GB2246923A

GB2246923A - Cable identification and routing confirmation using a thermal technique

Info

Publication number: GB2246923A
Application number: GB9017303A
Authority: GB
Inventors: David Leslie Edward Hobby; Richard Martin Howard Smith
Original assignee: Roke Manor Research Ltd
Current assignee: Roke Manor Research Ltd
Priority date: 1990-08-07
Filing date: 1990-08-07
Publication date: 1992-02-12
Anticipated expiration: 2010-08-07
Also published as: GB9017303D0; GB2246923B

Abstract

Individual cables of an enclosed cable loom are easily identified by 'tagging' with a thermal marker. At an access point of a cable to be identified, a small amount of the outer insulation 9 is removed by cutting or scraping. A small pipe 12 is inserted into the centre 10 of the cable and a gastight seal 13 is formed at the interface. A proprietary freezer spray, which is commonly used in the electronics industry, can then be injected directly into one end of the cable under test whereby the other remote end is consequently cooled so as to be identified and distinguished from other cables in the loom by means of a thermal imager. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO CABLE IDENTIFICATION This invention relates to cable identification, and more especially it relates to techniques for identifying at one end of a cable loom, comprising a plurality of cables, an individual cable, to which access is available at a location remote from the said one end of the loom.

Cable looms usually comprise a plurality of cables, each cable comprising a conductor formed by one or more wires and each conductor being enshrouded in an insulative covering or sheath.

Such looms not uncommonly comprise a multiplicity of cables. In order to identify a particular cable so that it can be selected from the loom, colour coding and/or sleeve markers are quite commonly used whereby a selected cable can be identified and if necessary separated from other cables of the loom at one end thereof, for the purposes of making an electrical test connection for example.

After installation of a loom however, it is not always easy to gain access to the cables of the loom for identification purposes and thus identification marker sleeves and/or colour codes are not always easily seen or accessible. Moreover in looms comprising large numbers of cable there are obvious practical difficulties associated with cable marking especially when the cables are relatively small in diameter.

The present invention seeks to provide for the identification of a cable from a loom as aforesaid, wherein the problems associated with identification hereinbefore mentioned are at least in part obviated.

According to the present invention a method of identifying a selected cable in a loom comprising a plurality of cables having at least one conductor enshrouded by an insulative sheath, comprises injecting into the selected cable at a first location between said sheath and said conductor, fluid at a pressure above ambient pressure and at a temperature which is sufficiently different to ambient temperature for the selected cable at a second location remote from said first location thereof to be detectable and distinguishable from other cables of the loom by means of a thermal imager.

The fluid might conveniently be gas available commercially as a proprietary freezer spray which is injected into the cable at said first location via a gas tight injection seal whereby the cable is cooled along its length so that at the said second location, cooling is apparent whereby the selected cable is detectable and distinguishable from other cables by means of the thermal imager.

The insulative sheath may be at least partly removed at said second location.

One embodiment of the invention will now be described with reference to the accompanying drawings wherein; Figure 1 is a somewhat schematic sectional side view of apparatus for carrying out a method according to the present invention and, wherein; Figure 2 is an enlarged sectional side view of a part of the apparatus shown in Figure 1.

Referring now to the drawings, a cable loom 1 comprises a plurality of individual cables such as cables 2 and 3 for example.

The cables 2 and 3 are enclosed within an area 4 to which access is not readily available. In one example the cables 2 and 3 of the loom may be connected to sensors in the area 4 which may be a radioactive environment for example. Those ends of the cables comprising the loom 1 which emerge within the area 4 such as ends 2a and 3a of the cables 2 and 3 for example are arranged to be visible through a window 5 whereby they can be inspected with a thermal imager 6.

At a cable access location 7 outside the area 4, a cable 8 of the loom 1 is selected as shown in the enlarged view, Figure 2. The cable 8 maybe selected for a variety of reasons such as because of accidental damage to the loom 1 or for test purpose for example. As shown in Figure 2, the cable comprises an insulative outer sheath 9 and a plurality of conductors 10. A small incision 11 is made in the insulative outer sheath 9 and a gas injection pipe 12 is inserted into the incision 11. The gas injection pipe 12 is enclosed in a gas tight seal 13 which is sealed against the insulative sheath 9 whereby an inert commercially available freezer gas from a pressurised container can be injected under pressure into the cable such that the cable is cooled along its length.

Thus if for example the selected cable 8 of Figure 2 were the other end of the cable 2, of Figure 1, the end 2a would be noticeably cooled by reason of the injection of the gas into the cable 2, and this cooling effect would be identifiable by means of the thermal imager 6 whereby the particular cable selected can be identified. It will be appreciated that an important advantage of a cable identification technique as hereinbefore described, is that it will cause no disturbance within an area such as the area 4 as shown in Figure 1 to which access is not easily achieved. Furthermore since no electrical connection is made to the cable there will be no disturbance to systems which maybe connected to the cable. Additionally, the method is easy to implement, reliable and can be rapidly applied.

It will be apparent that various modifications may be made to the apparatus described without departing from the scope of the invention and for example a liquid may be injected through the pipe 12, the character of the liquid being chosen such that it boils into a gas when expanding at ambient temperature within a cable under test.

Claims

1. A method of identifying a selected cable in a loom comprising plurality of cables having at least one conductor enshrouded by an insulative sheath, comprising injecting into the selected cable at a first location between said sheath and said conductor, fluid at a pressure above ambient pressure and at a temperature which is sufficiently different to ambient temperature for the selected cable at a second location remote from said first location thereof to be detectable and distinguishable from other cables of the loom by means of a thermal imager.

2. A method as claimed in claim 1 wherein the fluid is a gas available commercially as a proprietary freezer spray which is injected into the cable at said first location via a gas tight injection seal whereby the cable is cooled along its length so that at the said second location, cooling is apparent whereby the selected cable is detectable and distinguishable from other cables by means of the thermal imager.

3. A method as claimed in claim 1 or claim 2 wherein the insulative sheath is at least partly removed at said second location.

4. A method as claimed in any preceding claim and as hereinbefore described with reference to the accompanying drawings.

5. Apparatus when used for carrying out the method of any preceding claim comprising means for injecting the fluid and a thermal imager for detecting the said selected cable.