GB1591597A

GB1591597A - Electrical connector

Info

Publication number: GB1591597A
Application number: GB19075/78A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1977-06-09
Filing date: 1978-05-11
Publication date: 1981-06-24
Also published as: IN148548B; DE2726402C3; FR2394197A1; DE2726402A1; IT7824212A0; DE2726402B2; TR20162A; IT1095084B; FR2394197B1; CH626755A5; SE7806367L; HU175172B

Abstract

In order to produce a connection on two single-wire, screened heavy-current cables having extruded plastic insulation and an outer conductive layer, the use of a prefabricated elastomeric insulating body (3) is proposed, which is pushed onto the insulation of the wire ends which are to be connected to one another. The insulating body (3) contains a centrally arranged, embedded control electrode (4). Control deflectors (5) consisting of elastomeric material are embedded on the inside of the cylindrically constructed ends of the insulating body, and a metallic screen (7) is fitted on the outer electrically conductive layer (6) of the insulating body. <IMAGE>

Description

(54) ELECTRICAL CONNECTOR (71) We, SIEMENS AKTIENGESELL SCHAFT, a German company, of Berlin and Munich, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to electrical connectors and is particularly although not exclusively concerned with connectors for screened heavy-current cables.

For simplifying the assembly in the production of electrical connectors in the form of joint boxes for single-core screened heavycurrent cables having plastics insulation and an external conducting layer, various constructions have become known in which prefabricated individual parts are used for the production of thejoint box, so as to avoid the production of insulating wrappings, and the welding thereof in some cases, as was previously usual. A known construction of such a joint box consists, for example, of a metal housing which is filled with an insulating oil and in which a connecting member and control electrodes are disposed with the aid of an insulating spacer. The prepared cable ends are pushed from both sides into the said housing, the conductor ends provided with contact members engaging in the connecting member, while the outer conducting layers of the cable conductors come into contact with the control elements. The cable screens are connected to the metal housing by way of a special terminal connecting element (United States Patent Specification No. 3 571 783).

In another known joint box, there is provided instead of a liquid insulating medium a soft insulating body which surrounds the connecting point of the core ends and which is subjected to axial pressure by means of spring elements (German Offenlegungsschrift No. 17 65 925). Other known joint boxes are constructed without a metallic housing. They are transversely divided, two insulating bodies being pushed axially one into the other. The two insulating bodies are in this case provided with an outer electrically semiconducting layer of plastics, which is in electrical contact with the screen of the two cable ends (German Auslegeschrift No.

14 65 493).

Other known joint constructions of this kind comprise, on the inside surface of insulating bodies, embedded inserts of weak electrical conductivity, which are in contact with a connecting member of the conductor ends by way of resilient contact elements (German Offenlegungsschriften Nos. 21 19 804, and 25 53 331). In these known connecting sleeves, an external screening is provided for the joint, but the plastics layer of weak electrical conductivity which is used for this purpose does not constitute reliable protection against electrical shock.

In a further known joint box for screened heavy-current cables, the point of connection of the conductor ends is surrounded by a single insulating body consisting of elastomeric material, which is pushed as a whole over the point of connection and bears on the insulation of the conductor ends. There is embedded in the insulating body a resilient control electrode consisting of a material having weak electrical conductivity, which is in contact with the point of connection of the conductors by way of resilient elements. An outer conducting layer of the insulating body is electrically connected to the screens of the cable ends by means of a wrapping. In this case, control electrodes are provided, which bear on the conically tapering ends of the insulating body (German Auslegeschrift No.

16 65 222).

It is also known to employ for end seals of screened heavy-current cables prefabricated insulating bodies consisting of elastomeric material in which control deflectors, also consisting of elastomeric material, are embedded and of which foot portions bear both on the outer conducting layer of the cable conductor and on the metallic screen of the cable (German Gebrauchsmuster No. 74 35 080).

According to the present invention, there is provided an electrical connector for electrically connecting together two electric cables each having an electrically conductive core, an insulation layer around the core, an outer electrically conductive layer around the insulation layer, and an electrically conductive screen around the outer electrically conductive layer, the connector comprising: a resilient electrically insulative body having cylindrical end regions and arranged to bear against said insulation layer around a stripped cable in the connector; an electrical connecting member for making electrical contact with said cores of stripped cables in the connector; a resilient screening electrode embedded in said insulative body around said connecting member and arranged to be electrically connected, use of the connector, to said connecting member or the cores of cables in contact therewith; at least one electrical stress grading element of elastomeric material embedded in said insulative body at a respective end region thereof and arranged to bear resiliently against said screen and against said outer electrically conductive layer and/or insulation layer around a stripped cable in the connector; a layer of material of weak electrical conductivity around said insulative body; and a metallic screening around said layer of material of weak electrical conductivity and arranged to be electrically connected, in use of the connector, to said screen of a stripped cable in the connector.

The said metallic screening preferably comprises a flexible tube or a strip of metallic material. In this case, it is desirable for the connector to be surrounded by an outer protective covering consisting of a shrunk-on flexible tube, which may also afford protection against corrosion. In another advantageous possibility, the said metallic screening comprises a metal housing which covers the electrical connector and which bears against the said layer of material of weak conductivity, which is then of compressible form. In this case, a good moisture-tight construction of the connector can be obtained with the aid of a solid metal housing, more particularly in the case of cables having an external metal sheathing. The compressible outer layer of material of weak electrical conductivity advantageously consists of foamed plastics, or it may alternatively be in the form of a skin of material which has, at optionally regular intervals, ribs which may extend in the peripheral direction or in the longitudinal direction and which bear against the metal housing.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, which illustrates one embodiment of the invention, and shows, in section, one half of an 'electrical line connector in the form of a joint box for two single-core heavyduty cables. The other half of the connector is substantially symmetrical with the illustrated half.

The figure shows the end of a heavycurrent cable 11, which is connected within the joint box 10 to the end of another cable (not particularly shown). The heavy-current cable consists of a central electrical conductor 12, an extruded polyethylene insulation layer 13, an extruded outer electrically conducting layer 14, a screen 15 built up of copper wires, and an external sheathing 16 consisting of polyvinyl chloride. The cable end is stripped down in a conventional stepped manner and the exposed end of the conductor 12 is connected to the conductor end of the adjacent cable by means of a connecting member in the form of a sleeve connector 1. There has previously been pushed on to the adjacent cable end, from which the sheathing and screen has been removed over an appropriate distance, an electrically insulating body 3 which, after the connection of the conductor ends, is so pushed over the point of connection that a centrally embedded resilient screening electrode 4 consisting of material having poor electrical conductivity comes into contact with the conductor 12 by way of resilient contact element 2 mounted about the point of connection. Control deflectors 5 embedded at the ends of the insulating body 3 bear against the bared outer conducting layer 14 of the cable core and the screen 15, which is bent back over on to the cable sheathing 16. The control deflectors 5 constitute electrical stress grading elements, or electrical stress relief cones, which control the electric fields where the outer conducting layers 14 are terminated. The insulating body 3 is of cylindrical form, more particularly at its ends, so that the embedded control deflectors 5 are surrounded by sufficiently resilient insulating material to be able to bear with sufficient pressure on the bared cable screen.

The insulating body 3 furthermore carries an outer conducting layer 6 of a material of weak electrical conductivity, around which a metal screening 7 in the form of a flexible tube of metal fabric has been applied. The metal screening 7 and the screen 15 of the cable are mounted on a distance angle piece 8 applied to the cable sheathing 16 and electrically conductively connected thereto and thus to one another by a clip (not particularly shown). Extending over the whole joint box 10 is a shrunk-on flexible tube 9 which, after having been shrunk on, tightly surrounds the point of connection and constitutes the outer protection for the joint box.

The internal diameter of the insulating body 3 is, in known manner, made somewhat smaller than the external diameter of the cable insulation in order that the insulating body 3 bears against the cable insulation 13 without any cavities, after having been pushed over the cable ends.

Instead of the connecting member 1 in the form of a sleeve connector, as illustrated in the figure, there may be employed to connect the conductor ends a contact member known per se, which is embedded in the screening electrode 4 and which contains resilient contact elements which bear on contact pins mounted on the conductor ends. In this case, the two correspondingly prepared cable ends are merely pushed into the insulating body 3 from both ends, the electrical connection of the conductor ends automatically being established.

Instead of the proposed metallic screening 7 consisting of a flexible tube of metal fabric and the outer protective covering 9 consisting of a shrunk-on flexible tube, there may be provided as the housing of the joint box 10 a solid metal housing, in which case the outer conducting layer 6 preferably consists of a foamed plastics on which the metal housing bears. The layer of foamed material then forms a compressible cushion for the changes of volume of the insulating body 3 which take place during assembly. The metal housing is secured about the sheaths of the cables to be connected with the aid of sealing elements known per se.

It may be appreciated that the illustrated joint box may be readily assembled from prefabricated parts. As indicated above, the control deflectors 5 embedded in the insulating body 3 are sufficiently covered by resilient insulating material, so that in the electrically highly loaded region, i.e. at the steppeddown point of the cable screen 15 and of the outer conducting layer 14 of the cable core, it is ensured that the insulating body 3 is pressed against the cable cores with sufficient force. At the same time, good protection against shock is afforded by the metallic screening 7 which is applied around the insulating body 3 and which is electrically connected to the cable screen 15.

Thus the illustrated embodiment can provide a joint box for single-core, screened heavy-current cables having an extruded plastics insulation and an outer conducting layer, which is made proof against high voltage and against shock with the use of a prefabricated elastomeric insulating body.

The reader's attention is directed to our copending application No. 19074/78, (Serial No. 1591596) which is directed to similar subject-matter.

WHAT WE CLAIM IS:- 1. An electrical connector for electrically connecting together two electric cables each having an electrically conductive core, an insulation layer around the core, an outer electrically conductive layer around the insulation layer, and an electrically conductive screen around the outer electrically conductive layer, the connector comprising: a resilient electrically insulative body having cylindrical end regions and arranged to bear against said insulation layer around a stripped cable in the connector; an electrical connecting member for making electrical contact with said cores of stripped cables in the connector; a resilient screening electrode embedded in said insulative body around said connecting member and arranged to be electrically connected, in use of the connector, to said connecting member or the cores of cables in contact therewith; at least one electrical stress grading element of elastomeric material embedded in said insulative body at a respective end region thereof, and arranged to bear resiliently against said screen and against said outer electrically conductive layer and/or insulation layer around a stripped cable in the connector; a layer of material of weak electrical conductivity around said insulative body; and a metallic screening around said layer of material of weak electrical conductivity and arranged to be electrically connected, in use of the connector, to said screen of a stripped cable in the connector.

2. A connector according to claim 1, wherein said metallic screening comprises a flexible tube or a strip of metallic material, and a flexible covering is shrunk around the screening, to cover the electrical connector.

3. A connector according to claim 1, wherein said material of weak electrical conductivity is compressible and said metallic screening comprises a metal housing which bears against said layer of material of weak conductivity and covers the electrical connector.

4. A connector according to claim 3, wherein said compressible material is a foamed plastics material.

5. A connector according to claim 3, wherein said compressible material consists of a skin of material provided with ribs which bear against said metal housing.

6. An electrical connector substantially as hereinbefore described with reference to the accompanying drawings.

7. An electrical connector according to any preceding claim, in combination with two stripped cables secured in the connector, each cable having an electrically conductive core in electrical contact with said connecting member and electrically connected either directly or via the connecting member to said screening electrode, an insulation layer around the core around which layer said

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. smaller than the external diameter of the cable insulation in order that the insulating body 3 bears against the cable insulation 13 without any cavities, after having been pushed over the cable ends. Instead of the connecting member 1 in the form of a sleeve connector, as illustrated in the figure, there may be employed to connect the conductor ends a contact member known per se, which is embedded in the screening electrode 4 and which contains resilient contact elements which bear on contact pins mounted on the conductor ends. In this case, the two correspondingly prepared cable ends are merely pushed into the insulating body 3 from both ends, the electrical connection of the conductor ends automatically being established. Instead of the proposed metallic screening 7 consisting of a flexible tube of metal fabric and the outer protective covering 9 consisting of a shrunk-on flexible tube, there may be provided as the housing of the joint box 10 a solid metal housing, in which case the outer conducting layer 6 preferably consists of a foamed plastics on which the metal housing bears. The layer of foamed material then forms a compressible cushion for the changes of volume of the insulating body 3 which take place during assembly. The metal housing is secured about the sheaths of the cables to be connected with the aid of sealing elements known per se. It may be appreciated that the illustrated joint box may be readily assembled from prefabricated parts. As indicated above, the control deflectors 5 embedded in the insulating body 3 are sufficiently covered by resilient insulating material, so that in the electrically highly loaded region, i.e. at the steppeddown point of the cable screen 15 and of the outer conducting layer 14 of the cable core, it is ensured that the insulating body 3 is pressed against the cable cores with sufficient force. At the same time, good protection against shock is afforded by the metallic screening 7 which is applied around the insulating body 3 and which is electrically connected to the cable screen 15. Thus the illustrated embodiment can provide a joint box for single-core, screened heavy-current cables having an extruded plastics insulation and an outer conducting layer, which is made proof against high voltage and against shock with the use of a prefabricated elastomeric insulating body. The reader's attention is directed to our copending application No. 19074/78, (Serial No. 1591596) which is directed to similar subject-matter. WHAT WE CLAIM IS:-

1. An electrical connector for electrically connecting together two electric cables each having an electrically conductive core, an insulation layer around the core, an outer electrically conductive layer around the insulation layer, and an electrically conductive screen around the outer electrically conductive layer, the connector comprising: a resilient electrically insulative body having cylindrical end regions and arranged to bear against said insulation layer around a stripped cable in the connector; an electrical connecting member for making electrical contact with said cores of stripped cables in the connector; a resilient screening electrode embedded in said insulative body around said connecting member and arranged to be electrically connected, in use of the connector, to said connecting member or the cores of cables in contact therewith; at least one electrical stress grading element of elastomeric material embedded in said insulative body at a respective end region thereof, and arranged to bear resiliently against said screen and against said outer electrically conductive layer and/or insulation layer around a stripped cable in the connector; a layer of material of weak electrical conductivity around said insulative body; and a metallic screening around said layer of material of weak electrical conductivity and arranged to be electrically connected, in use of the connector, to said screen of a stripped cable in the connector.

insulative body bears, an outer electrically conductive layer around the insulation layer, and an electrically conductive screen around the insulation layer, around which outer electrically conductive layer and screen a respective said electrical stress grading element bears, the screen being electrically connected to said metallic screening.

8. A combination according to claim 7, wherein each cable is a single-core heavy duty cable in which said insulation layer is of extruded plastics.