TECHNICAL FIELD

The invention described here relates to a termination of a cable for high- tension alternating current and insulated with a solid polymer material. The termination is primarily intended for cable with an operating voltage of 12 kV or 24 kV.

BACKGROUND ART

Cable terminations with termination details of synthetic rubber of the ethene- propene-diene rubber (EPDM) type are known, and an example of one is described in the Swedish patent SE-C-7611450-3.

DISCLOSURE OF THE INVENTION

In the inventive termination there are included at least two beaker-shaped caps of surface-leakage-proof insulation material, which are pushed over the end of the cable divested of exterior insulation, with the cable passing through the bottom of the cap, with the bottom part of the cap first put in place surrounded by the opening of the second cap and so on, each cap enclosing a separate, gas- filled space. The opening of the cap fitted first is closed by a disc insulatingly surrounding the cable.

The separate gas- filled room in each cap is filled with an insulating gas, which may be to advantage sulphur hexafluoride, SF,.

The arrangement with gas-filled spaces in the cable termination affords the advantage over previously known cable terminations that the weight of the termination is reduced, since a previously used solid insulation material has been replaced by a gaseous insulation. Furthermore, the termination with retained low weight has an outside diameter so large that the electrical field strength in all the incorporated parts is low and the risk of surface leakage current is small.

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When the cable termination is to be installed outdoors, caps are used which are formed about their openings with a collar increasing surface creeping distance.

Where the cable outer sheath has its boundary, the cable is surrounded by a field control device, known per se, and this is surrounded by one of the caps, preferably the one pushed on first.

BRIEF DESCRIPTION OF DRAWINGS

An embodiment of a cable termination in accordance with the invention will now be described, with reference to the accompanying drawing, which illustrates a longitudinal section through the termination, its caps and their collars for increasing the surface-leakage path.

BEST MODE FOR CARRYING OUT THE INVENTION

As will be seen from the drawing, in the embodiment of a cable termination in accordance with the invention a cable 1 for high-tension AC current and insulated with solid polymer material is stripped at its end and provided with a cable lug 2. For a distance 3 nearest the lug the cable is divested of its outer sheath and its conductive screening layer so that only the solid polymer material insulation remains. The boundary for the exterior insulation of the cable is surrounded by a field control device 4, known per se, for smoothing out electrical field strength acting on the insulation in the longitudinal direction of the cable.

The end of the cable is surrounded by a plurality of beaker-shaped caps 5 of surface-leakage-proof insulation material, which in this case is EPDM rubber. The caps 5 are mounted on the cable with their bottoms facing towards the end of it, holes in the bottoms of the caps surrounding the cable with a tight fit. The bottom part of the cap 5A fitted first is surrounded by the opening of the second cap 5B; the second cap being fitted over the first one to about a third of its length. The first-fitted cap 5A surrounds the field control device 4.

The first-fitted cap 5A has its open end closed by an insulating disc 6, which is placed on the cable beforehand.

Gas-tight spaces 7 are arranged in each of the caps 5, by placing the caps insid each other and with the aid of the disc 6. The closed spaces are filled wit insulating gas, sulphur hexafluoride SF, in this case.

To advantage, when the termination is to be installed outdoors, caps are use with it which are formed with a radially extending, substantially flat rai guard 8, known per se.

The following claims are intended to be applicable to terminations wit alternative embodiment. For example, the number of caps 5 shall be dependen on the operating voltage of the cable, i.e. the embodiment with two cap illustrated here being intended for a voltage of 12 kV, 4 caps for 24 kV an 6 caps for 36 kV. The length of the termination increases with about 100 m for each additional cap.

In the described embodiment the caps 5 are made from synthetic EPDM rubber but may also be made from other similar material, e.g. silicone rubber.

In order that the termination can be used with cables of different dimension the caps are intended to be made in several sizes, one size of the caps bein used for cables with considerably varying dimensions so that the number o sizes of the caps is only moderate.

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