GB2218274A

GB2218274A - Electrical power control

Info

Publication number: GB2218274A
Application number: GB8904387A
Authority: GB
Inventors: Bernard William Gill
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-02-27
Filing date: 1989-02-27
Publication date: 1989-11-08
Also published as: GB8804629D0; GB8904387D0

Abstract

A multiway power distribution device 20 has a mains plug (not shown) at its rear and a master socket 21 and a plurality of slave sockets 22 on its front. The master socket is permanently energized. The slave sockets are normally not energized, but sensing and control circuitry senses (Fig. 3) when power is being drawn through the master socket 21, and in response thereto, energizes the slave sockets. Units of apparatus plugged into the slave sockets can therefore be left permanently switched on; the device 20 energizes and de-energizes them automatically as apparatus plugged into the master socket is turned on and off. Indicator means indicate when the master output (lamp 24) and the slave outputs (lamp 25) are energized, and the slave outputs can be switched on independently of the sensing and control circuitry by an over-ride switch. The sensing and control circuitry can comprise a relay or electronic circuitry e.g. including a triac. <IMAGE>

Description

Fm t e c t ic i c Powder Gont rol The present invention relates to electric power control.

There are various situations, both domestic and commercial, where an electrical and/or electronic system includes two or more units which require separate power supplies. A major example is a computer system, which may consist for- instance of a main processor unit, a monitor, a keyboard, and a printer; of these units, the main processor unit, the monitor, and the printer may all require their own power supplies. Another example is a television set and video recorder unit. A further example is an audio system, which may consist for instance of a tape unit, a phonogram unit radio/amplifier unit, and loudspeakers; of these units, the tape unit, the phonogram unit, and the radio/amplifier unit may all require their own.power supplies.

In such systems, each of the various units requiring their individual power supplies generally (though not necessarily) has a mains lead emerging from its rear. Each of these leads is usually terminated by its own plug (usually a standard 13 A 3-pin plug), and these plugs are plugged into a mains supply. If there are only two leads, they may be plugged into the two sockets of a double socket. More commonly, however, there are more leads than sockets: the socket may be a single socket, or there may be more than two leads, or the socket may be a double socket but with some other appliance not forming part of the system also fed from that socket (e.g. a television being fed from the same socket as an audio system). In such cases, some form of multiway adaptor is used.Such an adaptor consists of a plug portion which fits into the standard socket, and a plurality of socket portions each of which will receive a standard plug, and is usually either å 2-way or 3-way block or a multi-way strip.

Such units normally all have their own mains switches. This means that when the system is to be switched on, all the various units have to be switched on individually, and conversely all the units have to be switched off individually when the system is to be switched off. While this is not an onerous task, it is nevertheless subject to various minor disadvantages. For example, the need to switch several units on ahd off when they form a single system is contrary to many users' sense of good order. It is irritating if the user torgets to switch on all the units and starts trying to use the system before realizing this.

There is also a danger of a unit being accidentally left switched on when the system is being switched off, with accelerated ageing of that unit as a result.

It is of course possible to use the switch on the mains socket to switch the system on and off, with all the units themselves being left permanently switched on, but the mains switch may not be easily accessible, and it is easy for the user to switch some of the individual units off when switching the system off again not a matter of great moment but a minor irritation when the system is being switched on again.

The main object of the present invention is to provide means whereby, with a system having a plurality of independently powered units, the powering on and off of all such units is automatically controlled by the switching on and off of one particular one of such units.

Accordingly the present invention provides a multiway power distribution device having input means for receiving a power supply and a plurality of output means for providing power outputs, and sensing means for sensing whether power is being drawn through a predetermined one of the output means fthe master) and switching the remaining output means (the slave or slaves) on and off accordingly.

The device may include indicator means for indicating when the master output and the slave outputs are energized, and an over-ride switch for switching the slave outputs on independently of the sensing means. Further features of the invention will become apparent from the following detailed description.

Various mains distribution devices embodying the invention will now be described, by way of example, with reference to the drawings, in which: Fig. 1 is a perspective view of a 2-way adaptor embodying the invention; Fig. 2 is a front view of a multi-way adaptor embodying the invention; and Fig. 3 is a circuit diagram of the multi-way adaptor.

Fig, 1 shows a 2-way adaptor 10. This is roughly cubical, having a standard 13 A 3-pin plug provided on its rear face 11 (two of the pins 12 being partially visible in the drawing). Its front face 13 is formed as a standard 13 A 3-pin socket, and this is the master socket of the adaptor; the letter "M" formed on this face indicates its masterhood. Its top face 14 is also formed as a 13 A 3-pin socket, and this is the slave socket of the adaptor; the letter "S" .on this face indicates this.

Fig. 2 shows a multi-way strip adaptor. This has a master socket 21 and three slave sockets 22 formed on.its front as shown, all of which are standard 13 A 3-pin sockets, and a standard 13 A 3-pin plug (not shown) provided on its back like that on the adaptor 10 of Fig. 1. (A plug connected to the adaptor by a flex could be used instead.) An over-ride switch 23 is provided between the master socket 21 and the slave sockets 22. There is a mains power signal light 24 on the corner of the adaptor adjacent to the master socket 21, and a slave power on signal light 25 on the opposite top corner. A pair of arrows 26 are formed on the adaptor as shown, to indicate that the switch 23 controls a power flow path from the mains supply to the slave sockets 22, and a further arrow 27 is similarly formed as shown to indicate that the master socket controls another power path.A fuse 27 is mounted in the left-hand end of the adaptor.

A master control switch can obviously be provided on the adaptor, to provide switching for the master socket.

The basic function of these adaptors is that power is permanently fed from the rear plug to the master socket, and internal control means sense the drawing of power from the master socket and switch the slave sockets on and off according as power is or is not being drawn from the master socket.

These adaptors are intended for use with a system having a plurality of independently powered units, as described above. One of the units is selected as the master unit and its mains lead is plugged into the master socket (13 or 21); the mains leads of the remaining units are plugged into the slave socket or sockets (14 or 22), and are left permanently switched on. With these adaptors, the slave sockets are normally switched off inside the adaptor. However, when the master unit is switched on by means of the mains switch on that unit, it will draw power through the master socket of the adaptor; this will be sensed by the circuitry in the adaptor, and the slave sockets will be switched on in the adaptor, so turning on the various other units of the system.When the master unit is turned off by the mains switch on it, the adaptor will sense that no power is being drawn through' the master socket and will switch off the slave sockets.

If the system is a computer system, then the monitor will usually be chosen as the master unit, since the user normally sits in front of the monitor when using the system and the mains switch on the monitor is then readily accessible.

In this case, the remaining units will normally be left permanently switched on indeed, the user may think it worth while taping over their mains switches in the on position so that they are not inadvertently turned off. If the system is a television and video recorder, then the video recorder will usually be chosen as the master unit. In this case, the mains switch on the television may be used to turn the television off when only the video recorder is required to be on; the video recorder can normally be left on safely in the stand-by mode when it is not being used for recording or play back. In the case of an audio system, the master unit would normally be the main amplifier/radio tuner unit.

Fig. 3 shows the circuitry of the adaptor 20 of Fig. 2. The plug on its rear is shown diagrammatically at 30 as three pins (earth E, neutral N, and live L). The earth pin E is connected directly to the earth holes of the master socket 21 and the slave sockets 22, and the neutral pin N is connected directly to the neutral holes of these sockets. The live pin L is connected tQ the live hole of the master socket 21 through the fuse 27 and the winding 31 of a relay, and through the fuse and the contacts 32 of the relay to the neutral holes of the slave sockets 22. The relay may be a reed relay, and its winding 31 is a "current" winding - i.e. of heavy gauge conductor and with relatively few turns.

The switch 23 is connected in parallel with the contacts 32; the signal light 24 is connected directly across the mains supply from the plug 30, and the signal light 25 is connected across the live and neutral holes of the slave sockets 22.

The operation of the adaptor is obvious. The master socket 21 is always energized directly from the plug 30, while the slave sockets 22 are energized only when sufficient current is drawn through the master socket 21 to operate the relay. The sensitivity of the relay is chosen at a suitable value so that the power drawn by most likely master units when turned on is sufficient to operate it.It may however be set, for example, at a level such that the "off" mode of a unit such as a video recorder is insufficient to operate it. (The "off" mode of such a unit may often draw power, but only the small amount required to keep an internal time and day clock running and keep sensing circuitry operative to sense remote control signals.) Means (not shown) may be provided to allow the sensitivity to be adjusted, e.g, by rotating the winding 31 sbout the contacts 32 or moving an iron slug to and fro in the field of the winding 31.

The circuitry of the adaptor 10 of Fig. 1 is similar, except that the override switch and signal lights are omitted and there is only one slave socket.

(It is possible to provide further slave sockets on further faces of the adaptor 10 if desired.) It will of course be realized that electronic circuitry may be provided to sense the drawing of power from the master socket 21 and switch power to the slave sockets 22 accordingly. Such circuitry might for example include a low voltage power supply energized from the plug 30, a sensing resistor of low resistance in place of the winding 31, sensing circuitry, and a triac controlled therefrom in place of the contacts 32. Similarly, some other form of circuit breaking, e.g. operating electronically and/or on the sensing of a current imbalance between live and neutral as well as or instead of a current overload, could be used in place of the fuse 27. Also, it may be desirable for the adaptors to incorporate surge suppression circuitry; this is particularly appropriate, since a major use of them is with computer systems.

The invention can also be embodied in, for example, an "in-line" device which has the various mains leads permanently wired to it; a similar device with "in-line" plugs and sockets; or a similar device which may have the master output means in the form of a plug which will plug directly into the back of the master unit and the slave output means of the form of sockets which will receive plugs with leads to the remaining units of the system. Such plugs and sockets may be of the flat or nearly flat type.

Claims

1 A multiway power distribution device having input means for receiving a power supply and a plurality of output means for providing power outputs, and sensing means for sensing whether power is being drawn through a predetermined one of the output means (the master) and switching the remaining output means (the slave or slaves) on and off accordingly.

2 A multiway power distribution device according to claim 1 including indicator means for indicating when the device, the master output, and/or the slave outputs are energized.

3 A multiway power distribution device according to either previous claim including an over-ride switch for switching the slave outputs on independently of the sensing means.

4 A multiway power distribution device according to any previous claim including a switch for controlling the master socket.

5 A multiway power distribution device substantially as herein described and illustrated.