GB2151406A - Electrical accessories - Google Patents

Abstract

A switched electrical accessory has an operator (16) for its normal contacts (12) and a further contacts 20 made and broken by a switch member (22) according to whether or not its associated latch (28) engages another member (36). The member (36) and the switch member (22) have opposing relatively strong and weak biasing springs (38 and 24), respectively to assure their separation and break action of the switch member (22) at latch disengagement. Re-engagement of the latch (28) is by movement of the member (36) first against its bias (38) to pick up the switch member (22) and then by its bias (38) to overcome the other bias (24). That re-engagement movement is by operation of the operator (16) beyond its normal ON position. Tripping of the latch 28 by a circuit condition sensor coil releases contacts 20 to be opened by springs 24 and also releases member 36 which is then driven by the spring 38 to act on the operator 16 to open the contacts 12. <IMAGE>

Description

SPECIFICATION Electrical accessories The invention relates to switched electrical accessories and to additional switching provision therein for operation in conjunction with another facility, usually, if not necessarily, earth leakage circuit breaking; but some aspects of the invention have application more generally to electrical accessories.

The use of earth leakage circuit breakers is not new, but it is increasing, and likely to continue to do so in relation to particular load appliances or load circuits, for example operative or feeding out-of-doors or into rooms with water supplies or to be washed out frequently.

Accordingly, attention has been directed to developing mains switches and/or socket-type electrical accessories with incorporated earth leakage breaker provision to provide smaller and less cumbersome products compared with separate units wired in between a switch and an appliance, or as a large plug-in unit, or as a separate provision to a circuit. Preferred units fit to a standard accessory fixing box.

Aspects of this invention contribute in that respect, One aspect is for a switched electrical accessory to have its normal switch operator, usually a dolly or rocker, interlocked with operation of further contacts that are operated in response to means other than said normal switch and restored by operation of said normal switch. It is further preferred that the interlock breaks the normal switch contacts when said further contacts are broken.

In preferred embodiments, an electrical accessory has two sets of contacts in at least its "live" side, one set being associated, for making and breaking functionally in normal manner, with the usual accessory switch, and the other set being connected in series with the first set and associated with means for breaking independently of the usual accessory switch, but then also moving the latter to its break position. It is also preferred that normal making and breaking of said one set of contacts by the usual accessory switch operator shall not at all affect the other set of contacts.

but that making or re-making of the latter shall be by extension of the normal make action of said usual accessory switch operator.

More specifically, a switch link associated with the other set of contacts will have two possible and is further associated with releasable latch means to hold it in one operative position (make) until the latch means is released, means then operative to ensure movement to the other operative position (break) and resisting recovery of the one position (make), and means operative temporarily to overcome the last-mentioned means and reset the latch means only on movement of the normal accessory switch other than usual make-and-break movement, usually simply beyond make movement.

In a particular embodiment, the switch link is subject to a first bias towards its break position which first bias always acts when the switch link is in its make position; a break forcing member for the usual accessory switch is subject to a second bias towards break action; latch means serves (usually directly) to interconnect the break forcing member and the switch link against both biases, the second bias then overcoming the first bias to maintain making of the other contacts by the switch link, until released by associated circuit condition sensing means (usually on earth leakage detection solenoid); and the latch means is subject to bias effective to reset the latch means when the break forcing member is moved against the second bias and the first bias towards a latch pick-up position relative to the switch link.

In practice, using helical coil compression springs, the switch link may move in a guide well by and against the first bias (for break and make of the other contacts, respectively); the break forcing member may move in or over a guide, say above the aforementioned guide well, by and against the second bias (for break of the first contacts via the usual accessory switch actuator and for resetting the latch means by extended movement of the usual accessory switch actuator, respectively); and a latch member may be attached to one of the switch links and the break forcing member (conveniently the former) to move by and against the third bias (for latching and release, respectively), say within the break forcing member or a guide therefor.

Other of the above-mentioned aspects concern the manner of operation of latching means in an electrical accessory with built-in abnormal circuit condition, typically earth leakage detection circuitry and associated switch means. First, is the use of two opposed spring biases, one for breaking with latch means released and the other stronger for making with latch means engaged and facilitating re-engagement by forcing against the second spring bias as well as the second spring bias, usually with preferred swinging latch means.

Also there is the employment of a latch member that serves in one position to hold said switch means in its ON condition and in another position to release that switch means to its OFF condition, the latch member swinging between its said position and being subject to a spring bias that both resists movement of the latch member to its said other position and forces achievement of said OFF condition of said switch means.

That is realisable where a movable switch member or switch link (of said switch means) is effectively controlled by the circuit condition detection circuitry via said latch member, the movable switch member or switch link being biased towards an OFF position by one spring means (which may be the aforesaid first bias) and towards an ON position by other spring means as said spring bias (and which may be the aforesaid second bias) that is stronger than and opposes said one spring means, and swinging of the latch member from its said one or latching position to its said other or non-latching position against bias from said one spring means.

Then, of course, said spring bias or other spring means of this second aspect of the invention serves, in effect, to provide both of the above-mentioned first and third biasses, and can concurrently achieve same by embodiment as a helical spring about an elongate part of said latch member. Moreover, the latch member may swing about its connection whether to the latch member or to a part movable to reset the movable switch member or switch link to said ON condition, which part may be the above-mentioned break forcing member.

At least those other aspects are, of course, applicable to unswitched accessories, such as plugs etc., and having a reset button instead of said break-forcing member, Practical implementation of this invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figures 1, 2 and 3 diagrammatically represent different operate states of a switched electrical accessory fitted with an earth leakage circuit breaker; Figures 4, 5, 6 and 7 show different operative positions for such an accessory relative to a specific rocker switch; Figure 8 shows a plan view of parts involved for Figures 4, 5, 6 and 7; Figures 9, 10, 11 and 1 2 show details of a specific earth leakage circuit breaker mechanism; and Figures 1 3 and 1 4 show diagrammatically, parts of mechanisms with alternative latching arrangements.

Referring first to Figures 1 to 3, switched electrical accessory 10, typically mains switch or even a British 1 3-amp ring-mains three-pin socket, has its usual switch indicated at 1 2 relative to live line 14 and operated by a rocker 16, normally in the front plate 1 8 of the accessory. In the same mains line 14 is another switch 20 for which make and break, i.e. ON and OFF conditions, are controlled by a switch link 22 that is shown spring-biassed at 24 towards break.

The switch link 22 is carried at 26 by a latch member 28 movable with the switch link on break and is shown spring-biassed at 30.

The latch member 28 has a latch 32, shown, at its free end, capable of engaging at 34 a break-forcing member 36 itself shown springbiassed at 38.

At least in the relevant direction, the bias 38 is opposed to but stronger than the bias 24 so that when the latch member 28 interconnects the switch link 22 and the breakforcing member 36 the former is forced to make the switch 20. The bias 30 is sufficient to locate the latch member 28 in a position for latching but will be overcome by operation of release member 38 driven by a circuit condition sensor 40, typically a coil (see Figure 2 only).

The break-forcing member 36 is shown below one end 42 of the rocker 1 6 (corresponding to "ON" for the accessory concerned) and is movable by its bias 38 to force the rocker 1 6 to its OFF position when switch link 22 also goes to break under the action of its bias 24.

At operation of the circuit condition sensor 40, the switch 20 will break and so will the usual accessory switch 12, see Figure 3. That condition will be preceded by an ON condition, see Figure 1, where the latch 32 is engaged. Resetting can be achieved only by extension of ON operation of the rocker 16, see Figure 2.

The system just described is readily implemented as a mechanism at or adjacent to the switch position of an electrical accessory.

Turning to Figures 4 to 7, switch position 40 of an electrical accessory is at and within a customary insulating housing 42 secured to plate 1 8 and having an interior chamber 44.

Switch actuating rocker 1 6 is operative,on a pivot 46, between normal ON and OFF positions (Figures 1 and 4, respectively) in customary manner in a slot 48 in the plate 1 8 and relative to limit ledges 50, 52 to control an over-centre switch element 54 and first contacts 56, 58.

At one end (down for ON) the rocker 1 6 is shown with a foot 60 that is directly above break-forcing member 36 movable up and down relative to a guide 62. In practice of course (and see below for Figure 8), guidance of the member 36 may simply be by cooperation with a cavity. The break-forcing member 36 is biassed (38) for upward movement relative to its guide 62 by helical compression spring means 64 (Figure 4). Interiorly, the break, forcing member 36 is associated with latch member 28 that is subjected to bias (30) via a helical compression spring 66 (Figures 5 to 7) seated on switch link 22 and extending about the latch member 28 to a collar thereon (not shown) so as to tend to maintain the latch member 28 upright relative to the switch link, which position corresponds to latching engagement of the member 36.

The switch link 22 carries the latch member 28 its one end and permits swinging or rocking movement of the latch member 28 restrained by the spring 66 and forced by the sensor coil 40 (not shown in Figures 4 to 7).

The switch link has contacts 70, 72 for making and breaking with fixed contacts 74, 76 depending on whether the switch link 22 is up or down in a guide well 78. The switch link 22 is biassed (24) downwards by helical compression spring means 80 acting between the link 22 snd the guide 62 (see Figure 4).

Figure 4 shows the rocker 1 6 in its ON position relative to the switch member 54 and the first contacts 56, 58. Also, the switch link 22 is heid upwards by latching of the latch member 28 in the break-forcing member 36 and by the fact that the spring means 62 is substantially stronger than that 80. This is a stable condition mechanically and the rocker 1 6 can be switched to the ON position and its OFF position without any disturbance of the switch link 22.

However, if that latching is released, see Figure 5, the switch link 22 will be forced downwards by the spring means 80, thereby breaking the contacts 70, 72 and 74, 76.

Moreover, see Figure 6, the break, forcing member 36 will be driven upwards by the spring means 64 with enough force to push the rocker 1 6 into its OFF position, thereby breaking the contacts 56, 58. Such movement of the member 36 is limited by ledging 82.

Such unlatching, usually by an earth leakage detector including the coil 40 (see Figures 1 to 3) will thus be effective to break the circuit through the accessory (at 70 72 and 74 76); further to break such circuit (at 56, 58);visually to demonstrate such by forcing the rocker 1 6 to its OFF position; to give further indication by resistance that will be felt to any movement of the rocker to its ON position; to maintain a broken circuit (70, 72 and 74, 76) even if the contacts 54, 56 are made by operation of the rocker 16; and to disallow any stable ON rest position for the rocker 16.

Provision for relatching is indicated in Figure 7 and relies upon what is effectively an extension of ON movement of the rocker 1 6 so that the member 36 is depressed sufficiently for latch member 28 to reengage therewith, whereafter the rocker can relax to the Figure 4 ON position and the member 36 will lift the switch link 22 to make contacts 70, 72 and 74, 76. Extended movement of the rocker 1 6 is permitted by reason of a degree of float allowed in the rocker pivot, see 84 in Figure 7, so that the rocker 1 6 can finally pivot about its end 86 in resetting the earth leakage circuit breaking facility.

Turning to Figure 8, a practical embodiment of a stiff metal switch link is shown at 11 6 with two side extensions 90, 92 having upturned engagers 94, 96 for two springs 80 (not shown). The switch link 11 6 is in a generally cruciform well 1 22 and the extensions flank corner pieces 98, 100 integral with two corners of one element of the well 1 22 and carrying seats 102, 104 for two springs 64 so that the springs 80 and 64 will be at opposite corners of a rectangle for stability. Upward movement of the link 11 6 is simply limited by fixed carriers 106, 108 for the contacts 74, 76. A connection from the carrier 108 is shown at 110 to an output terminal position 11 2 within an insulating well.Another insulating well is shown for the earth leakage unit/coil 40.

Turning to Figures 9 to 12, a preferred break-forcing member 1 36 has a clevis-like slide part 102 and an end part 1 04, the whole being movable in a guided manner in a suitable well 106 by springs 108, 110 at least at 112, 114, usually also at other corner positions, see rearwardly at 11 6 in Figure 9.

A latch member 1 28 and associated spring 1 66 run in a central cavity of the slide part 102 with curved retainers 118, 1 20 riding cam-fashion on side abutments 122, 1 24 of that central cavity in guiding the latch member 1 28 relative to the slide part 102 to and from latching engagement with retainer boss formations 1 26 (see Figures 10 and 11). A suitable interference fitting pin 1 30 will serve to seat the spring 166.

Turning to Figure 13, a latch member 228 is pivotted at 230 to a movable part 216 that may be a reset button or a break-forcing member with a function as described above for parts 36 and 1 36 and guided at 262 in an accessory part. A hooked end latch 232 of the latch member 228 engages under a ledge 234 in a slot 236 in a body 220 carrying a switch link 222 in a well 224 of a base part 242 of an electrical accessory and guided at slotting 226 above contacts shown made.

The latch member 228 has a cross-piece, ledge or flange 218 against which is seated a helical compression spring 244 also seating on the body 220 of the switch link 222, i.e.

so as to bias the latter towards break and also effectively to centre the latch member 228 and resist it swinging about its pivot 230 out of its make position to its break position (see dashed) where it clears the ledge 234.

A stronger helical compression spring 238, or each of two or more, acts between the accessory part 242 and the movable part 216.

The latch member 228 is made to swing from its make position to its break position by driven part 240A of an actuator 240, usually of earth leakage detection circuitry, and in an extension of the slot 236.

Figure 1 4 shows another system with, compared to Figure 13, its latching member 228' pivotted at 230' in a slot 250 in switch link body 230', its switch link release and latching member bias spring 244' acting between break-forcing or reset member 216' and abutment 218' on the latching member 228', and latch end 232' of the latching member 228' extending into a slot 252 in the break-forcing member 216' and cooperating with ledge 234' thereof for latching purposes.

Figure 1 5 shows a typical socket accessory plate 1 50 having plug-pin entries at 152, its normal switch operator as rocker 1 6 and a test button at 1 52. The opposed spring action circuit breaking means will be in a convenient housing behind the plate 150, see dashed indication 154, with a drive solenoid indicated at 40 and a circuit board at 1 56 for suitable signal condition sensing and operation of the solenoid 40. Neon tell-tale shown at 1 58 is, of course optional, and the whole could be reorganised onto a normal size single plate for a switch-only accessory, i.e. omitting socket entries 1 52.

The further provisions of application no.

8404351 (P1119) regarding polarity assurance may, of course, be incorporated for the earth leakage detector, or those of our cofiled application no. (F1417).

Claims (23)

1. A switched electrical accessory having a switch operator for its normal make-and-break switch contacts and further make-and-break switch contacts with associated means of the accessory for effecting an operation of the further switch contacts that can be reversed or restored by operation of the switch operator.

2. A switched electrical accessory according to claim 1, wherein said operation of the further switch contacts is breaking the latter.

3. A switched electrical accessory according to claim 1 or claim 2, wherein said operation of the switch operator is movement thereof beyond that for effecting make of the normal switch contacts.

4. A switched electrical accessory according to any preceding claim, comprising means via which the switch operator is forced to its break position for the normal switch contacts when the associated means effects said operation of the further switch contacts.

5. A switched electrical accessory according to any preceding claim, wherein said associated means is responsive to earth leakage detection circuitry of the accessory for effecting said operation of the further switch contacts.

6. A switched electrical accessory comprising two sets of contacts connected in series for at least the "live" side for the accessory, one said set being associated for making and breaking with the normal switch operator of the accessory, and the other set being associated with means for breaking same independently of operation of said normal switch operation but then also moving said normal switch operator to its break position and breaking the contents of said one set, the normal switch operator further being operable to make or remake the contacts of said other set after making or remaking said one set.

7. A switched electrical accessory according to claim 6, wherein said associated means comprises a switch link movable between making and breaking positions for the contacts of said other set, releasable latch means for holding the switch link in its making position until the latch means is released, means then operative to ensure movement of the switch link to its breaking position and to resist movement back to its making position, and means operable by the switch operator to overcome the last mentioned means.

8. A switched electrical accessory according to claim 7, wherein said means then operative comprises a first bias applied to the spring link, said means operable by the switch operator includes a movable break-forcing member for the switch operator, the break-forcing member being subject to a second bias applied thereto in a direction towards breaking for the switch operator, the second bias then being greater than the opposing the first bias; said latch means comprises a latching member for holding the switch link and the breakforcing member together against both said biases until that latch member is released by associated circuit condition sensing means; and the latching member is subject to bias effective to reset its said holding when the break-forcing member is moved against the second bias and the first bias relative to the switch link.

9. A switched electrical accessory according to claim, 8, wherein the latching member is carried by the switch link for movement into and out of latching engagement with the break-forcing member.

1 0. A switched electrical accessory according to claim 8, wherein the latching member is carried by the break-forcing member for movement into and out of latching engagement with the switch link.

11. A switched electrical accessory according to claim 9 or claim 1 0, wherein said movement into and out of latching engagement involves swinging about its position by which it is so carried.

1 2. A switched electrical accessory according to claim 11, wherein said second bias acts to separate the break-forcing member and the switch link beyond possibility of said latching engagement without bias-resisted relative movement of the break-forcing member and the switch link.

1 3. A switched electrical accessory according to any one of claims 8 to 12, wherein each said bias comprises spring means.

1 4. A switched electrical accessory according to claim 1 3, wherein the first bias comprises compression spring means acting between said break-forcing member and a fixed part of the accessory.

1 5. A switched electrical accessory according to claim 1 3 or claim 14, wherein the second bias comprises compression spring means acting between the break-forcing member and the switch link.

16. A switched electrical accessory according to claim 1 3 or claim 14, wherein the second bias further affords the bias for the latching member.

1 7. A switched electrical accessory according to any one of claims 12 to 16, wherein the bias for the latching member is a third bias.

18. A switched electrical accessory according to claim 16 or claim 17, wherein the second bias or the third bias comprises an helical compression spring about an elongate part of the latching member and acts, against an abutment thereon.

1 9. A switched electrical accessory according to claims 16 and 18, with claim 9, wherein the helical compression spring so acts relative to the break-forcing member.

20. A switched electrical accessory according to claims 1 3 and 14, with claim 10, wherein the helical compression spring so acts relative to the switch link.

21. A switched electrical accessory according to any one of claims 6 to 20, wherein said switch operator is a rocker or dolly with further permitted but resisted movement thereof beyond its normal ON position in order to make or remake the contacts of said other set.

22. A switched electrical accessory according to claim 21, with claim 8, wherein said rocker or dolly has a nose part to engage on and move the break-forcing member.

23. A switched electrical accessory arranged and adapted to operate substantially as herein described with reference to and as shown in the accompanying drawings.