GB2166914A - Electrical conductor system - Google Patents

Abstract

A support rail 1 for electrical terminal blocks or modules, of standard channel section with flanges for mounting the modules, has in its channel longitudinal conductors such as busbars which are accessible to connecting elements provided on the modules, for example through longitudinal slots 6 in an insulating body for accommodating the busbars 7. The modules have matching contacts, which make contact with the busbars automatically when the modules are mounted on the rail. The conductors may be formed by tracks on a printed circuit board. <IMAGE>

Description

SPECIFICATION Electrical conductor system This invention relates to means for making electrical connections between terminal units.

The use of support bars or support rails, onto which electrical terminal blocks are detachably mounted. Such terminal blocks commonly include additional circuit components such as fuses, switches and electronic circuitry.

Particularly common, is the use of support mounting rails of channel-shaped cross section, with outwardly turned symmetrical flanges for inwardly turned asymmetrical flanges, onto which the terminal units are clipped by means of springs or the like in the terminal units.

It is now common practice to use such support rails to carry insulating housings or blocks which incorporate control and/or signal circuitry. The individual blocks are modular so as to form a more or less uniform assembly when they are mounted side by side on the support rail. By using a suitable combination of such blocks, it is relatively easy to build up a neat and compact assembly of supply and control circuitry for domestic and industrial uses.

A disadvantage of existing circuit assembly systems of the above mentioned kind, is that conductors have to be provided to make the necessary interconnections between the individual blocks, for example using ordinary single or multi-core cables. In one known system, the support rail carries individual sockets into which the circuit blocks are plugged, and the sockets are interconnected by means of flat ribbon cable. This arrangement is inconvenient and the flat ribbon cable is vulnerable to damage.

An object of the present invention is to provide an improved arrangement for interconnecting circuit blocks mounted on a flanged supporting rail.

According to the present invention, a channel-section support rail provided with flanges for the mounting of circuit blocks on the rail, is provided with a plurality of longitudinal insulated electrical conductors mounted in the channel of the rail, the conductors themselves being accessible.

For use with such a rail there are to be provided terminal blocks or circuit blocks (hereinafter called modules) incorporating electrical contacts, arranged so as to make contact with individual conductors in the rail, when the modules are mounted onto the rail.

With such an arrangement, the necessary electrical connections among the modules can be made automatically when the modules are mounted in place, and furthermore the interconnecting conductors are well protected against accidental damage.

In one embodiment of the invention, metal bus bars, for example of rectangular or square cross section, are housed or embedded in a strip of insulating plastics material, which is provided with longitudinal slots or channels through which a contact spring, finger or the like of a terminal or circuit module can extend into contact with the respective bus bar.

In another embodiment of the invention, the channel accommodates a circuit board, which may be rigid or flexible, with conducting tracks on its upper surface in a desired number and arrangement. As the tracks do not have intervening insulating barriers, this arrangement may be suitable only for low voltages and currents.

For use with the last mentioned channel and circuit board, a module may be provided with a connecting strip arranged to extend across the channel, and consisting of conducting laminae alternating with insulation at a pitch not greater than that of the circuit board conductors. A connector of this nature can be used to provide connections between a variety of conductor strip layouts and module conductors. The connector may be separate from both the circuit board and the conductors in the module for maximum versatility.

In yet another embodiment, longitudinal conducting tracks or bars may project from insulation, within the channel, to make contact with connectors on modules, for example connector fingers projecting so as to engage respective side faces of the conductors The insulation may be integral with or constitute the support rail.

The invention will be further described by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a support rail provided with conductors, in accordance with the invention, Figure 2 shows a cross section of the rail, Figure 3 shows a terminal block assembly mounted on the support rail, Figure 4 illustrates an alternative embodiment of the invention, and Figure 5 illustrates a further embodiment of the invention.

Figure 1 shows a metal support rail 1 of channel section with symmetrical outwardly turned flanges 2. Such rails are well known.

They are made with standard dimensions so that a range of modules comprising terminal blocks and circuit blocks can be clipped onto the flanges by means of notches and springloaded elements or springs on the bottoms of the modules or by means of integral resilient plastics locking elements on the modules themselves. Alternatively the modules may be provided with separately attached feet which secure the modules over the flanges of the rail.

The channel portion 3 of the rail is substantially filled by a moulded insert strip 4 of plastics or other insulating material. The plastics insert strip 4 is held in place mechanically, by adhesives, or by being moulded or extruded into the channel.

The insulating insert contains a number of longitudinal channels 5 each of which communicates with the exposed surface of the insert through a continuous longitudinal slot 6. A square-section electrical conductor bar 7 is placed in each channel 5. For example, the bars may be slid into the channels in a previously moulded insert strip, or the plastics material may be moulded or extruded round the conductor bars to form an integral assembly of insulation and conductors.

The insulating strip and conducting bars extend over the entire length of the rail, which can be cut to any desired length according to the intended use.

In the illustrated arrangement, there are five conductors, namely three for carrying power and two for carrying signals, but of course the specific requirements and allocation of use of the conductors may vary according to the desired application. Different numbers of conductors may be provided. There may be a range of rails containing different numbers of conductors, alternatively there may be a range of insert assemblies (plastic strip and conductors) with different numbers of conductors, capable of being fitted into standard channel section rails according to the desired application.

Typically, the insulating material and conductors are designed for low voltage applications, up to 660 volts three-phase, to 5 amps per conductor.

In use, modules which may contain various different electrical components and circuit elements, for example printed circuit boards and/or integrated circuits for control and signalling operations, are fitted onto the rail, gripping the flanges 2, as described above. The illustrated modules are provided with integral or separately attached feet with flanges 13 securing the modules over the flanges of the mounting rail. Each such module has an insulating moulded plastics housing to accommodate its terminals and other circuit components. In general, the modules have a common height and depth but may have different thicknesses (along the length of the rail).

Thus, when mounted on the rail side by side they form a neat modular assembly, for example as shown schematically in Figure 3 which illustrates five relatively narrow modules indicated by reference numeral 8, and one wide module 9. Each of these modules is provided with one or more terminals for electrical connections, for example screw terminals for wires, or multi-pin plug and socket connectors.

Each module also has, in its base, mouldedin electrical contacts which project so as to make contact with the respective conductor bars 7 when the module is mounted on the rail. To ensure good contact, these contacts may be resilient, or they may be mounted resiliently in the module. These contacts are connected, within the terminal, to the signal circuit components or current-carrying components of the terminal module.

Power and signal connections to the conductor bars 7 can be made by way of one or more such modules, but alternatively we may provide an input connector 10 comprising a multi-socket member designed to make contact with exposed ends of the conductor bars 7, and provided with signal cables 11 and power cables 12.

To protect those parts of the conductor bars that are not covered by the modules, cover plates 14 may be provided, which can be slid or clipped over the flanges of the rail.

The cover plates may be made in the form of long strips, being cut by the user to the required length to cover the exposed regions of the conductors.

The terminals in the modules are connected to circuitry or equipment to be powered and controlled, by suitable cables. Power and/or signals are fed into the conductor bars and are transmitted through the modules with or without processing therein. By means of the signalling busbars, for example, it is possible to transmit coded signals (analogue or digital) to operate decoders built into the modules and thereby to control, for example, the transmission of power through the modules to associated pieces of equipment. This can provide for remote control of plant and equipment for example in generating installations, petrochemical installations, oil rigs and so on.

The described system provides a quicker and simpler way of making up a terminal distribution system, and can considerably reduce the wiring time, compared with known arrangements of terminal blocks and interconnecting conductors. The individual modules are mounted directly onto the rail, and the act of mounting them automatically makes the necessary connections with the conductor bars, without any need for an intermediate base unit or socket as in known rail-mounting systems and without any need for attaching interconnecting cables.

Figure 4 illustrates schematically, in perspective, a support rail and busbar system in which the rail accommodates a printed circuit board 15, of rigid or flexible construction, which has on its upper surface parallel longitudinal conducting tracks 16 attached to the circuit board in any suitable way. The circuit board is secured in the metal channel by adhesive or other suitable means. The conducting tracks 16 form busbars for power and/or signal transmission.

An electronics module has a housing (not shown) incorporating one or more printed circuit boards 17 on which are conductors 18 the positions of which cross the width of the module correspond to the positions of the tracks 15 across the channel. To provide conducting paths between the tracks 16 and the tracks 18, the module is provided with one or more connecter strips 19, held in the position in the base of the module by the module housing moulding or by a removable foot used to attach the module to the rail.

The strip 19 consists of a non-conducting elastomeric core, with rings of conducting material set along the length of the core. The rings are insulated from one another by intervening insulation or by air gaps. When the module is mounted on the rail, the conducting rings make contact with the tracks 16 of the rail and also with the tracks 18 of the module thereby connecting the tracks 16 with the tracks 18. Because of the elastomeric nature of the core of the strip, adequate contact pressure between the tracks and the rings can be ensured even if there are local irregularities in the tracks or circuit boards, as the strip 19 can accommodate itself to the surface profiles of the circuit board 15 and the circuit board or boards in the module 17.

Figure 5 shows schematically, it cross section, an embodiment of the invention in which the channel of the rail 1 contains an insulating support strip 20, with upstanding longitudinal insulating strips 21 spaced across its width.

These strips may be integral with the strip 20, or attached to it for example by being set on edge in grooves in the strip 20. Each strip 21 has a conducting track on one or both sides. The module has in its base an insulating connector block 22 from which project spring contact fingers 23 corresponding in position to the faces and conducting tracks of the strips 21. When the module is mounted on the rail, these fingers 23 penetrate the gaps between the strips 21 to make contact with the conducting tracks on these strips and thereby to provide conductive paths between the conducting tracks and the circuit elements of the module. The connector block is held in the base of the module by the housing moulding or by a removable foot of the module.

Claims (9)

1. A channel-section support rail provided with flanges for the mounting of electrical or electronic modules on the rail, and having, in the channel of the rail, a plurality of longitudinal insulated electrical conductors accessible for making contact with the contacts provided on modules to be mounted on the rail.

2. A rail as claimed in claim 1 in which the conductors are set into an insulating strip which is retained in the channel, the said strip having longitudinal slots through which the conductors are accessible.

3. A rail as claimed in the claim 1 in which the conductors are tracks provided on a circuit board disposed in the channel.

4. A rail as claimed in claim 3 in combination with a module incorporating a contact element in the form of a flexible eiongate body provided with exposed mutually insulated conducting members, for providing contact paths between the conducting tracks of the circuit board, and conducting elements of the module.

5. A rail as claimed in claim 1 in which the conductors are conducting elements provided on respective side surfaces of upstanding longitudinal insulating strips mounted in the channel, for receiving contact fingers of modules.

6. A rail as claimed in any of the preceding claims in combination with modules having detachable feet for mounting the modules on the rail.

7. An electrical installation or applicance incorporating at least one rail according to any of the preceding claims, a plurality of modules mounted on the rail, means transmitting operating power through at least one said conductor and means transmitting control signals through at least one other said conductor.

8. An electrical installation or appliance incorporating at least one rail according to any of claims 1 to 6, a plurality of modules mounted on the rail, means transmitting operating power through at least one said conductor and means transmitting control signals through the same conductor(s).

9. Electrical apparatus, substantially as herein described with reference to figures 1 to 3, figure 4 or figure 5 of the accompanying drawings.