GB2232540A

GB2232540A - Electrical screen connectors

Info

Publication number: GB2232540A
Application number: GB8911266A
Authority: GB
Inventors: Roy Haley; Timothy Alan Luxford
Original assignee: New Chapel Electronics Ltd
Current assignee: TT Electronics Fairford Ltd
Priority date: 1989-05-17
Filing date: 1989-05-17
Publication date: 1990-12-12
Anticipated expiration: 2009-05-17
Also published as: GB2232540B; GB8911266D0

Abstract

A screen connector 9 for connecting to earth a screen 4 surrounding one or more insulated conductors 3 of a cable 2 is electrically conductive and has an inner sleeve portion 18 which surrounds the conductors 3 internally of an end part of the screen 4. An outer sleeve portion 20 of the screen connector 9 surrounds the end part of the screen 4 so that the end part of the screen is clamped between the inner and outer sleeve portions 18 and 20 to establish an electrical connection between the screen 4 and the screen connector 9 whilst permitting the conductors 3 to pass out of the end of the inner sleeve portion 18 for connection to a separate conductor connection 5. A plug-in connector portion 11 extends in the axial direction of the sleeve portions 18 and 20 and is plugged into an aperture 12 in an earthing plate 10 to establish an electrical connection between the screen connector 9 and the earthing plate 10 and to permit subsequent detachment of the screen connector 9 from the earthing plate 10. <IMAGE>

Description

"Electrical Screen Connectors" This invention relates to electrical screen connectors for connecting to earth a screen surrounding one or more insulated conductors of a cable, and to an electrical screen connection assembly comprising a plurality of screen connectors for connecting the screens of a multiscreen cable to earth.

The connection of the screens of a multiscreen cable to earth is currently carried out in a number of different ways. Generally each screen surrounds one or more insulated conductors, and it is necessary for all the screens to be electrically connected to a common earth connection point and for the individual conductors to be connected to the required contacts of the conductor connector. The connection of the screens to the common earth connection point may be carried out by connecting a wire between the screens and the earth connection point, the wire being soldered or crimped to each screen.

Alternatively all the screens may be wrapped together with a metal bandage which is then connected to the earth connection point. However, all these earth connection methods suffer from the fact that they are not completely reliable in practice. Also it can be difficult with these methods to ensure that the lengths of the conductors which are unscreened are the same so as to ensure that the same external level of interference is experienced by each conductor.

It is an object of the invention to provide a generally improved electrical screen connector, and an electrical screen connection assembly incorporating a plurality of such screen connectors.

According to the present invention there is provided an electrical screen connector for connecting to earth a screen surrounding one or more insulated conductors of a cable, the screen connector being electrically conductive and having an inner sleeve portion adapted to surround the conductors internally of an end part of the screen, an outer sleeve portion adapted to surround the end part of the screen so that the end part of the screen is clamped between the inner and outer sleeve portions to establish an electrical connection between the screen and the screen connector whilst permitting the conductors to pass out of the end of the inner sleeve portion for connection to a separate conductor connector, and a plug-in connector portion extending in the axial direction of the sleeve portions and adapted to be plugged into an aperture in an earthing plate in said axial direction to establish an electrical connection between the screen connector and the earthing plate and to permit subsequent detachment of the screen connector from the earthing plate.

The plug-in connector portion is preferably integrally formed with the inner sleeve portion, and the outer sleeve portion is a separate piece which may be slid over the inner sleeve portion and clamped thereon, for example by crimping, so as to trap the end part of the screen between the inner and outer sleeve portions.

The plug-in connector portion may be a pin attached to a peripheral part of the inner sleeve portion and extending parallel to, and offset from, the axis of the inner sleeve portion.

The plug-in connector portion may be a split pin having flanges at its free end such that, when plugged into an aperture in the earthing plate from one side, the pin passes through the aperture and the flanges spring outwardly to engage the earthing plate on the opposite side of the plate so as to hold the pin within the aperture.

The invention also provides an electrical screen connection assembly comprising a plurality of screen connectors as described for connecting to the screens of a multiscreen cable, and a common earthing plate having a plurality of apertures for receiving the plug-in connector portions of the screen connectors to collectively connect the screens to earth.

The common earthing plate preferably includes a central hole for the passage of the insulated conductors of the cable for connection to the separate conductor connector beyond the earthing plate.

The common earthing plate may additionally include one or more arcuate slots concentric with the central hole for the passage of the insulated conductors.

The screen connection assembly may additionally include a shell comprising two parts which may be screwed together to surround the screen connectors and the earthing plate, one of the parts having an aperture for passage of the cable and the other part having an aperture for passage of the conductors. The shell may be adapted to be attached to the conductor connector by screwing.

In order that the invention may be more fully understood, a preferred screen connection assembly according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the assembly; Figure 2 is an exploded view of a screen connector of the assembly, partially in section; Figure 3 is view of a screen connector connected to the common earthing plate of the assembly; Figure 4 is a front view of the common earthing plate; and Figure 5 is a section of the common earthing plate taken along the line V-V in Figure 4.

The screen connection assembly 1 shown in Figure 1 is provided for connection to a multiconductor cable 2 incorporating a plurality of insulated conductors 3, the conductors 3 being arranged in pairs and each pair of conductors 3 being sheathed by a respective electrically conductive screen 4. Furthermore, for connection to a standard conductor connector 5, the insulation at the end of each conductor 3 is stripped and the conductor 3 is terminated by a standard pin contact 6, for example by crimping. Each conductor contact 6 is engaged within a respective contact socket 7 in the connector 5 in conventional manner, as indicated by the broken lines 8 in the figure.

Furthermore each screen 4 is stripped back from the ends of the conductors 3 and is terminated by a respective screen connector 9 in a manner which will be described more fully below. Each screen connector 9 is then engaged with a common earthing plate 10 by plugging a connector portion 11 into a respective aperture 12 in the earthing plate 10, as indicated by the broken line 13 in the figure. The conductors 6 may then be passed through a central hole 14 or arcuate slots 15 in the earthing plate 10 prior to connection to the conductor connector 5.

The assembly 1 has a backshell 16 which receives the earthing plate 10 and which may be screwed onto the conductor connector 5, and a follower nut 17 which surrounds the cable 2 and which may be screwed onto the backshell 16.

The manner in which the screen connector 9 is connected to the screen 4 and to the earthing plate 10 will now be described in more detail with reference to Figures 2 and 3. The screen connector 9 comprises an inner sleeve portion 18 having a flange 19 to which the plug-in connector portion 11 is attached, and an outer sleeve portion 20. In order to connect the connector 9 to the end part of the screen, the outer sleeve portion 20 is threaded onto the screen so that it is clear of the end part, and the end part of the screen is then drawn over the outer surface 21 of the inner sleeve portion 18 with the associated insulated conductors being drawn through the inside of the inner sleeve portion 18.The outer sleeve portion 20 is then drawn over the end part of the screen and crimped so as to trap the end part of the screen between the inside surface 22 of the outer sleeve portion 20 and the outside surface 21 of the inner sleeve portion 18.

As may be seen in Figures 2 and 3, the plug-in connector portion 11 is in the form of a split pin having a slot 23 extended for the major part of the length of the pin and opening on opposite sides of the pin. The pin also has flanges 24 at its free end. After connection of the connector 9 to the screen, the connector portion 11 is plugged into an aperture 12 of the earthing plate 10 from one side so that the pin passes through the aperture 12 and the flanges 24 spring outwardly to engage the plate 10 on the opposite siffie Di the- p1ate as shown in Figure 3.

The connector portion 11 may subsequently be released from the aperture 12 if required by use of a special release tool.

As shown in Figures 4 and 5, the earthing plate 10 is provided with three arcuate slots 15 concentric with the central hole 14, and two series of apertures 12 disposed respectively radially inwardly and radially outwardly of the slots 15. Conductors associated with connectors 9 plugged into the radially outer apertures 12 are passed through the slots 15, whereas conductors associated with connectors 9 plugged into the radially inner apertures 12 are passed through the central hole 14.

In a variant of the illustrated earthing plate 10, further apertures 12 and/or further slots 15 are provided radially outwardly of the apertures 12 and slots 15 shown in Figures 4 and 5.

In a modification of the illustrated connection assembly, the plug-in connector portion 11 of each screen connector 9 is replaced by a flanged extension of the inner sleeve portion which is capable of being plugged into a suitable aperture in the earthing plate. In this case the earthing plate will require only apertures for reception of such plug-in connector portions (and will not require a central hole 14 or slots 15) since the conductors will pass through the earthing plate within the sleeve form connector portion.

In a further modification of the illustrated connection assembly, the common earthing plate 10 is insulated from the two-part shell within which it is installed, so that the screen connectors are connected together by the earthing plate 10 but are insulated from the surrounding shell. A connection is made from the earthing plate 10 to an earth contact of the conductor connector 5 using a plug-in connector portion plugged into an aperture in the earthing plate 10 and connected by an insulated conductor to the earth contact of the conductor connector 5.

The above-described connection assemblies provide reliable collective screen terminations in such a manner that the unscreened lengths of the conductors may be maintained substantially equal.

Claims

1. An electrical screen connector for connecting to earth a screen surrounding one or more insulated conductors of a cable, the screen connector being electrically conductive and having an inner sleeve portion adapted to surround the conductors internally of an end part of the screen, an outer sleeve portion adapted to surround the end part of the screen so that the end part of the screen is clamped between the inner and outer sleeve portions to establish an electrical connection between the screen and the screen connector whilst permitting the conductors to pass out of the end of the inner sleeve portion for connection to a separate conductor connector, and a plug-in connector portion extending in the axial direction of the sleeve portions and adapted to be plugged into an aperture in an earthing plate in said axial direction to establish an electrical connection between the screen connector and the earthing plate and to permit subsequent detachment of the screen connector from the earthing plate.

2. A screen connector according to claim 1, wherein the plug-in connector portion is integrally formed with the inner sleeve portion, and the outer sleeve portion is a separate piece which may be slid over the inner sleeve portion and clamped thereon so as to trap the end part of the screen between the inner and outer sleeve portions.

3. A screen connector according to claim 1 or 2, wherein the plug-in connector portion is a pin attached to a peripheral part of the inner sleeve portion and extending parallel to, and offset from, the axis of the inner sleeve portion.

4. A screen connector according to claim 1, 2 or 3, wherein the plug-in connector portion is a split pin having flanges at its free end such that, when plugged into an aperture in the earthing plate from one side, the pin passes through the aperture and the flanges spring outwardly to engage the earthing plate on the opposite side of the plate so as to hold the pin within the aperture.

5. An electrical screen connection assembly comprising a plurality of screen connectors according to any preceding claim for connecting to the screens of a multiscreen cable, and a common earthing plate having a plurality of apertures for receiving the plug-in connector portions of the screen connectors to collectively connect the screens to earth.

6. An assembly according to claim 5, wherein the common earthing plate includes a central hole for the passage of the insulated conductors of the cable for connection to the separate conductor connector beyond the earthing plate.

7. An assembly according to claim 6, wherein the common earthing plate additionally includes one or more arcuate slots concentric with the central hole for the passage of the insulated conductors.

8. An assembly according to claim 5, 6 or 7, which additionally includes a shell comprising two parts which may be screwed together to surround the screen connectors and the earthing plate, one of the parts having an aperture for passage of the cable and the other part having an aperture for passage of the conductors.

9. An assembly according to claim 8, wherein the shell is adapted to be attached to the conductor connector by screwing.

10. An electrical screen connector for connecting to earth a screen surrounding one or more insulated conductors of a cable, the screen connector being substantially as hereinbefore described with reference to the accompanying drawings.