 4

a flexible bar in different views as well

Fig. 5

a connecting device in plan and sectional view.

Fig. 1 shows a section through a first exemplary dome 10. About a rotational axis 20 is arranged rotationally symmetrical, a cylindrical portion 12 of a conductive element of a sheet-like material, for example, with a wall thickness of 0.8mm and a diameter of 40cm. The axial ends of the cylindrical portion 12 are indicated by the reference numerals 16 and 18. At the first axial end 16, a hemispherical portion 14 of the same sheet-like material joins, in which case cylindrical 12 and hemispherical 14 area were made together from a metal sheet and have no seam. The hemispherical region 14 of the conductive element is provided in an axially outermost region with a circular opening, in which a second part 24 of an approximately rotationally symmetrical adjustable connecting device is welded. Usually, the connecting device is aligned on the hemispherical region 14 at an angle of 0 ° to 30 ° to the rotation axis 20, in the Fig. Is shown the Sondefall of 0 °.

The second part 24 of the adjustable connecting device has, like the first 22 axially adjacent part on a disc-like hollow cylindrical shape of several millimeters thickness. To the first part 22 of the connecting device, a shield tube 26 is mounted by means of a screw clamp connection, which carries the entire weight of the dome. Through a passage opening in the connecting device, namely through the hollow cylindrical inner region of the first 22 and second 24 part, a high voltage conductor 28 is guided in the electrically shielded interior of the calotte. In order to ensure a secure shielding of the high-voltage conductor 28 for each adjustment position of the dome by screw connections indicated in FIG. 1 which connect the first 22 and second 24 parts of the connection device in a variable manner, the shield tube 26 is or electrical equivalent preferably also led into the interior of the dome.

The conductive element 12 + 14 is at a distance, for example 1 cm to 2 cm, surrounded by a first insulating barrier 30 + 34 + 38, which consists essentially of a thin, for example 1 mm to 3 mm thick and hardened layer of insulation material made of pulp. Such isolation barriers are usually produced in a special process as molded parts. The first isolation barrier 30 + 34 + 38 follows the outer contour of the conductive element 12 + 14 and therefore also has a cylindrical 38 and hemispherical 34 area. It is also provided in the region of the connecting element 22 + 24, a radially aligned pipe socket piece 30 of the first insulation barrier to build around the shield tube 26 around an insulation barrier. The spacing between the conductive element and the first insulation barrier takes place with flexible insulation strips not shown in this figure.

Around the first isolation barrier 30 + 34 + 38, a shape-like second isolation barrier 32 + 36 + 40 is arranged at a further distance, which correspondingly again has a hollow-cylindrical 40 and hemispherical 36 area with tube extension connection 32. The first 30 + 34 + 38 isolation barrier is spaced from the second 32 + 36 + 40 by means of isolation rings 42, 44, 46 of pressboard whose radially inner and outer shape in the cylindrical region 38, 40 at the respective radii and in the hemispherical region 34, 36 is adapted to the respective sphere spheres, so as to allow an optimal surface mechanical contact with the adjacent isolation barriers. A waviness of the insulation rings 42, 44, 46, which is assumed to be present, is not indicated in the FIGURE.

Fig. 2 shows an exemplary isolation ring 50 with spherically adapted outer shape. This is arranged approximately rotationally symmetrical about an axis of rotation 52, which extends in the installed state approximately together with the first axis of rotation of the calotte. But it may also be quite advantageous to provide the rotation axis 52 slightly oblique to the first axis of rotation, for example, proportional to an oblique orientation of a Rohransatzstutzens, which usually in an angular range between 0 ° and 30 ° to the first axis of rotation lies. In order to achieve an improved insulation capability between the first and second insulation barrier, a ripple of the insulation ring is provided, which is characterized by different radii 54, 56 of the insulation ring. Since oil as mentioned above has a lower permittivity than, for example, pressboard, from which such insulation rings are preferably made, it makes sense to provide a minimum waviness with respect to the thickness of the corrugated insulation material, ie, for example, a thickness of 1 cm and a ripple of + / -0.5cm or +/- 1cm. An increased ripple would further reduce the displacement of the electric field in the adjacent oil channels, but reaches at least at Pressspan to mechanical limits.

Fig. 3 FIG. 12 shows an exemplary second conductive element with insulating strips in a combined side / sectional view 60. A conductive element 62 + 64 + 66 + 68 is rotationally symmetric about an axis of rotation 70 and has a cylindrical 62 and an axially adjacent hemispherical portion 64. At the second axial end of the cylindrical portion 62, it merges into a tapered hemisphere section 66 which is welded at its outermost axial second end to a torus-like electrode having a drop-like cross-section 68. At the outermost first axial end of the conductive element, a two-part electrical and mechanical connection device 74, 76 is provided, which is connected with its first part 74 with a shield tube 72. Arranged along the axis of rotation 70 on the radially outer surface of the conductive element are a plurality of flexible strips 78, 80, 82, 84, which partially have a rigid 80 or also flexible 78, 82, 84 regions. In the latter, these are indicated by corresponding slots. Radially between the outer surface of the conductive element 62 + 64 + 66 + 68 and the flexible strips, an additional insulating layer may be provided.

Fig. 4 shows a flexible X-bar 90 in different views 92, 98. A flexible area 94 is shown enlarged in a detail drawing, in which slots 96 are shown. It can clearly be seen in the cross-sectional illustration 98 that the respective bearing surfaces follow a radius which corresponds to that of cylindrical components to be spaced apart in each case.

Fig. 5 shows a third connection device in a top 100a and a tilted in 90 ° thereto sectional view 100b. The connecting device has a disk-like, hollow-cylindrical first part 104, which is intended to be electrically and mechanically connected to a screen tube. Axially adjacent a second part 102 of similar shape is arranged, which is intended to be connected to a conductive element, for example by means of a welded joint in its hemispherical region. A first group of three parallel and perpendicular to the two disc-like parts of the connecting device aligned screw 106, 108 is disposed at the vertices of an imaginary equilateral first triangle 112 on top of the second disc-like part 102. A second group of three parallel aligned screw 110 is disposed at the vertices of a second imaginary equilateral triangle, wherein all screw connections are arranged at equidistant intervals along a respective common, in this case identical, circle. The circle encloses the hollow cylindrical interior of the two parts 102, 104 of the connecting device.

The screw connections 106, 108 of the first group are designed to exert a compressive force between the two adjacent parts 102, 104 of the connection device, as indicated by an arrow and the symbol F (= Force). Respective screws are guided through a through threaded hole of the second part 102 and spaced this with a minimum distance, depending on the rotational position of the respective screw in the thread. The screw connections 110 of the second group are designed to exert a tensile force between the two parts 102, 104 and space them with a maximum distance. In this case, a respective screw is guided through a threadless through hole of the second part 102 and opens into a thread adapted thereto in the first part 104. Both types of screw connections 106, 108, 110 are thus freely movable in one direction of movement and limiting in the opposite direction. The connecting device is locked exactly when the respective screwing apply a respective opposite locking force.

LIST OF REFERENCE NUMBERS

10

Cut through a first exemplary dome

12

cylindrical portion of first conductive element

14

hemispherical region of first conductive element

16

first axial end of the cylindrical portion

18

second axial end of the cylindrical portion

20

axis of rotation

22

first part of the first connection device

24

second part of the first connection device

26

screen tube

28

High voltage conductor

30

Pipe neck of first insulation barrier

32

Pipe neck of second insulation barrier

34

hemispherical area of first isolation barrier

36

hemispherical area of second isolation barrier

38

cylindrical area of first isolation barrier

40

cylindrical area of second isolation barrier

42

first insulation ring between the first and second insulation barrier

44

second insulation ring between the first and second insulation barrier

46

third isolation ring between first and second isolation barrier

50

exemplary isolation ring for range of hemispherical shape

52

axis of rotation

54

Inner radius in the area of a shaft tip

56

Inner radius in the area of a shaft depression

60

exemplary second conductive element with insulating strips

62

cylindrical portion of second conductive element

64

hemispherical area of second conductive element

66

hemisphere portion-shaped region of second conductive element

68

Toroidal-like electrode with a tropic-like cross-section

70

axis of rotation

72

screen tube

74

first part of second connection device

76

second part of second connection device

78

flexible range from first flexible bar

80

rigid area of first flexible bar

82

first flexible area of second flexible bar

84

second flexible area of second flexible bar

90

third flexible bar in different views

92

third flexible bar in three-dimensional view

94

flexible area of third flexible bar

96

Detail view of slots in third flexible bar

98

X-shaped cross-sectional profile of third flexible strip

100a, b

third connecting device in plan (100a) and sectional view (1 OOb)

102

second part of third connection device

104

first part of third connection device

106

first screw connection

108

second screw connection

110

third screw connection

112

first triangle

114

second triangle

116

Through opening

Claims (15)

Calotte (10) for a Hochspannungsausleitung, with a hollow cylindrical about an axis of rotation (20, 70) arranged electrically conductive element ((12 + 14), (62 + 64 + 66)), which at its first axial end (16) in a Hemispherical shape (14, 64) merges with a through opening (116) having connecting device ((22 + 24), (74 + 76), 100a, b) for electrical and mechanical connection of the element ((12 + 14), (62 + 64 + 66)) with an electric screen tube (26, 72), with at least two spaced apart, each adapted to the shape of the hollow cylindrical element ((12 + 14), (62 + 64 + 66)) isolation barriers ((30+ 34 + 38), (32 + 36 + 40)), which envelop it in a respective first and second distance, wherein the isolation barriers ((30 + 34 + 38), (32 + 36 + 40)) each have a tube attachment piece (30 , 32) for the passage of a screen tube (26, 72) to the connecting device ((22 + 24), (74 + 76), 100a, b), characterized
that the first (30 + 34 + 38) arranged on the second (32 + 36 + 40) isolation barrier through at least one about the rotation axis (20, 70) isolation ring (42, 44, 46, 50) is spaced having a radially Direction pronounced (54, 56) preferably flattened waveform. Dome according to claim 1, characterized in that the insulating ring (42, 50) in the region of the hemispherical shape (14, 64) of the conductive element ((12 + 14), (62 + 64 + 66)) radially inwardly and radially outwardly to the respective enveloping hemispherical shape (34, 36) is adapted to the respective adjacent isolation barriers. A dome according to claim 2, characterized in that the conductive element ((12 + 14), (62 + 64 + 66)) is tapered at its second axial end (18) in the form of a hemisphere portion (68). Dome according to one of the preceding claims, characterized in that the first insulation barrier (30 + 34 + 38) of the electrically conductive element ((12 + 14), (62 + 64 + 66)) by at least partially flexible insulating strips (78, 80, 82, 84, 90) is spaced apart. A dome according to claim 4, characterized in that the at least partially flexible strips (78, 80, 82, 84, 90) designed as an angled profile and provided at least in the flexible portion (94) with a plurality of slots (96) transversely to their respective axial extent are. A dome according to claim 5, characterized in that the angled profile of a flexible strip is designed as X (90), V and / or Y profile. Dome according to one of the preceding claims, characterized in that the pipe socket (30, 32) of the first and / or second insulation barrier is formed directly on this, so that a seam is avoided. A dome according to claim 2 to 7, characterized in that the connecting device comprises a first part (22, 74, 104) for connection to a shield tube (26, 72) and a second (24, 76, 102) to the conductive element ((12 + 14), (62 + 64 + 66)) and that a frictionally adjustable connection (106, 108, 110) is provided between the first (22, 74, 104) and the second (24, 76, 102) part. A dome according to claim 8, characterized in that the frictionally adjustable connection two groups of three each in mutually offset triangles (112, 114) arranged parallel aligned screw (106, 108, 110), wherein the first group (110) provided therefor is to apply a tensile force between the two parts and second group (106, 108) for applying a compressive force between the two parts. A dome according to claim 9, characterized in that the screw connections of at least one of the groups are arranged at equidistant spacing along a common circular path around the passage opening (116) of the connecting device ((22 + 24), (74 + 76), 100a, b)) , A dome according to one of claims 9 or 10, characterized in that all screw connections (106, 108, 110) of the two groups are defined by the second axial end (66) of the conductive element ((12 + 14), (62 + 64 + 66) ) are accessible. A dome according to any one of claims 8 to 11, characterized in that the second part (24, 76, 102) of the connecting device ((22 + 24), (74 + 76), 100a, b) is milled and inserted into the conductive element (( 12 + 14), (62 + 64 + 66)) is welded. Dome according to one of the preceding claims, characterized in that at the tapering second axial end (66) of the conductive element ((12 + 14), (62 + 64 + 66)) a torus-like milled electrode (68) with drop-like, to axial end welded to aufweitendem cross-section. A dome according to any one of the preceding claims, characterized in that the conductive element ((12 + 14), (62 + 64 + 66)), at least part of the connecting device ((22 + 24), (74 + 76), 100a, b) and / or the electrode (68) is made of aluminum. Dome according to one of the preceding claims, characterized in that the connecting device ((22 + 24), (74 + 76), 100a, b) in the region of the hemispherical first end (14, 64) of the conductive element is connected thereto and that a shield tube (26, 72) through the through opening (116) of the connecting device ((22 + 24), (74 + 76), 100a, b) and through an opening in the wall of the conductive element (14, 64) whose interior is feasible.

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