GB2186445A

GB2186445A - Socket having residual current circuit breaker

Info

Publication number: GB2186445A
Application number: GB08703117A
Authority: GB
Inventors: D M Brown
Original assignee: B & R Electrical Prod Ltd
Current assignee: B & R Electrical Prod Ltd
Priority date: 1986-02-11
Filing date: 1987-02-11
Publication date: 1987-08-12
Anticipated expiration: 2007-02-11
Also published as: GB8603281D0; GB2186445B; GB8703117D0

Abstract

A shuttered mains supply socket for an electrical plug includes a RCCB and a reset button (48) for the RCCB is mounted in a face of the socket. In order to prevent the RCCB being reset while an electrical plug is mounted in the socket, an edge of a shutter (16) engages an edge of a sliding bar (36) so that movement of the shutter upon insertion of an electrical plug moves the sliding bar (36) to a position beneath the reset button (48) in order to prevent resetting of the RCCB. A twin socket outlet embodiment is also disclosed. <IMAGE>

Description

SPECIFICATION Residual current circuit breaker This invention relates to residual current circuit breakers.

It is common to locate a residual current circuit breaker in a mains supply socket so that upon installation of a plug in the socket and operation of electrical equipment connected thereto any dangerous out of balance condition between the currentflowing through the live wire and the current flowing through the neutral wire may be detected and the mains supply cut off in response to a dangerous condition of unbalance in order to prevent damage to electrical equipment.

Normally, a residual current circuit breaker (hereinafter referred to as an RCCB) has a reset switch associated therewith so that if the RCCB should trip, it is possibleto reset the device by depressing the switch button when the fault has been attended to. However, when designing equipmentfor use by the general public it must be assumed thatthe equipment will be operated by people unfamiliar with electrical principles and the provision of an RCCB button for resetting the device brings with it the danger that a person may resetthe equipment without first attending to the fault which has caused the RCCB to trip.Accordingly the object of the present invention is to prevent operation ofthe reset switch button during use of the electrical equipment and the invention accordingly provides a mains supply socketfor a electrical plug, the socket having connected thereto a residual current circuit breaker, a reset switch button for the circuit breaker being mounted in a face of the socket for access by a user, the socket having apertures registering with socket terminals for permitting insertion of an electrical plug, wherein a shutter is provided normally covering the socket apertures but which is automatically movable against spring bias means upon insertion into the socket apertures of the pins of an electrical plug,theshutterbeingcoupledwitha locking memberwherebysuch movementofthe shutter causes movement of the locking member to a position in which movement of said button for a resetting operation is prevented.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein: Figure lisa top view of a single socket forming a first embodimentto the invention; Figure 2 is a side sectiona I view of the socket together with a plug; Figure 3 is a view of the front face of a double socket forming a second embodiment of the invention; Figure4 is a view of the double socket of Figure 3 with the front face plate removed; and Figure 5is a cross sectional view on the line A-A of Figure 4.

Referring now to the drawings a socket 2 is shown for a mains power supply having three apertures 4,6 and 8 registering with socket terminals (not shown) for receiving the pins 10, 12 and 14 of a plug 16, which plug is connected to electrical equipment to be powered by the main supply. A shutter 18 is provided which covers the apertures 4,6 and 8when the pins of the plug are not inserted into the socket.

As shown in Figure 1 the shutter 18 has a general T-shapewith a longitudinal arm 20 half covering in the inoperative position the aperture to the earth pin 4 and a cross arm of the T 22 covering both live and neutral apertures 6 and 8. The cross arm 22 has tapering surfaces 24 and 26. A spring 28 is located within a slot 30 within the arm 20 of the shutter and is held against a fixed projection 32 that when a plug is inserted into the socket the shutter is moved downwardly under the force of the earth pin being inserted into the earth aperture and when the plug is subsequently removed the spring 30 by acting against stationary projection 32 pushes the shutter backtothe inoperative position.

The right-hand edge of the arm 22 of the shutter indicated at34 engages the bevelled free end of a bar member 36 which slides into slot 38. The slide member 36 has a slot 40 disposed therein in which is disposed a spring 42 acting against a stationary projection 44. The bar member has a recess portion 46 as shown in Figure 2 which is adapted to slide beneath a push-button 48 of a reset switch of a residual current circuit breaker. It will be understood that the electrical parts of the reset switch are not shown but are conventional as is the residual current circuit breaker which is also not shown.Figure 2 shows a cross-sectional view ofthe mechanical parts of the shutter and slide member 36 and it will be seen they are mounted in a position member 50 which is joined to the upper surface 52 of the socket so asto form an enclosurewhich housesthe shutter and slide member 36.

It will be seen that in operation when a plug 16 is inserted into the socket so that the shutter 18 moves downwardly the bar member 36 moves transversely in slot 38 so asto be positioned beneath the reset switch 48. In this configuration, electrical power can be supplied to the equipment attached to the plug. If a fault arises so that the current supplied bythe mainsisoutofbalancethe RCCBwill operate causing the powersupplyto become disconnected.

The bar member 36 being positioned beneath the rest button 48 prevents resetting of the RCCB until the plug is removed in which position the bar member slides backtowardstheshutterandthereby permits the reset button to reset to RCCB.

Referring now to Figures 3,4 and 5, there is shown a double socketforming a second embodiment of the invention. The socket comprises a face plate 60 having first and second sockets 62,64 and the socket also includes an RCCB having a reset button 66 and a trip button 68.

Figure 4 shows the socket with the face plate removed and it may be seen thatthe body of the socket 68 is molded to form a network of ribs 70 which form enclosures fortwo shutters 72 of identical construction covering each set of socket apertures and socket terminals (not shown) each shutter is generally T-shaped with a longitudinal arm 74 and a cross arm 76. The upper end of longitudinal arm 74 is contoured as shown and beveled as at78 so that pressure of an earth pin of a plug inserted into the earth aperture pushes the shutter downwardly. A longitudinal aperture 80 in arm 74 houses a spring 82 which is biased between stationary projection 84 and the opposite end of recess 80. The ends of the cross arm 76 have triangular recesses 86 formed in the uppersurface which define angled edges 88. The lower surfaces of the edges of cross arm 76 are also recessed as at 90.Sliding bar members 92 are provided having an angled edge 94which co-operates with angled edge 88 of shutter 74. The sliding bar members have recess 96 in which are disposed compression springs 98 biased between an edge of recess 96 and a stationary projection member 100. Referring to Figure 5, which is a sectional view along line A-A of Figure 3 it will be observed that sliding bar members 92 are shaped so that an edge portion 102 bearing tapering edge 94 engages within a recess 86 of shutter72. The other end of sliding bar 92 extends downwardiy and has an end portion 104 disposed beneath a rectangular recessed portion 106. Reset button 66 of the RCCB as shown in Figure 5 has a circumferentially extending flange 108 and a spring 1 which extends upwardly into the reset button to biased the button upwardly.

Thus in operation if a plug is inserted into either of the sockets 62,64 the respective shutter 72 slides downwardly and interengaging edges 88,94 cause sliding bar member92 to moveto a position in which end portion 104 is disposed directly below reset button 66 whereby reset button 66 can only be moved down a limited extent into recess portion 106 but cannot be moved to its full extent in orderto cause resetting of the RCCB, should the RCCB have tripped for any reason.

Thus itwill be observed in the embodiment of Figures 3to 5, insertion of a plug into either of the socketswill preventthe RCCBfrom being reset. This is of particuiar advantage where a double socket arrangementisemployedsinceitwill preventa possibly dangerous situation where both sockets are being employed by different users. In this situation a malfunction of electrical equipment being used by one user may cause the RCCB to trip and the user, assuming that no power is being supplied to his equipmentmayattempttodismantletheequipment tofind the cause ofthe error. In the meantimethe user of the other socket mayattemptto resetthe RCCB in orderto continue using his equipment.

However in accordance with the embodimentshown in Figures 3to Sthis is not possible and clearlywould avoid the dangerous situation of electrical power being supplied to equipment which is being dismantled by the other user. In accordance with this embodiment, resetting is only possible if both plugs are withdrawn from the socket.

Claims

1. A means supply socket for an electrical plug, thesockethaving connected thereto a residual current circuit breaker, a reset switch button for the circuit breaker being mounted in a face ofthe socket for access by a user, the socket having apertures registering with socketterminals for permitting insertion of an electrical plug, wherein a shutter is provided normally covering the socket apertures but which is automatically movable against spring bias means upon insertion into the socket apertures of the pins of an electrical plug, the shutter being coupled with a locking memberwherebysuch movement of the shutter causes movement of the locking member to a position in which movement of said button for a resetting operation is prevented.

2. Asocketaccording to claim 1 including a partition member secured on to a socketface plate and defining therebetween an enclosure for said shutter locking member.

3. A socket according to claim 1 or 2 wherein the shutter is generallyT-shaped, with the longitudinal arm of the T covering the earth socket terminal and the cross arm of the T covering the live and neutral socket terminals.

4. Asocketaccordingto claim 3 wherein the longitudinal arm has a recess enclosing a spring which acts between a recess wall and afixed projection in orderto bias the shutter to aterminal covering position.

5. A socket according to claim 3 or 4wherein the cross arm has a tapering surface engaging a tapering surface of the locking member to move the locking member in a required direction.

6. A socket according to claim 3,4 or 5wherein the cross arm has a recess enclosing a spring which acts between a recess wall and a fixed projection in orderto bias the locking member to a position in which the reset switch button isfreeto move.

7. A socket according to any of claims 3 to 6 wherein the locking member has an end adapted to move beneath the reset switch button for preventing movement ofthe button.

8. A socket according to any preceding claim, incorporated in a double socket comprising two sockets each for a respective electrical plug, and a single residual circuit breaker and single reset button serving both sockets, wherein each socket includes a said shutter and a said locking member.

9. Mains supply sockets substantially as described with reference to the accompanying drawings.