GB2336950A - Electrical connectors - Google Patents

Abstract

An electric connector comprises a ferrule (which is preferably longitudinally divided, in a way well-known per se, to allow it to be applied to a conductor without having access to either of its ends). The ferrule has: a middle section for compression to make connection with an insulated conductor, with or without first stripping the insulation from it; two end sections with bores capable of fluid-tight engagement with the exterior of such insulated conductor; and intermediate sections, between the middle section and respective end sections, that are recessed to provide space into which insulating material may be displaced to relieve pressure and minimise any tendency for the insulating material to be extruded outside the connector.

Description

1 2336950 1 ELECTRIC CONNECTORS This invention relates to electric

connectors for use on insulated conductors, primarily in overhead power line installations or other outdoor locations.

The places where the insulation of such conductors is stripped or penetrated to make connections for branch conductors, arc protection devices, earth bonds or the like always tend to develop concentrations of mechanical stress, and it is therefor particularly important that they should be protected if the atmospheric conditions present a risk of corrosion, as they commonly do. Present practice is to enclose the connection in a body of insulating and protective material, which is a significant expense (primarily in the cost of installation time) and adds to the weight and visual intrusiveness of the connection. The invention is based, in part, on the recognition that it is normally the conductor (as distinct from the connector) that needs to be protected, and its object is to provide such protection economically and compactly.

The connector in accordance with the invention comprises a ferrule (which is preferably longitudinally divided, in a way well-known per se, to allow it to be applied to a conductor without having access to either of its ends) comprising:

a middle section for compression to make connection with an insulated conductor; two end sections with bores capable of fluid-tight engagement with the exterior of such insulated conductor; and intermediate sections, between the middle section and respective end sections, that are recessed to provide space into which insulating material may be displaced to relieve pressure and minimise any tendency for the insulating material to be extruded outside the connector.

The middle section may be in the form of an ordinary compression fitting, requiring a portion of the insulation to 2 be removed from the conductor before the connector is applied, or it may be an insulation-piercing fitting, preferably of a kind that contacts the conductor without substantially deforming it: one such fitting is described in 5 GB2308239A of the present applicants and Preformed Line Products (Great Britain) Limited.

The end sections may in some cases achieve a sufficiently fluid-tight engagement with the insulated conductor simply by a force fit, but preferably they are compressed (to a small extent, compared with the middle section) to establish or improve sealing.

If desired, the end sections may be internally coated (or otherwise provided) with a plastic, resilient or viscous material for enhanced sealing, and if such material is soft enough it may also fill (or partly fill) the space in the middle sections. If they are substantially filled, and especially if with viscous rather than solid material, this space may be relieved to the atmosphere via passages of capillary dimensions (in relation to the viscous material) so that there need be no air contained within the connector.

By way of example, suitable materials include soft EVA formulations, polychloroprene and petroleum-based or silicone greases. Greases that swell on exposure to water may be advantageous.

The invention will be further described, by way of example, with reference to the accompanying drawings in which:

Figures 1 and 2 are perspective views of the main components of a connector in accordance with the invention for use without stripping insulation from the conductor; Figure 3 is an interior view of the component of Figure 1 and Figure 4 is an enlarged median transverse cross-section through the connector.

The main components of the connector are two half- 3 ferrules 1 and 2 (figures 1 and 2 respectively) of which the second has a lug 3 formed in one piece with it.

The lug may be of any conventional design, or may be replaced by an arcing horn or other desired fitting: it needs 5 no further description.

The half-ferrules 1 and 2 are generally alike. Each has a middle section 4 with co-operating insulation-piercing ribs 5, 6, the action of which will be explained later. At each end, they have end-sections 7 with plain smooth concave surfaces 8 which form, when the parts are assembled together, cylindrical bores that fit on the insulation of the conductor for which the connector is designed tightly enough to form a substantially water-tight seal around it, but not so tightly as to displace the conductor insulation to a significant extent.

These end sections 7 are connected to the respective middle sections 4 by intermediate sections 9 having recesses 10 in which insulation displaced longitudinally by the ribs 5 and 6 may be accommodated, to protect the insulation engaged by the concave surfaces 8 form distortion that might put the seal at risk.

The connector also includes a third component, a channel 11 (Figure 4) of uniform cross-section.

Halfferrule 1 is assembled with the channel in the factory, by endwise sliding; it is initially retained by ribs 12, and the assembly is lightly deformed by lateral squeezing to prevent it falling out in transit.

To apply the connector in the field to an insulated conductor (such as the conductor of an insulated-system likV transmission line), this assembly is placed on top of the insulated conductor. The second half-ferrule 2 is then slid into the channel 11, initially in the position shown in dashed lines, and a conventional compression tool used to apply squeezing forces to drive the half- ferrules together, without substantially distorting them, and to plastically 4 deform the channel 11 so that its edge portions 13 wrap around the underside of half-ferrule 2 to lock it, eventually, in the position shown in solid lines. The ribs 5, 6 are thus driven into the insulation 14, splitting it into four distinct lobes for which spaces are provided either side of each rib. They are dimensioned to fit tightly in contact with the metallic conductor 15 so as to make effective electrical contact with it without substantial distortion of either the conductor or the ribs, so minimising the concentration of longitudinal mechanical stresses in the conductor caused by the application of the connector.

The squeezing action may be sufficient to ensure a water-tight engagement between the contiguous faces of the half-ferrules 1 and 2, but preferably they are coated on appropriate faces with a water-swellable grease to give extra confidence in the seal (the particular gre ase used is a development product supplied by Dussek-Campbell Ltd under the designation DEV 023 and is thought to be based on petroleum jelly with the addition of a water-swellable powder, but other greases in current use in the electrical industry are suitable).

In an alternative example, the central section is replaced by a plain tube and the two half-ferrules have interlocking ribs and grooves to enable them to be slid into engagement with each other, eliminating the need for a channel member. This design requires the stripping of a section of the conductor, and the bore is such that the connector is initially an easy sliding fit over the insulation: the middle section is compressed in the usual way to make electrical contact with the conductor and the ends afterwards slightly compressed to establish the required seal to the insulation.

is

Claims (9)

1 An electric connector comprising a ferrule comprising:

a middle section for compression to make connection with an insulated conductor; two end sections with bores capable of flui d-tight engagement with the exterior of such insulated conductor; and intermediate sections. between the middle section and respective end sections, that are recessed to provide space into which insulating material may be displaced to relieve pressure and minimise any tendency for the insulating material to be extruded outside the connector.

2 A connector as claimed in claim 1 in which the ferrule is longitudinally divided.

3 A connector as claimed in claim 1 or claim 2 in which the middle section constituted an insulation-piercing fitting, of a kind that contacts the conductor without substantially deforming it.

4 A connector as claimed in any one of claims 1-3 in which the end sections are compressed to establish or improve sealing.

A connector as claimed in any one of claims 1-3 in which the end sections achieve a fluid-tight engagement with the insulated conductor simply by a force fit.

6 A connector as claimed in any one of claims 1-4 in which at least the end sections are internally coated (or otherwise provided) with a plastic, resilient or viscous material for enhanced sealing.

7 A connector as claimed in claim 6 in which the said material is soft and fills (or partly fills) the spaces in the middle sections.

8 A connector as claimed in claim 7 in which the said spaces in the middle section are substantially filled with a viscous material and are relieved to the atmosphere via passages of capillary dimensions (in relation to the viscous material) so that there need be no air contained within the 6 connector.

9 An electric connector substantially as described with reference to the drawings.

A connection to an insulated electric conductor comprising the connector claimed in any one of the preceding claims.