DE8716475U1 - Electrical cable - Google Patents

Description

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DESCRIPTION(J N G

The invention relates to the connection of two electrical cables.

An electrical cable, such as a power cable, is often of indefinite length so that it can be cut to lengths when and where required. However, at other times it is advantageous for such a cable to be supplied in a predetermined length and is therefore terminated at both ends, e.g. with a plug at one end for the supply of electrical power and a socket at the other end for the reception of a further plug. Electrical cables containing a conductive polymer material are usually supplied without termination; terminals _{, cable} boxes and end seals are supplied as separate components for connection in situ. Examples of self-regulating heating cables, conductive polymer materials and sensing cables are described in U.S. Patents 3,218,384, 3,296,364, 3,861,029, 4,072,848, 4,117,312, 4,185,621, 4,271,350 and 4,309,597 and in EP-A-0133748. In one commercially available cable, a termination is provided for TRACETEK heating cables from Raychem. The termination consists of two separate parts, a first part which is glued to the cable and has sockets which connect to corresponding sockets on its busbars, and a second part which has an end cap which is screwed onto the first part which connects the busbars.

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And therefore enables the cable to function. To extend the measuring cable, the end cap is unscrewed and a plug at the end of an extension cable engages the exposed plug connections.

The extension of these cables and other cables containing conductive materials is carried out at the installation site and may require the presence of an electrically trained person to comply with regulations and can therefore be a time-consuming operation. In addition, the termination or splicing of cables of any type at the installation site can be difficult depending on the environment, size and accessibility of the work area.

The invention therefore relates to an electrical cable, such as a power cable, heating cable, measurand cable or data transmission cable, and in particular, although not exclusively, to a cable with one or more conductors embedded in conductive polymer material, which enables it to be obtained in longer lengths in a simple and safe manner. According to the invention, an electrical cable is therefore provided, which comprises: at least one elongated conductor surrounded by electrical insulating material; a plug part, which has an insulating body which seals one end of the cable against the environment, and which has at least one conductive termination which is electrically connected to the conductor or to other conductors and which protrudes from the insulating body; and a one-piece socket part which

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seals the other end of the cable from the environment URd has at least one conductive socket, each socket being arranged to receive at least one end of a plug part upon removal of a portion of the socket part.

Removal of a portion of the socket to accommodate the termination can be easily accomplished by a cover or other sealing member through which the termination penetrates.

Furthermore, a splice part is provided which is suitable for use together with two or more and preferably three cables according to the invention, the splice part comprising an insulating body, at least one conductive termination projecting therefrom and at least one, preferably two sockets which are connected to the termination, each of the sockets being sealed against the environment.

The invention therefore provides a cable which is sealed at the end by an integral component but which is easily accessible for extending a standard length by a further standard length.

The cables connected in this way to form a system need not be of the same length or of the same type. For example, a relatively short power cable according to the invention can be connected to a relatively long heating cable or measuring cable, or two heating or measuring cables can be connected to a simple power cable that extends over

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extends beyond an area where heating or sensing is not required* Such standard cables and splices can therefore be assembled on site to form a system that meets the specific requirements*

Due to the simplicity of the parts sealing the cable ends, a slim profile is achievable in contrast to the bulky cable boxes that have been commonly used.

At least some of the terminations and sockets can be oriented orthogonally to each other so that the cables thus connected form a T-shaped splice. The sealing of the sockets of the splice is advantageously carried out in the same way as the sealing of the sockets of the cables.

The splice itself can be sealingly attached to one end of the cable in place of the plug or socket portion.

The invention therefore enables the provision of predetermined lengths of cable, the cable being provided with a plug part at one end and a sealed socket part at the other end. Two or more such cables can be connected end to end by engagement of corresponding plug and socket parts simply by mechanically breaking the seal of a socket part, the seal being arranged to close the subsequently formed connection. The connection does not require an electrical engineer to make it, so that cables can be connected by other persons at the required time.

available people. For example, during the construction of buildings, carpenters, plumbers and electrical engineers can be present at different times; by means of the invention, electrical cables can be installed at the desired stage of construction in the absence of electricians.

The sealing against the environment is such that the access of dust, water and moisture from the environment to the insulated cable conductor is prevented.

The sealing of the socket part can be achieved by an insulated cap, which is tightly fitted on the cable. The end cap can be

be cut off in whole or in part or

broken in such a way that the sockets are exposed to receive the terminations. The closure may be provided by a sealing material such as a gel which is disposed in the sockets and/or the end cap. The term gel is used herein to mean a swollen, cross-linked polymer material, e.g. a matrix of cross-linked rubber containing oil. If a sealing material is used, penetration through the terminations must not destroy the closure/seal. Advantageously, a sufficient amount of sealant is provided so that no additional material is required to seal the mating plug and socket parts. Alternatively, the mechanical connection of plug and socket is provided for sealing without the need for additional sealing material.

The socket part can have two or more sockets in electrical connection with one or each conductor of the cable such that two or more plugs of corresponding cables are enclosed by a single socket or socket part in order to create, for example, a T-shaped splice.

Advantageously, the plug and socket are physically arranged such that they only engage in an orientation that is such that a correct electrical connection between the cables is ensured.

In some applications, it is necessary for a connection between two cables according to the invention that the connection is not breakable, i.e. that when the connection is made manually by inserting the plug into the socket, the parts cannot be manually pulled apart with adequate force without mechanically destroying the connection. For this purpose, the plug and socket parts are arranged so that they mechanically lock together in a suitable manner. For example, the insulating part of the socket can have a flexible, advantageously annular part, while the insulating body of the plug has a cooperating, advantageously annular groove, which acts as a snap-fit device. In another embodiment, the snap-fit can be achieved by a groove on a termination of the plug and a cooperating spring in the corresponding socket.

Br£iridUrtgsge>compliant cables can be supplied in pre-

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manufactured to the same but different lengths and can be assembled end to end in a modular fashion to form different lengths. By attaching the plugs and sockets to the cable lengths under controlled conditions rather than a potentially hostile environment, batches of errors are reduced during assembly and when making a cold splice or fitting a cable box.

The invention has particular, although not exclusive, application to electrical cables having one or more, e.g. two, conductors embedded in partially conductive polymer material, e.g. in polymer material filled with carbon. The conductive polymer material may be a PTC material (positive temperature coefficient of resistance) so that the cable is, as mentioned above, a self-regulating heating cable. Alternatively, a measuring cable may be used, e.g. a sensor cable sold by Rayhern under the trade name "TRACETEC". Such cables are elongated and flexible and can thus be easily guided through rooms in buildings and around obstacles.

Examples of embodiments of the cable and cable connections are described below with reference to the attached drawings:

Figures 1 and 2 show a heating cable in plan and side view; Figure 3 shows a plan view of the connection of two cables, which are shown in Figures 1 and 2 respectively, and Figures 4 and 5 show a splice part in a schematic plan and side view

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for use with the cables shown in Figures 1 and 2.

Figures 1 and 2 show a self-regulating heating cable 2 (type "AUTOTRACE" from Raychem) with a nominal length of 10 m with a pair of longitudinally running metal conductors (4) embedded in conductive polymer material with PTC behavior (not shown) and surrounded by an outer insulating sheath made of polymer material ·\-=·1 (6). The conductors (4) are connected to each EnJe

of the cable (2) via the PTC material. A plug

! (8) with an insulating body is at one end of the

cable (2) and a pair of conductive

] degrees (10) that are equivalent to

} of the ladders (4) is connected to the

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A termination (12) with an insulating body is

other end of the cable (2) and a pair of conductive sockets (14), each connected to

i ^; corresponding versions of the ladder (4) are

The sockets (14) are filled with gel, with a pair of end caps (16) enclosing the gel. The sockets (14) are designed to

Keys (10) of a corresponding cable (2) in

! tight press fit.

Figure 3 shows the connection between the terminations (10) of the plug (8) of a cable (2) and the sockets (14) after removing the end caps (16) of a

corresponding cable (2) with some gel (18) which is

the sockets (14).

s The plug (8) and the termination (12) are in the same

seat so that they cannot be disassembled

can be pulled apart. For this purpose, the closure (12) includes a spring (not shown) attached to its outer surface and projecting beyond it. The plug (8) has an annular groove on its outer surface. When the plug (8) and closure (12) interact, as shown in Fig. 3, the plug (8) and closure (12) are closed and ^closed :

Figures 4 and 5 show a terminal (24) for forming a T-shaped splice between three cables (2) (not shown) having a generally cubic insulator body from one face of which protrudes a pair of conductive terminations (22). Two pairs (24, 26) of conductive sockets are embedded in the insulator body, one socket of each pair being electrically connected to a corresponding socket of the termination (22). The sockets (24) extend towards a face of the terminal (20) opposite the face from which the terminations (22) protrude, the sockets (26) extend towards an orthogonal face. Each of the sockets is sealed with a gel and closed by an end cap (28). In use, the end caps (28) are cut off and the pins (10) of the plugs (8) of the two cables (2) are inserted into the corresponding pairs (24, 26) of the sockets. The terminations (2 2) are inserted into the sockets (14) of the termination (12) of another cable. This creates a T-shaped splice with two cables aligned and a third extending orthogonally to them.

The terminal (20) can be formed in one piece with the cable (2). The terminal ends (22) can then

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Connected to the corresponding ends of the cable conductors (4) at the sides. ₄ In this way, two plugs (8) and two additional cables (2) can be connected to the original cable (2).

Claims (9)

CLAIM FOR PROTECTION 1. Electrical cable containing a) at least one elongated conductor surrounded by electrical insulating material b) a plug part with an insulating body sealing one end of the cable against the environment c) at least one conductive termination connected to the conductor, which projects beyond the insulating body, characterized in that the cable has a one-piece socket part (12) which is attached to the other end of the cable (2) in a manner sealing against the environment and has at least one conductive socket (14) which is arranged in such a way that, when the part (16) of the socket part (12) is removed, it can accommodate at least one termination (10) of a plug part corresponding to the plug part (8). 2. Cable according to claim 1, characterized in that an insulated cap (16) enclosing each socket (14) is provided as a seal. 3. Cable according to claim 1 or 2, characterized in that the sealing is effected by a sealing material. 4. Cable according to claim 3, characterized in that the sealing material contains or consists of a gel. 5. Cable according to any one of claims 1 to 4, characterized in that the socket part (2C) has two or more sockets (24, 26) in electrical connection with each conductor (4) of the cable (2), two or more corresponding plug parts (8) being electrically connectable to the socket part (20). 6. Cable according to one of claims 1 to 5, characterized in that the plug-in socket part (12) and \ the plug part (&) are arranged in such a way that s, engagement socket part (12) and corresponding plug part (8) interlock. 7. Cable according to one of claims 1 to 6, characterized in that each conductor (4) is embedded in a polymer material containing conductive particles. 8. Cable according to one of claims 1 to 7, characterized in that a PTC heating cable is present. 9. Cable according to one of claims 1 to 6, characterized in that it is a measuring cable.