Casing

Abstract

A bushing for a gas-insulated switchgear comprises an electrical conductor having a longitudinal axis and embedded in an insulating material, and a coating electrode coaxially arranged at a distance from the conductor and formed from a plurality of segments.

Description

Technical Field

[0001] The invention relates to a bushing for liquid-insulated, gas-insulated or solid-insulated switchgear, in particular for medium-voltage technology, wherein the bushing comprises an electrical conductor having a longitudinal axis and embedded in the insulating material of the coated conductor, and a coated electrode, which is arranged coaxially with the conductor and spaced apart from the conductor and has a first end and a second end, the coated electrode being provided with at least one electrical terminal. Background Art

[0002] Such bushings are generally known in the prior art and serve to guide electrical conductors out of a gas-filled space in an insulated manner.

[0003] Figure 1 Such a known bushing 10 is shown, which has an electrical conductor 12 with a longitudinal axis X, wherein the conductor 12 is embedded in an insulating material 14 coating the conductor. A coating electrode 16, coaxial with and spaced apart from the conductor 12, is also embedded in the insulating material and has a first end 18 and a second end 20, neither of which protrudes from the insulating material. In the illustrated prior art, the coating electrode 16 is configured as a hollow cylinder embedded in the insulating material and is provided with two electrical terminals 22 and 24 extending from the insulating material 14 for potential control, for example, by connection to ground potential.

[0004] Current measurement typically involves inserting a toroidal transformer into such a bushing, but this increases costs. Alternatively, coated electrodes can be used directly to measure current or voltage. However, this presents a problem: as the length of the coated electrode increases, its capacitance increases. However, regulations set the maximum permissible capacitance and current, making it impossible to measure physical quantities using coated electrodes beyond a certain length. Summary of the Invention

[0005] The object of the present invention is to further develop a cannula such that a physical variable can be measured directly with the aid of coated electrodes at low production costs.

[0006] This object is achieved by the solution of the invention, in particular the coating electrode has at least two interruptions extending in the axial direction, i.e. in the direction of the longitudinal axis, from the first end to the second end, thereby forming at least two sections which are electrically insulated from each other and each provided with at least one electrical terminal.

[0007] Using the solution according to the present invention, the desired field control can still be achieved. However, the capacitance of the two segments of the coated electrode is reduced depending on the number of segments. For example, if there are two segments, the capacitance of each segment is halved compared to a coated electrode of the same length without interruptions. This allows measuring devices for different physical quantities, such as voltage, temperature, or partial discharges, to be connected to the electrical terminals of the electrically isolated segments.

[0008] The bushing according to the invention—in particular compared to bushings with metallization applied to the outside of the insulating material—can be produced very cheaply and can be used in many ways due to the increased possibilities for connecting electrical measuring devices.

[0009] Advantageous embodiments of the invention are described in the description and the drawings.

[0010] According to a first advantageous embodiment, the two segments can be formed as half shells, thereby resulting in a symmetrical design and a connection of at least two different measuring devices.

[0011] Furthermore, it is advantageous if the at least one interruption extends along a straight line, which reduces the production costs and enables a uniform potential distribution.

[0012] However, the interruption does not have to extend symmetrically or in a straight line. On the contrary, it is also advantageous if at least one interruption extends in a curved manner or spirally. In the area of the interruption, the two segments are always embedded in the insulating material and insulated from each other by the insulating material. However, it may be advantageous if at least two segments overlap along the interruption (insulated by the insulating material). Similarly, it may be advantageous to curl the two segments along the interruption. It is also advantageous if the two segments abut in a blunt manner (but are spaced apart).

[0013] In order to achieve a particularly uniform ratio, it can be advantageous if the jacket surfaces of all segments are of the same size.

[0014] On the other hand, it can also be advantageous if the individual segments have different dimensions, i.e., different jacket surfaces, since this allows for different capacitances. Thus, for example, a segment extending over 240° and a second segment extending over approximately 120° can be provided. Alternatively, a segmentation can also be implemented, wherein one segment extending over 180° and two further segments each extending over 90° can be provided.

[0015] According to a further advantageous embodiment, the segments, apart from the electrical terminals, are embedded in the insulating material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will now be described, by way of example only, with reference to advantageous embodiments and the accompanying drawings, in which:

[0017] Figure 1 is a cross section of a casing according to the prior art;

[0018] Figures 2 to 4 are different embodiments of coated electrodes;

[0019] Figure 5 a) to c) are different embodiments of two segments in the region of the interruption;

[0020] Figure 6 is through Figure 2 a cross-section of the coated electrode sleeve; and

[0021] Figure 7 is through Figure 4 Cross-section of the coated electrode casing. DETAILED DESCRIPTION

[0022] Figure 2 A first embodiment of a coating electrode 30 is shown having a first end 18 and a second end 20, wherein the coating electrode has two continuous interruptions 32 and 34 between the first end 18 and the second end 20, whereby, in this embodiment shown, the coating electrode is, as it were, divided in the longitudinal direction X, thus forming two sections A and B which are completely embedded in the insulating material, are electrically insulated from one another by the insulating material and each have an electrical terminal 22 and 24. Figure 2 In the embodiment shown, the two segments A and B are each formed as a half-shell, each half-shell having the shape of a hollow cylindrical half-cylinder. Accordingly, the two interruptions 32 and 34 extend symmetrically and in a straight line, with the spacing between the two segments in the region of the interruptions being the same in each case.

[0023] Figure 3 Another embodiment of a coating electrode 40 is shown, in which a total of three sections A, B and C are provided, with interruptions 32, 34 and 36 extending between each section, wherein all interruptions extend in the longitudinal direction X from the first end 18 to the second end 20 of the coating electrode 40. In this embodiment, three sections are thus provided with three interruptions, wherein the maintenance of the interruptions is ensured by embedding the sections in an insulating material.

[0024] Figure 4 Another embodiment of a coating electrode 50 is shown having two sections A and B formed by two interruptions 32 ′ and 34 ′, which extend in a meandering and approximately spiral manner. Here, too, each section A and B is provided with an electrical terminal 22 and 24 , respectively.

[0025] Figure 5 Different possibilities of how the segments can be formed in the area of the interruption are shown. For example, Figure 5 In a), a butt joint of two sections A and B is shown, e.g. Figure 2 、 3 Alternatively, the adjacent sections A and B may also be rolled outward or arched outward in the interruption area, as shown in FIG. Figure 5 b). Alternatively or additionally, for example according to Figure 5 For the embodiment of c), an overlapping design of the two sections A and B is conceivable.

[0026] The coating electrode or segment can be produced in a generally known manner from a wire mesh and can be bent or arched outward in the region of the first end 18 and / or the second end 20 .

[0027] Alternatively, the coating electrode can be designed as a flexible circuit board, for example a plastic film, wherein the different sections are applied as a planar surface or as a surface provided with interruptions on an insulating carrier material.

[0028] Alternatively, the sections of the coated electrodes can also be formed from a conductive or semiconductive plastic, for example by adding graphite.

[0029] Figure 6 Shows the passage with Figure 2 The longitudinal section of the sleeve 11 of the coated electrode 30, wherein the sleeve is Figure 2 The sleeve 11 has a conductor 12 with a longitudinal axis X, wherein the conductor 12 is embedded in an insulating material 14 covering the conductor. Figure 2 The coating electrode 30 is also embedded in the insulating material and has a first end 18 and a second end 20, neither of which protrudes from the insulating material. The coating electrode 30 is provided with two electrical terminals 22 and 24 extending from the insulating material 14, so that different physical quantities can be measured, for example, by connecting each terminal to a measuring device. This is possible because sections A and B of the coating electrode 30 are embedded in the insulating material and are electrically isolated.

[0030] Figure 7 Shown by having Figure 4 A longitudinal section of another sleeve 13 of the coated electrode 30, wherein the sleeve is Figure 4 The sleeve 13 has a conductor 12 with a longitudinal axis X, wherein the conductor 12 is embedded in an insulating material 14 coating the conductor. Figure 4The coating electrode 30 is also embedded in the insulating material and has a first end 18 and a second end 20, wherein the two ends do not protrude from the insulating material. The coating electrode 50 has two electrical terminals 22 and 24, which are located at the bottom of the insulating material. Figure 7 The electrodes 50 are not visible in the insulating material and are led out of the insulating material 14 so that, for example, different physical quantities can be measured by connecting each to a measuring device. This is possible because the sections A and B of the coating electrode 50 are embedded in the insulating material and are electrically isolated. Figure 7 As shown, the coating electrode 50 is provided with two interruptions 32 ′ and 34 ′.

[0031] The coated electrode according to the invention can extend in the axial direction, for example, over a length corresponding at least to the diameter of the conductor 12. The axial length of the coated electrode can in particular be two, three, six or seven times the diameter of the conductor.

Claims

1. A bushing for a switchgear, comprising: an electrical conductor (12) having a longitudinal axis (X) and embedded in an insulating material (14) coating the conductor (12); and a coating electrode, arranged coaxially and spaced apart from the conductor (12) and having a first end (18) and a second end (20), said coating electrode also being embedded in the insulating material and provided with at least one electrical terminal, The coating electrode has at least two interruptions extending in the axial direction from a first end (18) to a second end (20), thereby forming at least two sections which are electrically insulated from each other and each provided with at least one electrical terminal.

2. The sleeve according to claim 1, characterized in that The two sections are formed as half shells.

3. The sleeve according to claim 1, wherein At least one interruption extends in a straight line.

4. A bushing according to any one of the preceding claims, characterized in that The coated electrode is configured as a flexible printed circuit board, wherein the sections are arranged as conductor paths on an insulating carrier material.

5. The bushing according to any one of the preceding claims 1 to 3, characterized in that The segments are formed from conductive plastic or semiconductive plastic.

6. The sleeve according to any one of claims 1 to 3, characterized in that At least one interruption extends in a curved manner.

7. The sleeve according to any one of claims 1 to 3, characterized in that At least two sections overlap along the interruption.

8. The sleeve according to any one of claims 1 to 3, characterized in that At least two adjacent sections are provided with outwardly curved flange portions along the interruption.

9. The sleeve according to any one of claims 1 to 3, characterized in that The segment extends in the axial direction over a length corresponding at least to the diameter of the conductor (12).

10. The sleeve according to any one of claims 1 to 3, characterized in that The jacket surfaces of the two sections differ in size.

11. The sleeve according to any one of claims 1 to 3, characterized in that A measuring device for measuring a different physical quantity is connected to each terminal.

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