GB2276503A - Connection device with circuit breaker - Google Patents

Abstract

A device for connecting electrical apparatus to a mains supply comprises a current controlled circuit breaker in the housing of the device and incorporated in the live conductor, the breaker being exposed to the ambient atmosphere in the device. In the embodiment, an adaptor having three sockets 30 includes a resettable single pole circuit breaker 20 and a neon lamp 40. The breaker 20 may a temperature sensitive actuating device e.g. a bi-metallic strip, and is exposed to the ambient atmosphere by vent slots 21. The breaker is reset by the button 25. An audio or visual alarm responsive to the breaker may be included. The device can also be a plug or a socket. <IMAGE>

Description

CONNECTION DEVICE The present invention relates to a safety device for mains power connection devices such as plugs, spurs, connection units, sockets or adaptors. In particular it relates to a safety device for a connecting device to a mains AC power supply circuit with a plurality of output sockets each for providing power to apparatus such as household appliances.

In general, fuses are included in the live conductor from the mains to mains powered appliances.

They are usually placed in at least some of the following: the mains power ring, wall sockets, electrical plugs, adaptors if they are used and the appliances themselves. Fuses used in the mains power ring are generally of a type that may easily be reset after tripping, but are bulky and expensive. Fuses used in plugs and adaptors are generally of a type that must be replaced after tripping, which occurs when a sufficient temperature rise, resulting from their dissipation of power, causes them to melt and break, they may act relatively slowly.

At present British Safety Standard requirements may be met by incorporating fuses of these types provided that all other features also conform to the relevant Standards. It is believed however, that the safety of tripping mechanisms for power supply to appliances such as domestic mains-supplied appliances could be improved by incorporating a circuit breaker of a type whose threshold for tripping is a current threshold.

According to the present invention there is provided a connection device in the form of a current control device for connecting an electrical apparatus to a mains power supply wherein a current controlled circuit breaker is provided in the device and is in the live conductor circuit in the device.

Preferably the device is an adaptor comprising a plurality of sockets and is a fused current control device.

An embodiment of the present invention will now be described with reference to the Figure which shows a circuit diagram of a three-way adaptor.

Referring to the Figure a fused current control device 1 is in the form of an adaptor containing three output sockets 30. The device 1 has connection points L, E, N, corresponding to the live 10a, earth 10b and neutral 10c conductors respectively of a mains power supply 10 of 100-240 V, for example. The output sockets 30 are connected to the connection points L, E, N, in a standard manner so as to be in parallel with one another. Connection points L1, El and N1 of the first socket SKT1 are for the live, earth and neutral pins respectively of a plug of an electrical apparatus (not shown) such as a domestic appliance. The second and third sockets are similar. A fuse 15 such as a 13 amp mains fuse in the example of a device for connection to a standard United Kingdom mains source, and a resettable single pole current controlled circuit breaker 20 are connected in series between the connection point 104 to the live terminal of the mains power supply 10 and the live connection points L1, L2, L3 of the output sockets 30.

The circuit beaker 20 is of a type which utilizes a bi-metallic strip or other temperature sensitive actuating member which is exposed to the ambient atmosphere within the adaptor body by means such as vent slots 21 in the housing of the circuit breaker 20. Thus, should the temperature within the device 1 over riGa for any reason such as faulty wiring connectors, the circuit breaker will trip earlier than normal in order to ensure that incipient fire risks are avoided.

To operate the adaptor, a reset button 25 must be in a latched position. When the adaptor is connected to the mains power supply and the reset button is in the latched position, a neon indicator 40 glows to indicate that the sockets are in a ready state for supplying power to apparatus such as domestic appliances, and other such loads.

With loads drawing up to 13 amps the adaptor will function as a normal three way adaptor. If however, the current exceeds 13 amps the adaptor will trip within a given time and disconnect the sockets from the supply. In order to reconnect the sockets, the reset button 25 must be moved again to the latched position. This can only occur if the load current has been reduced to a value less than the trip value of the circuit breaker 20.

In a further variation of the invention an alarm, responsive to the circuit breaker 20, may be included in the device. This is not shown in the drawings but may be any known alarm device which is configured to be responsive to the state of the circuit breaker and to give an audio and/or visual alarm when the circuit breaker has tripped. This will give an indication that the device incorporating the invention is not operational and requires re-setting. Clearly, in order for such an alarm to be capable of such operation it must either be connected to the electrical supply on the supply side of the circuit breaker, or it must include an independent power supply which is not affected by the tripping of the circuit breaker.

In the above description, the invention has been described in relation to a connection device in the form of a three-way adaptor. Other embodiments do not necessarily have three output sockets since the supplementary protection provided by current contrdl is equally applicable to adaptors with any numbers of output sockets, for example multi-way bars, multi-way extension leads or multi-way wall socket adaptors. The invention is also equally applicable to other types of connection devices such as the sockets themselves, spurs, or individual plugs.

The sockets in the adaptor of the above description and in the Figure are of the three pin 13 amp type standard in the United Kingdom. The connection device of the present invention does not depend on the presence of an earth connection, and the invention is thus equally applicable to adaptors with other types of sockets such as the two-pin sockets used in other countries. Corresponding embodiments related to the two-pin sockets themselves, two pin plugs or unearthed spurs may be envisaged.

For the current control feature to operate successfully, it is not necessary for the connection device to include a fuse. Versions of all of the above embodiments may therefore be envisaged with or without fuses in the connection device.

Claims (5)

1. A connection device for connecting an electrical apparatus to a mains power supply wherein a current controlled circuit breaker is provided in a housing of the connection device and is incorporated in the live conductor circuit in the device the circuit breaker having an actuating member exposed to the ambient atmosphere within the device.

2. A connection device according to claim 1, wherein the connection device is a plug, a socket or a multi-way adaptor.

3. A connection device according to claim 1 or 2 wherein the current controlled circuit breaker is a resettable, single pole circuit breaker.

4. A connection device according to claim 1, 2 or 3 wherein the live conductor circuit includes a fuse.

5. A connection device according to any one of the preceding claims wherein the connection device is adapted for use with a mains electrical appliance.