GB2213331A

GB2213331A - Key-operated plug to prevent unauthorised current use

Info

Publication number: GB2213331A
Application number: GB8828319A
Authority: GB
Inventors: George Morgan
Original assignee: PEKTRON Ltd
Current assignee: PEKTRON Ltd
Priority date: 1987-12-04
Filing date: 1988-12-05
Publication date: 1989-08-09
Also published as: GB8828319D0

Abstract

An electrical plug comprising a housing (10) and plug-in pins (12) has a switch body (18) in the cover (14) presenting a key aperture (20). A unique key inserted into the aperture (20) can move the plug between an "off" position wherein there is no electrical connection between one of the pins (12) and its respective terminal within the plug, and an "on" position wherein electrical connection is made. Thereby unauthorised use of a connected appliance may be prevented by switching off the plug. Alternatively the key may operate a mechanical interlock preventing insertion of the plug. <IMAGE>

Description

Electrical Plugs This invention relates to apparatus for providing electrical connection between a mains supply and an electrical appliance, particularly a plug for plug-in connection to a mains supply.

Heretofore electrical plugs to which cables from appliances are connected are connected to a mains supply by plugging into a suitable socket. Electrical power can therefore be made available to any particular appliance by anyone simply inserting the plug in the socl < et. Unauthorised use of certain equipment, for example highly sensi tive and/or expensive equipment such as hi-fi equipment in the home and computer equipment in the office, can damage the equipment and/or affect information for example stored in a computer.

According to the present invention there is provided apparatus for effecting electrical connection between a mains supply and an electrical appliance, the apparatus comprising terminal means for connection to electrical leads of the appliance, means for plug-in connection to the mains supply, and means for selectively preventing unauthorised completion of a circuit between the mains supply and the appliance.

Preferably the means for preventing circuit completion comprises switch means for selectively completing or breaking electrical connection between the terminal means and the plug-in means.

Alternatively the means for preventing circuit completion comprises means for selectively providing a mechanical interlock whereby to prevent plug-in connection to the mains supply.

The means for preventing circuit completion is preferably adapted For operation by a unique key. The latter may be engageable through a cover of the apparatus and is preferably engageable through that face of the cover opposite to the plug-il-l means.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing, the single figure of which is a perspective view of an apparatus according to the invention.

Referring to the drawing, an electrical plug, which can be generally of any conventional design, comprises a housing 10 from one face of which projects three pins 12 for plug-in to a socket whereby to connect with a mains supply. A cover 14 is provided for the housing 10 and is secured thereto by any suitable conventional arrangement, the housing 10 and the cover 14 providing for access into the housing 10 of a cable 16, the latter being connected at its other end to an electrical appliance (not shown).

The cable 16 has conventional electrical wiring for which respective terminals are provided within the housing 10.

In one arrangement an electrical connection between at least one of the terminals for the live and neutral wires and the respective pin 12 within the housing 10 can be selectively made or broken for example by an integral isolating switch (not shown). The latter provides a switch body 10 in the cover 14 presenting a key aperture 20. Insertion of a special or unique key (not shown) into the aperture 20 from externally of the plug can move the switch between an "off" position, wherein there is no electrical connection between the respective terminal and the pin 12, and an "on" position wherein electrical connection is made. The "on" and "off" positions of the switch are identified by marking of the outer surface of the cover 14.

Thereby the user of the electrical appliance may prevent unauthorised use o f the appliance by switching off the plug, insertion of the plug in the socket without use @ Une @es @@ swilch the pluy "un", not in itsolf enabling electricity to flow to the appliance.

In an alternative arrangement the terminals may be permanently in electrical connection with the respective pins 12, but operation of the key may be adapted to provide a mechanical interlock, for example by rotating the earth pin 12 whereby it is not possible to insert the plug into a socket.

It is to be appreciated that any other suitable switching arrangement may be adopted provided the authorised user can selectively and uniquely control completion of a circuit between the main supply and the appliance.

The invention therefore provides the designated user or owner of valuable or sensitive electrical equipment with the possibility of ensuring that an electrical supple is only available to the appliance by the operation of a personal key.

It is preferred that the plug is so designed as to be difficult to disconnect from the cable of the electrical appliance so that any attempt to open the plug, or sever or re-connect the cable to the plug leads to visible evidence of interference.

Various modifications may be made without departing from the invention. For example the configuration of the plug may differ from that described and shown and the key operated switch may also differ from that described and shown.

Claims

Claims:

1. Apparatus for effecting electrical connection between a mains supply and an electrical appliance, the apparatus comprising terminal means for connection to electrical leads of the appliance, means for plug-in connection to the mains supply, and means for selectively preventing unauthorised completion of a circuit between the mains supply and the appliance.

2. Apparatus according to Claim 1, wherein the means for preventing circuit completion comprises switch means for selectively completing or breaking electrical connection between the terminal means and the plug-in means.

3. Apparatus according to Claim 1, wherein the means For preventing circuit completion comprises means for selectively providing a mechanical interlock whereby to prevent plug-in connection to the mains supply.

4. Apparatus according to any of Claims 1 to 3, wherein means for preventing circuit completion is adapted for operation by a unique key.

5. Apparatus according to Claim 4, wherein the unique key is engageable through a cover of the apparatus.

G. Apparatus according to Claim 5, wherein the unique key is engageable through that face of the cover opposite to the plug-in means.

7. Apparatus for effecting electrical connection between a mains supply and an electrical appliance, substantially as hereinbefore described with reference to the accompanying drawings.

8. Ans novel subject matter or combination including novel subject matter herein disclosed in the foregoing Specification or Claims and/or shown in the drawings, whether o r not within the scope of or relating to the same invention as any of the preceding Claim