DE102005054641A1 - Cable end connection for high voltage cables has support function and field control unit and fluid-free internal space - Google Patents

Abstract

A cable end connection for high voltage cables comprises a screen insulator (9), a head armature (7) through which a connecting bolt (6) conductively passes and a base armature (2) through which a cable (1) end, comprising a cable strand and insulator, passes and is sealed. The free end of the cable strand is connected to the connection bolt and there is a field control body (4) and a screened plastic insulator (5) on the cable strand.

Description

The The invention relates to a cable termination with a support function, especially for electric high voltage cable. The cable termination consists of an insulator body with shielding, a head fitting, through which a connecting bolt sealing introduced is, and a foot valve, through which a cable end is passed sealingly. Such cable terminations are as well as the interior as well as for suitable for outdoor use.

Cable terminations are used for connecting a cable to another high-voltage component, for example, with an overhead line or a high voltage busbar. The insulator body should at the same time a supporter function fulfill, namely take over lateral and axial forces. It is made of porcelain or, more recently, of one Composite material, usually a GRP pipe and a shielding made of a silicone material.

Cable terminations, the made of several individual components and materials with different thermal expansion coefficients must exist, so must be engineered to be fully functional at all temperatures remains secured. The terminations can therefore, among other things, do not consist purely of high-strength material, because they are the thermal expansion the insulated cable core would not allow. The thermal expansion in the cable end closure is therefore made of deformable materials or elements (liquids, Gases, springs or elastic plastic parts).

The electrical strength within the insulator body would be at a bare laying the cable end is not guaranteed. It is therefore known, the interior of the insulator body with an insulating liquid, for example poly-isobutene, to fill. The insulating fluid allows a higher one internal rollover resistance and prevents too conductive bridges premier Precipitation on the inside of the insulating tube with changeable climatic conditions. The operation of cable terminations should however over stay maintenance-free for many years. It can therefore after a certain Operating time to first Leaving unnoticed leaks come through the part of the insulating fluid can be lost, so that the internal withstand voltage then is no longer guaranteed. In a repair would be Furthermore a shutdown of the relevant system and extensive installation work required.

Other solutions have been proposed so that the problem of insulating loss does not occur. That's how it is DE 199 48 439 A1 known to provide a crosslinkable liquid insulating material for the interior filling, which later assumes a gel-like or foam-like consistency. However, the solution has not been able to prevail in practice, since it can not be predicted with sufficient certainty whether it can be ensured over the service life of a cable termination that the plastic permanently adheres to the cable core on the one hand and to the inner wall of the insulator body on the other hand. The individual parts of the cable end closure are in fact exposed to high temperature cycles, which can lead to a detachment of the insulating agent and thus create internal creepage paths.

A possible solution was therefore sought in the construction of "dry" cable terminations form cable terminations, which consist of a pushed onto the cable end elastic body.

Should Such cable terminations supporters properties get, have to however, relief efforts be taken because the elastic silicone body alone no mechanical Take over forces can. It is known to the silicone insulator body To provide both ends with a fitting and these fittings with at least three insulator support bodies too then concentrically surrounding the silicone insulator body.

Is known by DE 199 45 148 A1 also the use of a solid insulator mass, for example a paper roll impregnated with epoxy resin. A pressure element ensures a firm contact pressure between the paper reel and a cable plug attached to the cable end, so that a permanent seal is ensured and the thermal expansion is compensated.

disadvantage the last two solutions is the high cost, the unacceptable cost compared to one liquid-filled cable termination leads.

Of the Invention is based on the object of specifying a cable termination, which has a "dry" interior, however, it can be finished with acceptable effort.

According to the invention Task solved by the features of claim 1. Advantageous embodiments are the subject the dependent claims.

After that are on the cable core a field control body and a plastic existing, shielded insulator body mounted.

The plastic insulator body consists in be vorzugter way of superimposed, glued together individual screen bodies.

Of the Plastic insulator body can also be glued on the cable core, rotationally symmetric, in a cross-section zig-zag, bellows-like on top of each other joined Single shield parts be constructed. In addition, here in the direction the cable core directed portions of the single-screen parts respectively by a cylindrical Supported pressing element become.

When Material for the plastic insulator body comes in particular silicone rubber in question, besides EPDM or others Elastomers.

In more preferred according to the invention Way is the plastic insulator body so in the outer insulator body of Cable termination used that a contact pressure of the umbrellas on the inner surface of the insulator body is exercised. In a particularly preferred manner, it is used so that the umbrellas the plastic insulator body looking outside arch up. Any accumulating condensation will then remain on the lowest point of the umbrellas and can not cohesive wetting form.

Possibly can, for example, over the foot valve, an access to the interior of the cable termination be provided over the an air exchange possible is, so that after a certain period of operation a drying of the possibly dampened interior is made possible.

The Invention will be explained below with reference to two embodiments. In the associated Drawings show:

1 FIG. 2: a cross section through a cable end closure according to the invention, FIG.

2 : the area of the cable core isolated according to the invention in an enlarged view,

3 a cross section through a second variant of a cable end closure according to the invention in two modifications and

4 : the area of the cable core insulated according to the invention 3 in an enlarged view.

In 1 the cable end closure according to the invention is shown in a cross-sectional view. A cable 1 is through a foot valve 2 of the cable termination introduced into this. At the end of the cable the cable insulation is removed. The thus free cable core 3 is first with a field control 4 Mistake. The field control 4 consists of a field control body made of an elastomer with conductive inner moldings as control electrodes. Above the field control 4 is a plastic insulator body 5 on the cable core 3 raised with stretch. The end of the cable core 3 that over the plastic insulator body 5 protrudes, is with a connecting bolt 6 pressed or welded. The connecting bolt 6 is through a head fitting 7 with seal 8th led to the outside.

base fitting 2 and head fitting 7 are through an outer insulator body 9 connected. The insulator body 9 exists, like 2 in an enlarged view shows, from an inner fiberglass tube 10 and a silicone shield 11 ,

The plastic insulator body 5 consists of glued individual screens 12 made of silicone rubber.

The field control 4 and the one from the individual screens 12 constructed plastic insulator body 5 alone are already able to reduce the field strength even in a gas environment so that even under increased stress, no partial discharges occur. The support function is, however, by the outer insulator body 9 Fulfills.

The plastic insulator body 5 is with its individual screens 12 so in the GRP pipe 10 pushed in that the individual screens 12 with a certain contact pressure, the inner surface of the GRP pipe 10 touch. The arrangement of the individual screens 12 thus divides the possible Überschlagweg on isolated partial paths, which thus have an electrical strength that is much higher than for the practice and the tests is required.

The room layout inside the insulator body 9 done so in that individual, through the individual screens 12 Separate rooms creates a volume / surface ratio that causes the moisture dissolved in the volume of these individual chambers in the gas with decreasing temperatures at the critical surfaces no coherent moisture film. In other words: Under the operating temperatures (-50 ° C to + 70 ° C) and humidity values (0 to 100% relative humidity), the amount of moisture in the enclosed air can vary with the materials selected and the room layout (volume / area) selected. do not lead to dangerous creepage currents or partial discharges due to formation of precipitates on the critical surfaces.

Even under extreme conditions and extreme stresses that exceed the prescribed test requirements, locally occurring disturbances, such as ionization, can occur in the insulator body 9 do not spread and the overall strength not significantly lower. They remain localized by the room layout.

In addition, the plastic insulator body 5 as possible in the GRP pipe 10 of the outer insulator body 9 pushed in that the individual screens 12 bent at its outer edge upwards. This is achieved by using a Monatagehilfe in the form of a film tube, prior to insertion into the outer insulator body 9 over the plastic insulator body 5 is pulled and then together with the plastic insulator body 5 in the GRP pipe 10 inserted and then pulled upwards, with the edge of the individual screens 12 erects. Moisture, which may then be present in the resulting subspaces, will be in the deepest part of the then trough-shaped individual screens 12 collect and can not lead to a cohesive surface wetting.

3 shows a second variant of the plastic insulator body 5 , In this case, the plastic insulator body 5 from bellows-shaped composite single-shade parts 13 built up. The single screen parts 13 are rotationally symmetrical with respect to the axis of rotation obliquely extending disc-shaped sections and inside and outside in mutually opposite direction facing cylinder sections. The inner cylinder sections are so on the cable core 3 glued that a total of a bellows-type plastic insulator body 5 arises. The single screen parts 13 are expediently made of silicone rubber. For reinforcement, like the right side in 4 shows, inner and outer contact rings 14 be provided, which may also consist of silicone rubber.

1

electric wire

2

base fitting

3

cable wire

4

field control

5

Plastic insulator body

6

connecting bolt

7

top fitting

8th

poetry

9

insulator body

10

GRP pipe

11

Silicone rubber sheds

12

Single screens

13

Single screen parts

14

Anpressringe

Claims (10)

Cable termination with support function, in particular for high voltage cables, consisting of an insulator body ( 9 ) with shielding, a head fitting ( 7 ), through which a connecting bolt ( 6 ) is introduced conductively, and a foot fitting ( 2 ), through which the end of a cable ( 1 ), consisting of a cable core ( 3 ) and a cable insulation, sealingly passed, wherein the exposed cable core ( 3 ) of the cable ( 1 ) with the connecting bolt ( 6 ), characterized in that on the cable core ( 3 ) a field control body ( 4 ) and a shielded plastic insulator body ( 5 ) are attached. Cable end closure according to claim 1, characterized in that the plastic insulator body ( 5 ) of superimposed, glued together individual screen bodies ( 12 ) is constructed. Cable end closure according to claim 1, characterized in that the plastic insulator body ( 5 ) out on the cable core ( 3 ) glued rotationally symmetrical, in cross-section zigzag shaped, bellows-shaped superimposed single shield parts ( 13 ) is constructed. Cable termination according to claim 3, characterized in that in the direction of the cable core ( 3 ) directed portions of the single-panel parts ( 13 ) each by a cylindrical contact pressure element ( 14 ) are supported. Cable termination according to one of the preceding claims, characterized in that the insulator body ( 5 ) is made of silicone rubber. Cable termination according to one of claims 1 to 4, characterized in that the insulator body ( 5 ) is made of EPDM. Cable end closure according to one of the preceding claims, characterized in that the with the plastic insulator body ( 5 ) provided cable end in the outer insulator body ( 9 ) is inserted, that the screens of the plastic insulator body ( 5 ) a contact pressure on the inner surface of the insulator body ( 9 ) exercise. Cable termination according to claim 7, characterized in that the with the plastic insulator body ( 5 ) provided cable end in the outer insulator body ( 9 ) is inserted, that the screens of the plastic insulator body ( 5 ) bulge outwards. Cable end closure according to one of the preceding claims, characterized in that the outer insulator body ( 9 ) is a composite insulator consisting of a GRP tube ( 10 ) and a silicone shield ( 11 ). Cable termination after one of the before going claims, characterized in that the insulator body ( 9 ) is provided with access to its interior.