GB2205997A

GB2205997A - Mounting circuit breakers on rails

Info

Publication number: GB2205997A
Application number: GB08711793A
Authority: GB
Inventors: Peter William Bowen; Bruce William Pickett
Original assignee: Crabtree Electrical Industries Ltd
Current assignee: Crabtree Electrical Industries Ltd
Priority date: 1987-05-19
Filing date: 1987-05-19
Publication date: 1988-12-21
Anticipated expiration: 2007-05-19
Also published as: HK6492A; SG59091G; GB8711793D0; GB2205997B

Abstract

A circuit breaker comprises a body (4) having a mounting recess (6) on the underside thereof, a fixed retaining formation extending into the recess on one side, and a retractable retaining element (12) extending into the recess on the other side 7. The retaining element (12) may be moved to its retracted position against the action of a spring (27), in which position it can be held, the retracted position being such as to enable translational movement of the circuit breaker relative to a mounting rail (40), to permit the circuit breaker to be disconnected from a bus bar. The retaining element (12) may be removed from the circuit breaker, to permit the circuit breaker to be used in circumstances where the mounting rail does not comprise an outwardly turned flange. <IMAGE>

Description

Title: "lmprovements relating to circuit breakers" Description of Invention This invention is concerned with improvements relating to circuit breakers.

A conventional circuit breaker, hereinafter referred to as being of the kind specified, comprises a body provided on an underside thereof with a mounting recess bounded at one side edge portion by an inwardly-turned lip, providing a fixed retaining formation having a re-entrant surface, an opposite side edge portions of the recess being bounded by straight side edges. The circuit breaker comprises a catch assembly, resiliently urged from a retracted position to an advanced position, in which advanced position a retaining element of the catch assembly projects a short distance into the recess.In such a circuit breaker, the retaining element may be on the same side of a medial plane of the circuit breaker as the bus bar by which the circuit breaker is connected to a supply of electricity, in which case the fixed re-entrance surface wiil be on the same side of the medial plane as the connector by which external wiring is connected thereto.

Conventionally circuit breakers of the kind specified are mounted on a mounting rail conventionally termed a "din-rail", which comprises parallel upwardly-facing flanges provided with narrow out-turned lips. The retaining formation is engaged beneath one of the lips with the underside of the circuit breaker inclined relative to the rail, and the circuit breaker is moved angularly so as to cause the retaining element to engage the other lip, the profile of the retaining element causing it to be momentarily depressed against the resilient force urging it to its advanced position, as it passes behind the other lip. The circuit breaker is then clamped to a conventional bus bar, supported in parallel relationship to the rail.

When it is required to remove one circuit breaker from an array of circuit breakers from the rail, the retaining element is manually retracted, and held retracted, and the circuit breaker is tilted to permit rectilinear movement of the circuit breaker relative to the rail to disengage the fixed retaining formation from the rail. This necessitates a temporary removal of the bus bar, and this is inconvenient since it involves disruption of the connections of other circuit breakers and/or of the isolator with the bus bar.

According to this invention there is provided, in combination, a circuit breaker of the kind specified and a mounting rail for the circuii breaker, the recess of the circuit breaker being of sufficient a size and the retaining element being capable of being aetracted a sufficient distance so as to enable, when the retaining element is in its retracted position, translational movement of the circuit breaker in the direction from the retaining element to the fixed retaining formation prior to removal of the circuit breaker from the mounting rail.

Thus where the recess is in the order of 35 to 36 mm (giving clearance over a 35 mm wide mounting rail) desirably the retaining element when in its retracted position permits translational movement in the order of I to 5 mm whilst maintaining the retaining element clear of the din-rail in readiness for movement of the circuit breaker from the mounting rail.

Preferably the catch assembly comprises means engagable with the body of the circuit breaker to restrain the retaining element against movement from its retracted position. Thus advantageously the retaining element is provided with a formation cooperable with a formation on the body of the circuit breaker to retain the retaining element in its retracted position.

For example the formation on the retaining element may be a recess, and the formation on the body of the circuit breaker may be a projection.

Preferably movement of the formation on the retaining element into engagement with the formation on the body involves resilient deformation of part of the retaining element, and conveniently such resilient deformation is effected in consequence of movement of the retaining element to its retracted position.

According to this invention there is also provided a circuit breaker of the kind specified comprising means which is operative on movement of the retaining element to its retracted position releasably to retain the retaining element against movement to its advanced position.

In this manner on removing a circuit breaker from a mounting rail, movement of the retaining element to its retracted position may be effected as a first step, and further effort to retain the retaining element in its retracted position whilst carrying out further steps in the dismounting operation is not needed.

Advantageously movement of the retaining element from its advanced to its retracted is sufficient in relation to the mounting rail upon which it is to be mounted, as to allow a sufficient translational movement of the circuit breaker to permit the circuit breaker to be separated at least from a bus bar prior to movement of the circuit breaker from the mounting rail.

Such a construction is particularly desirable where the retaining element is provided on the same side of the medial plane as the bus bar, and in which said translational movement is effective to allow the circuit breaker to be separated from the bus bar a distance sufficient to permit rotational movement of the circuit breaker.

Preferably in a circuit breaker both of the kind set out in the last preceding paragraph but three and in the last preceding paragraph but eight, the retaining element is also movable to an intermediate position between said advanced and retracted positions, and desirably the retaining element is spring-urged from its intermediate position to its advanced position.

According to this invention there is also provided a circuit breaker of the kind specified comprising a housing extending from a lower part of the body, said housing being provided with an aperture, the retaining element being positionable within the aperture, means being provided releasably to retain the movable element in the aperture.

In this manner when the circuit breaker is to be used in circumstances where securement of the circuit breaker on both sides of the mounting rail is desirable, the retaining element may be utilised in a conventional manner.

However where the circuit breaker is to be used in circumstances where securement to both sides of the mounting rail is not necessary, the retaining element may be removed from the aperture allowing the circuit breaker to be mounted on the mounting rail, without using the retaining element.

Advantageously the retaining element comprises a head portion and a tail portion extending from the head portion, the head portion when the retaining element is mounted on the housing being resiliently urged from a retracted to an advanced position in which it is adapted to engage beneath the lip of a mounting rail, such movement of the head portion conveniently being limited by engagement of part of the tail with one or more formations on the housing.

Preferably disengagement to permit the retaining element to be removed from the housing, or to be moved beyond its retracted position, may be effected by deformation of the tail from engagement with the formation or formations of the housing.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a circuit breaker which is a preferred embodiment of this invention, having been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings: FIGURE I is a side elevation of the circuit breaker which is the preferred embodiment of the invention; FIGURE 2 is an enlarged view of part of the circuit breaker, showing a catch assembly in an advanced position; FIGURE 3 is a view corresponding to Figure 2 showing the catch assembly in an intermediate position; and FIGURE 4 is a view corresponding to Figure 2 showing the catch assembly in a retracted position.

The circuit breaker which is the preferred embodiment of this invention is specifically of the kind specified, comprising a body 4 provided on an underside thereof with a mounting recess 6 bounded at one side edge portion by an inwardly-turned lip 8, providing a fixed retaining formation having a reentrant surface. On the opposite side edge of the recess is bounded by a straight side edge 7, and the circuit breaker comprises on said opposite side a catch assembly 10 comprising a retaining element 12 urged by spring means to an advanced position, in which it projects a short distance into the recess.

In the preferred embodiment the retaining element 12 is on the same side of a medial plane of the circuit breaker as of the connection 16 for a bus bar, the connection 18 by which external wiring may be connected to the circuit being on the opposite side of said medial plane.

Said one side edge 7 bounding the recess 6 is provided by a housing 20 extending downwardly from the body for on said one side, the housing being provided with an aperture 22. The catch assembly 10 comprises a head portion 24, a forward portion of said head providing said retaining element 12, and a tail 26 extending rewardly from the head, said tail 26 extending through the aperture 22.

In its normal operative position, a formation 28 provided on the rear face of the body 6 is located in a first aperture 30 provided in the tail, one face 30a bounding said aperture being a straight edge, the opposing edge 30b being inclined.

A spring 27 is operative between the housing and the head 24 to urge the head 24 to the left (Figure 4) and the retaining element into its advanced position, defined by an abutment of the formation 28 with the straight edge 30a of the recess 30. In this position the retaining element may be moved against the action of the spring 27 to an intermediate position (shown in Figure 2) in which the formation 28 engages the sloping face 30b of the recess 30.

The circuit breaker which is the preferred embodiment of this invention is suitable for use in conjunction with a mounting rail 40 comprising a base portion, parallel, upwardly-turned flanges, and outwardly turned lips 44 terminating in edges 46, such a mounting rail conventionally being termed a "din-rail". A typical din-rail has a width (distanced between the outside edges 46) of 35 mm, and in the preferred embodiment the width of the recess 6, measured in the absence of the fixed retaining formation and the retaining element 12, is in the order of 38 mm, this being the 35 mm width of the dinrail, plus the distance X as seen in Figure 4.

With the catch assembly in the position shown in Figure 2, the fixed mounting formation 8 may be hooked beneath the lip on one side of the mounting rail 40, and, by virtue of the sloping face of the retaining element 12, the spring 21 may momentarily be compressed to allow the head to pass beneath the said other lip 44 into the position shown in Figure 2.

By insertion of a tool such as a screwdriver 34 (Figure 2) into the aperture 30, the tail may be moved rewardly beyond the position shown in Figure 3, engagement between a sloping face 29 of the formation 28 with the sloping face 30b causing the tail to be deflected downwardly, and the formation 28 to pass into a second recess 36, in which position the retaining element is held against the action of the spring 27, this position being referred as the retracted position, shown in Figure 4.In this position the connecting screw 16 may be loosened and the separative distance X between the outer edge 46 of the flange 44 of the mounting rail 40 and the leading edge portion of the retaining element is sufficient to allow translational movement of the circuit breaker as a whole in the direction of the arrow B (Figure 1) a sufficient extent to enable the circuit breaker to be at least partially separated from the bus bar connected to the connecting element 16.

At this point the fixed retaining formation 8 is also clear of the opposite side edge of the mounting rail 40, allowing the circuit breaker to be lifted away from the mounting rail. The circuit breaker may then be rotated in the direction C, the side edge 7 following the edge of the din-rail, to complete separation of the circuit breaker from the din-rail.

Thus by the capability of moving the retaining formation 24 into a position further retracted than the normal (intermediate) position, a circuit breaker may be removed from an assembly of circuit breakers on a mounting rail without disturbance either to the bus bar or to other circuit breakers on the mounting rail. In addition the facility for holding the retaining element in its fully retracted position permits a single initial operative movement to be effected to so move the retaining element, without any subsequent operative movement, allowing the electrican to freely to positionally manipulate the circuit breaker.

Subsequently on return of the circuit breaker to the mounting rail, the tail 26 may be depressed a small distance to allow the formation 28 to return to the aperture 30, for normal operation of the circuit breaker.

In addition when it is desired to utilise the circuit breaker in conjunction with a mounting rail having no flange corresponding to the flange 44, by deformation of the tail 26 the formation 28 may be moved out of the aperture 30, and by simple linear movement the catch assembly may be removed from the housing 20.

Thus whilst the circuit breaker may be provided complete with a catch assembly of the kind above described, for use in operations where such a catch assembly is necessary, the catch assembly may be removed and disgarded for operations where its use is not required.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

I. In combination, a circuit breaker of the kind specified and a mounting rail for the circuit breaker, the recess of the circuit breaker being of sufficient a size and the retaining element being capable of being retracted a sufficient distance so as to enable, when the retaining element is in its retracted position, translational movement of the circuit breaker in the direction from the retaining element to the fixed retaining formation prior to removal of the circuit breaker from the mounting rail.

2. The combination according to Claim I wherein the size of the recess is such that with the retaining element in its retracted position translational movement of the circuit breaker a distance between í and 5 mm is permitted, preferably between 2 and 3 mm.

3. The combination according to one of Claims I and 2 wherein the catch assembly comprises means engagable with the body of the circuit breaker to retain the retaining element against movement from its retracted position.

5. The combination according to Claim 4 wherein the retaining element is provided with a formation cooperable with a formation on the body of the circuit breaker to retain the retaining element in its retracted position.

6. The combination according to Claim 5 wherein the formation on the retaining element is a recess, and the formation on the body of the circuit breaker is a projection.

7. The combination according to one of Claims 5 and 6 wherein movement of the formation on the retaining element into engagement with the formation on the body involves resilient deformation of part of the retaining element.

8. The combination according to Claim 7 wherein such resilient deformation is effected in consequence of movement of the retaining element to its retracted position.

9. A circuit breaker of the kind specified comprising means which is operative on movement of the retaining element to its retrocted position releasably to retain the retaining element against movement to its advanced position.

10. A circuit breaker according to Claim 9 wherein movement of the retaining element from its advanced to its retracted is sufficient in relation to the mounting rail upon which it is to be mounted, as to allow a sufficient translational movement of the circuit breaker to permit the circuit breaker to be separated a short distance at least from a bus bar prior to movement of the circuit breaker from the mounting rail.

II. A circuit breaker according to one of Claims 9 and 10 wherein the retaining element is provided on the same side of the medial plane as the bus bar, and said translational movement is effective to allow the circuit breaker to be separated from the bus bar a distance sufficient to permit rotational movement of the circuit breaker.

12. The invention according to any one of the preceding claims wherein the retaining element is also movable to an intermediate position between said advanced and retracted positions.

13. The invention according to Claim 12 wherein the retaining element is spring-urged from its intermediate position to its advanced position.

14. A circuit breaker of the kind specified comprising a housing extending from a lower part of the body, said housing being provided with an aperture, the retaining element being positionable within the aperture, means being provided releasably to retain the movable element in the aperture.

15. A circuit breaker according to Claim 14 wherein the retaining element comprises a head portion and a tail portion extending from the head portion, the head portion when the retaining element is mounted on the housing being resiliently urged from a retracted to an advanced position in which it is adapted to engage beneath the lip of a mounting rail.

16. A circuit breaker according to Claim 15 wherein such movement of the head portion is limited by engagement of part of the tail with one or more formations on the housing.

17. A circuit breaker according to any one of Claims 14, 15 and 16 wherein disengagement to permit the retaining element to be removed from the housing, or to be moved beyond its retracted position, may be effected by deformation of the tail from engagement with the formation or formations of the housing.

18. A circuit breaker constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

19. In combination, a circuit breaker of the kind specified and a mounting rail for the circuit breaker, constructed and arranged substantially as herebefore described with reference to the accompanying drawings.

20. Any novel feature or novel combination of features hereinbefore described and/or as shown in the accompanying drawings.