GB2208454A

GB2208454A - Electric switch locking device

Info

Publication number: GB2208454A
Application number: GB8818427A
Authority: GB
Inventors: Mark Francis Smith
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1987-08-05
Filing date: 1988-08-03
Publication date: 1989-03-30
Also published as: GB8718487D0; GB8818427D0

Abstract

A simple and inexpensive locking device for the dolly 2 of a miniature electric circuit breaker 1 or other electric switch comprises a locking member 11 which has a first region 23 for engaging the dolly and a second region 21 for engaging a surface 3 of the switch and a guide member 15 on which the locking member is slidably mounted and which is so attached to the switch that the second region 21 of the locking member engages the surface of the switch. The locking member 11 is slidable with respect to the guide member 15 between a first position in which the first region 23 of the locking member engages the dolly 2 and a second position in which the first region 23 of the locking member is so spaced from the dolly that the dolly can be manually operated. Retaining means such as a padlock 27 or snap action means acts between the locking member 11 and the guide member 15 to retain the locking member in the first position to prevent operation of the dolly. The guide means 15 is a wire loop whose ends engage aperture 5 or 6 of the switch to respectively lock the dolly in opposite positions. <IMAGE>

Description

ELECTRIC SWITCH LOCKING DEVICE This invention relates to a locking device for an electric switch, isolator or any other electric apparatus having a dolly for manual operation, all such electric apparatus, for convenience, hereinafter being included in the generic expression "electric switch", which locking device can be used to retain the dolly of an electric switch in either its "on" position or its "off" position. The invention is especially, but not exclusively, concerned with a locking device suitable for an electric switch in the form of a miniature circuit breaker.

It is an object of the present invention to provide, for use with an electric switch having a dolly for manual operation, an improved locking device which is simple in form and inexpensive to manufacture.

Acdording to the invention, the improved locking device comprises a locking member which has a first face for engaging the dolly and a second face for engaging a surface of the switch; a guide member on which the locking member is slidably mounted and which is adapted to be so attached to the switch that said second face of the locking member engages said surface of the switch, the locking member being slidable with respect to the guide member between a first position in which said first face of the locking member engages the dolly and a second position in which said first face of the locking member is so spaced from the dolly that the dolly can be manually operated; and retaining means adapted to act between the locking member and the guide member to retain the locking member in said first position to prevent operation of the dolly.

Preferably, the retaining means is separately formed with respect to the locking member and in a preferred embodiment is a padlock. In this case, preferably the locking member has a hole through which the hasp of the padlock can pass, the hole being so located relative to the guide member when the locking member is in said first position that the hasp of the padlock prevents relative sliding movement between the locking member and the guide member.

Additionally, or alternatively, the locking member may have integral with the member at least one shoulder against which the guide member abuts when the locking member is in said first position and which resists ready sliding movement of the locking member with respect to the guide member towards said second position.

Preferably, the guide member is a length of resilient wire which is folded approximately into the shape of a U, the U-shaped length of resilient wire itself being folded transversely of its length intermediate of its rounded and open ends to approximately Shape, the arrangement being such that the free ends of the resilient U-shaped guide member are adapted to engage in holes in the body of the switch and the locking member is constrained to slide with respect to and between the limbs of the resilient U-shaped guide member by opposed surfaces on the locking member which overlie and underlie parts of the limbs of the guide member nearer its open end.Preferably, also, the locking member has abutments against which parts of the limbs of the resilient U-shaped guide member nearer its rounded end will bear when the locking member is in said first position so that the locking member and guide member cannot be readily separated one from the other.

Where the guide member is a U-shaped length of resilient wire folded transversely of its length intermediate of its rounded and open ends to approximately L-shape, the additional, or alternative, retaining means may comprise a shoulder on each of two opposite side walls of the locking member, the shoulders being of such a shape that parts of the limbs of the will resilient U-shaped guide member nearer its rounded end will make snap fits behind the shoulders as the locking member is caused to slide towards said first position.

The invention is further illustrated by a description, by way of example, of a preferred locking device for use with a miniature electric circuit breaker with reference to the accompanying drawings, in which: Figure 1 is a fragmental general assembly, drawn on an enlarged scale, of a miniature electric circuit breaker with the preferred locking device locking the dolly of the breaker in the "off" position; and Figures 2 and 3, respectively, are isometric and side views of the improved locking device.

Referring to the drawings, a miniature electric circuit breaker 1 has in a front face 3 a hole through which protrudes a dolly 2. Upstanding from the front face 3 of the circuit breaker 1 on opposite sides of the dolly 2 are two lugs 4 which have two pairs of aligned holes 5 and 6 on opposite sides of the pivotal axis of the dolly.

The preferred locking device 10 comprises a locking member 11 and a guide member 15 on which the locking member is slidably mounted. The locking member 11 comprises a moulded body of plastics material having a base 21 which protrudes beyond the side walls of the member and, at one end of the moulded body, a face plate 23 which protrudes beyond the side walls of the member.

The face plate 23 of the locking member 11 has two planar surfaces which are inclined at an obtuse angle to one another, one surface 12 of these two surfaces constituting a face for engaging the dolly 2 of the circuit breaker 1. The other surface 24 of the face plate 23 of the locking member 11 and the exposed upper surfaces 22 of the base 21 constitute opposed surfaces by means of which the locking member is constrained to slide with respect to the guide member 15. The undersurface 13 of the base 21 is of planar form and constitutes the second face of the locking member 1l for engaging the.front face 3 of the circuit breaker.

The guide member 15 is a length of resilient wire which is folded approximately into the shape of a U, the U-shaped length of resilient wire itself being folded transversely of its length intermediate of its rounded end 18 and its open end to approximately L-shape. The longer limbs 17 of the U-shaped length of resilient wire constitute the parts of the guide member 15 on which the locking member 11 is constrained to slide by means of its opposed surfaces 22 and 24 which underlie and overlie the longer limbs. At the open end of the U-shaped length of resilient wire, the free ends 20 of the length of wire are folded transversely outwardly and are adapted to engage in one of the two pairs of aligned holes 5 and 6 in the lugs 4 upstanding from the face 3 of the circuit breaker 1.When, as shown, the transversely extending parts 20 of the resilient U-shaped guide member 15 engage in the aligned holes 5 in the lugs 4 of the circuit breaker 1, the locking member 11 is slidably mounted with respect to and between the limbs 17 of the guide member between a first position in which the face 12 of the locking member engages the dolly 2 and a second position in which the face 12 of the locking member is so spaced from the dolly that the dolly can be manually operated. When the locking member 11 is in said first position with the surface 12 engaging the dolly 2, the shorter limbs 18 of the resilient U-shaped guide member 15 bear against abutments 25 integral with the locking member 11 at the end of the member remote from the face plate 23, so that the locking member and guide member cannot be readily separated one from the other.

Spaced a short distance from the abutments 25 and extending transversely through the body of the locking member 11 is a hole 26 through which the hasp 28 of a padlock 27 can pass to lock the locking member with respect to the guide member 15 in said first position when the surface 12 is abutting the dolly 2, which is in the "off" position, and the shorter limbs 18 of the guide member bear against the abutments 25.

The end walls 29 of the face plate 23 remote from the surface 12 limit the extent to which the locking member 11 can slide with respect to the guide member 15 towards said second position.

The preferred locking device 10 can also be employed for locking the dolly 2 in the "on" position by removing the device from its illustrated position on the circuit breaker 1 and engaging the transversely extending parts 20 of the resilient U-shaped guide member 15 in the aligned holes 6 in the lugs 4 of the circuit breaker.

Claims

Claims:

1. For use with an electric switch having a dolly for manual operation, a locking device comprising a locking member which has a first face for engaging the dolly and a second face for engaging a surface of the switch; a guide member on which the locking member is slidably mounted and which is adapted to be so attached to the switch that said second face of the locking member engages said surface of the switch, the locking member being slidable with respect to the guide memberbetween a first position in which said first face of the locking member engages the dolly and a second position in which said first face of the locking member is so spaced from the dolly that the dolly can be manually operated; and retaining means adapted to act between the locking member and the guide member to retain the locking member in said first position to prevent operation of the dolly.

2. A locking device as claimed in Claim 1, wherein the retaining means is separately formed with respect to the locking member.

3. A locking device as claimed in Claim 2, wherein the retaining means is a padlock.

4. A locking device as claimed in Claim 3, wherein the locking member has a hole through which the hasp of the padlock can pass, the hole being so located relative to the guide member when the locking member is in said first position that the hasp of the padlock prevents relative sliding movement between the locking member and the guide member.

5. A locking device as claimed in any one of the preceding Claims, wherein the locking member has integral with the member at least one shoulder against which the guide member abuts when the locking member is in said first position and which resists ready sliding movement of the locking member with respect to the guide member towards said second position.

6. A locking device as claimed in any one of the preceding Claims, wherein the guide member is a length of resilient wire which is folded approximately into the shape of a U, the U-shaped length of resilient wire itself being folded transversely of its length intermediate of its rounded and open ends to approximately L-shape, the arrangement being such that the free ends of the resilient U-shaped guide member are adapted to engage in holes in the body of the switch and the locking member is constrained to slide with respect to and between the limbs of the resilient U-shaped guide member by opposed surfaces on the locking member which overlie and underlie parts of the limbs of the guide member nearer its open end.

7. A locking device as claimed in Claim 6, wherein the locking member has abutments against which parts of the limbs of the resilient U-shaped guide member nearer its rounded end will bear when the locking member is in said first position so that the locking member and guide member cannot be readily separated one from the other.

8. A locking device as claimed in Claim 6 or 7, wherein shoulders on two opposite side walls of the locking member are of such a shape that parts of the limbs of the resilient U-shaped guide member nearer its rounded end-will make snap fits behind the shoulders as the locking member is caused to slide towards said first position.

9. For use with a miniature electric circuit breaker having a dolly for manual operation, a locking device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.