GB2064225A

GB2064225A - Mounting assembly for electrical devices

Info

Publication number: GB2064225A
Application number: GB8037799A
Authority: GB
Original assignee: Midland Electric Manufacturing Co Ltd
Current assignee: Midland Electric Manufacturing Co Ltd
Priority date: 1979-11-26
Filing date: 1980-11-25
Publication date: 1981-06-10
Also published as: GB2064225B

Abstract

A mounting assembly for electrical devices designed for DIN-rail mounting consists of a mounting plate (12) formed with a strip (23) lying in the plane of the plate and having a free edge (28) lying parallel to a bus- bar or bus-bars (25). Each electrical device such as a miniature circuit- breaker 16 is held in place by having its catch 18 engage behind the edge (28) and by the attachment of its terminal (16B) in a slot (27) of the bus-bar (25). The plate (12) is cut away, as by the formation of the slot (22), below the foot (19B) of electrical device (16). <IMAGE>

Description

SPECIFICATION Mounting assembly for electrical devices This invention relates to a mounting assembly for electrical devices each of the type having a mounting face formed with a shallow U-shaped recess between two feet; the recess is adapted to receive a rail of the type described in German Standard DIN 46277 Sheet 3. The electrical device has catch means projecting into the recess to engage with an edge of the DIN-rail and electrical connection means at opposite ends. An example of such an electrical device, which will be referred to hereinafter as "an electrical device of the type described" is a miniature circuit breaker (MCB).

It is frequently necessary to mount a number of such electrical devices together for connection to a common bus-bar, in the case of a single-phase supply, or to a number of bus-bars, in the case of a polyphase supply. Thus, in a domestic distribution system, it is known to clip a number of MCB's to a DIN rail and thereafter to connect them to a busbar or bus-bars. In this known arrangement, the bus-bar or bars can be connected only when all the MCB's are in place on the DIN rail and, in order to remove one of the MCB's it is necessary first to disconnect and dismantle the bus-bar or bars.

In British patent specifications Nos. 1,554,614 and 2,007,434A alternatives to the conventional DlN-rail have been proposed. In each the electrical device is secured by the engagement of the catch behind a single elevated catch plate and by the attachment of the connection means to the busbar. Then any electrical device can be secured in place or removed without disturbing other such devices already in situ.

In particular, the arrangements described and illustrated in specification No. 1,544,614 entail the use of a catch plate spaced above a back plate and formed by upsetting a part of the back plate or attachment of a separate catch plate to the back plate. In addition, the specification requires the electrical device to have a portion which engages between the back plate and the bus-bar. The arrangement of specification No. 2,007,434A on the other hand merely uses a modified form of Dl N-rail with one flange removed.

The present invention provides a mounting assembly for a plurality of electrical devices of the type described, the assembly comprising: a mounting plate which includes in the plane of the plate an elongate mounting strip having a width such that the strip can be accommodated in the recess of each said electrical device to be mounted, the strip having a free edge for engagement with the catch of each such electrical device; and at least one bus-bar spaced from the strip on the side thereof distant from said edge and located substantially parallel to said edge, and provided with attachment means for the connection means of each such electrical device, whereby each said device is independently securable jointly by engagement of its catch with said edge and by engagement ot its connecton means with the attachment means of the bus-bar or one of its bus-bars, the plate being such that that foot of each said device which in use is adjacent the bus-bar or bus-bars is unrestricted by the plate. Leaving that foot unrestricted allows the foot adjacent to the bus-bar or bus-bars to project beyond the plane of the plate. Further, the fitting and removal of the electrical device renders the mounting assembly more flexible in its use.

The invention will be more readily understood by way of example, reference being made to the accompanying drawing, in which Figures 1, 2 and 3 are perspective views of alternative forms of mounting assembly for a number of MCBs or like electrical devices, each showing one MCB mounted thereon, Figure 4 is a perspective view of a mounting assembly for two banks of electrical devices; Figure 5 is a section on the line V-V of Figure 4, showing the mounting of MCB's on the assembly, and Figure 6 illustrates a modification of Figure 4.

The mounting means shown in Figure 1 consists of a rectangular mounting plate 12, two parallel edges of which are bent outwardly through substantially 900 to form support flanges 13. Portions of a pair of parallel side edges are cranked to form narrow strips 14 spaced from the plate 12 and provided with mounting holes 1 5 by which the mounting plate may be secured to a suitable surface with screws or like attachment devices.

A typical MCB 1 6 is shown in Figure 1. The MCB has a shallow U-shaped recess 1 7 in its mounting face, that recess being adapted to receive a Dl N-rail, although in the present arrangement such a rail is not used. On each side of the recess 17, there is a foot 1 9A or 19B. A spring-loaded catch 1 8 is carried by the structure of the MCB and is biased into the recess 1 7 as shown; it may be withdrawn against the springloading by operation of a connected finger 20. At opposite ends the MCB 1 6 has an electrical connection means in the form of a screw 1 6A or 16B.

Reverting to the mounting plate 12, it has two parallel rectangular slots 21 and 22 which are separated by a strip 23 of the mounting plate, that strip lying the plane of the plate. The strip 23 is narrower than the recess 1 7. The material of the mounting plate may be bent away from the plane of the plate along the edge of strip 23 bordering the slot 22, as shown at 24, in order to give added support to the mounting plate and strength to strip 23.

A bus-bar 25 is located on the mounting plate by one or more pillars 26. In the arrangement shown a pair of pillars are located at opposite ends of the slot 22. The bus-bar 25 is spaced from, and is parallel to, the plane of the mounting plate 12 and overlies that part of the slot 22 more distant from the slot 21. The bus-bar itself is slotted at intervals along its length with the slots 27 opening to the edge nearer the strip 23. The bus-bar slots are spaced from one another by the width of the MCBs.

In order to mount an MCB on the mounting plate, its bus-bar connection screw 1 6B is loosened and the MCB is placed on the strip 23 and moved on that strip to engage its screw 1 6B in a slot 27 of the bus-bar 25. The foot 1 9A of the MCB projects into the slot 21. When the screw is properly positioned in its bus-bar slot, the edge 28 of the strip 23 which is more distant from the busbar is engaged by the catch 1 8 as shown in Figure 2. When the screw is tightened, the MCB is securely held by the bus-bar and by the engagement of the catch 1 8 with the edge 28.

The width of slot 21 is such that the foot 1 9A of the MCB is a close fit in it. This has the virtue of accurately locating the MCB in relation to the busbar and requires that the spring loaded catch 1 8 must be released to free an MCB from the mounting assembly.

The foot 1 9B adjacent the bus-bar 25 is unrestricted by the mounting plate 12 by virtue of the slot 22 into which the foot projects. It is important that foot 1 9B should be so unrestricted because, as catch 1 8 engages edge 28 of plate 12 and strip 23 is received in recess 17, foot 1 9B is below the level of plate 12. Also, the provision of a slot 22 facilitates the fitting of the connection screw 1 6B in the attachment means formed by slot 27.

Other MCBs or other like devices may be simlarly secured in place without disturbing those devices already in position. Similarly, any device may be removed from the mounting plate without requiring the prior disassembly of the bus-bar 25.

A single bus-bar 25 is used as shown when the electrical supply is single phase, but for a polyphase supply, a number of bus-bars are provided for appropriate connection of the MCBs.

In practice, the mounting plate and the electrical devices carried thereby can be located in an enclosure The mounting assembly of Figure 2 is generally similar to that of Figure 1 and its operation is the same. It differs from Figure 1 primarily in that part of the mounting plate 12 adjacent to the bus-bar 25 is cut away, dispensing with that part of the plate which in Figure 1 lies adjacent the bus-bar and causing the disappearance of the slot 22.

Strip 23 is now bounded on one side by an outer edge 30 of the plate 12. As in Figure 1, the foot 1 9B of each MCB 1 6 or other electrical device is free of restriction by the plate 12, enabling the MCB foot adjacent bus-bar 27 to project below the level of plate 12.

Figure 2 further shows a DIN rail 31 which is integral with the plate 12 an on which one or more isolators or other Dl N-mounted devices (not shown) may be mounted in conventional manner.

The mounting assembly is fixed in position by screws inserted through holes 32 in the DIN rail 31.

The mounting assembly of Figure 1 is also closely similar to that of Figure 1, and differs therefrom only in the absence of that part of the mounting plate 12 which, in Figure 1, is on the side of strip 23 distant from bus-bar 25; in other words, the edge of the plate coincides with the edge 28 of strip 25. In Figure 3, the foot 1 9A is no ionger closely confined and is no longer registered in position relative to the bus-bar 25 by the width dimension of slot 21. To ensure that the MCB 1 6 is properly held in the correct position relative to the bus-bar, the latter has key-hole slots 35 rather than the parallel-sided slots 27 of Figure 1.The screw 1 6B has a lengthened chamfer to engage with the head of a slot 35, so that when the screw is tightened it is centralised in the slot head and is prevented from moving out of the slot.

Figures 4 and 5 illustrate a mounting plate 40 designed to mount two banks of MCBs or other electrical devices. The mounting plate 40 is effectively two of the plates 12 of Figure 1 arranged back-to-back, and corresponding reference numbers to those of Figure 1 are used in Figures 4 and 5 with the addition of "A" or "B".

Thus each half of the plate 40 has a pair of slots 21A, 24A or 21 B, 24B defining between them a strip 23A or 23B. In the centre of the plate, between the two slots 22A and 22B, there is an area of plate 41 to receive a T-shaped insulating structure 42 (Figure 5) containing bus-bars and, in the overhanging parts 43 of the structure, connections to connectors 1 6B of the MCBs. The mounting plate is fixed in place by screws or bolts passed through holes 44 in the plate 40; thus, Figure 5 shows bolts 45 attaching the mounting plate to a back plate 46.

The MCBs or other devices are mounted on the strips 23A and 23B as described in relation to Figure 1 and held in place as before by the catches 1 8 and the connector screws 1 6B (not shown), the width of the slots 21 A and 21 B registering the devices correctly in relation to the bus-barcontaining structure 42.

Figure 6 shows a modified two-bank mounting plate, which in each half is similar to the structure of Figure 3, in that the slots 28A, 28B are dispensed with and the catch engaging edges 28A and 28B are furnished by outer edges of the plate 40 itself. In this case, the connections between the MCBs and the bus-bars are of the key-hole slot type illustrated in Figure 3 to ensure registration.

Claims

1. A mounting assembly for a plurality of electrical devices of the type described, comprising: a mounting plate which includes in the plane of the plate an elongate mounting strip having a width such that the strip can be accommodated in the recess of each said electrical device to be mounted, the strip having a free edge for engagement with the catch of each such electrical device; and at least one bus-bar spaced from the strip on the side thereof distant from said edge and located substantially parallel to said edge, and provided with attachment means for the connection means of each such electrical device, whereby each said device is independently securable jointly by engagement of its catch with said edge and by engagement of its connection means with the attachment means of the bus-bar or one of its bus-bars, the plate being such that that foot of each said device which in use is adjacent the bus-bar or bus-bars is unrestricted by the plate.

2. A mounting assembly according to claim 1, in which the strip is formed between two parallel slots in the plate, one of the slots extending at least part way under the bus-bar to receive the adjacent foot of each electrical device when attached to the bus-bar.

3. A mounting assembly according to claim 2, in which the slot further from the bus-bar or busbars has a width such that the foot of the electrical device distant from the bus-bar or bus-bars is receivable in that slot and confined against significant movement relative to the plate.

4. A mounting assembly according to claim 1, in which the strip is formed between a slot in the plate and an outside edge of the plate, that edge being so located in relation to the bus-bar or busbars that the plate does not impede the foot of the electrical device adjacent the bus-bar or bus-bars.

5. A mounting assembly according to claim 4, in which the slot has a width such that the foot of the electrical device distant from the bus-bar or bus-bars is receivable in that slot and confined against significant movement relative to the plate.

6. A mounting assembly according to claim 1, in which the strip is formed between a slot in the plate and an outside edge of the plate, the slot extending at least part-way under the bus-bar or bus-bars to receive the adjacent foot of each electrical device when attached to the bus-bar, and that outside plate edge forming said free edge engaged by the catch of each electrical device.

7. A mounting assembly according to any one of claims 1 to 3 and 6, in which the plate is adapted to mount two parallel banks of electrical devices, having for that purpose two said parallel strips for supporting the devices of the respective banks.

8. A mounting assembly according to claim 7, in which a structure containing the bus-bar or busbars is mounted centrally on the mounting plate between the location of the two banks.

9. A mounting assembly for a plurality of electrical devices of the type described, substantially as herein described with reference to the accompanying drawings.