GB2274171A - Electricity monitor - Google Patents

Abstract

An electric power monitoring device provides information on an integral display (25) about the cost of operating electrical appliances. The device can be couplable through terminals (12) or an induction pick-up, or other releasable coupling to the electric power supply of the appliance. Power consumption is derived by a micro-processor from measurement of the voltage and current of the power supply carried out by a processor or by a measurement of a current induced in an inductive pick-up by the power supply. Cost is derived from the power value by the micro-controller programmed with the cost per unit of electrical energy and the rate of tax and is displayed on the display. User-operable programming keys (30, 31) are provided for programming the micro-controller. <IMAGE>

Description

ELECTRICITY MONITOR The present invention relates to a monitor for monitoring the consumption of electricity.

The standard way of monitoring the consumption of electricity is by way of a meter connected to a mains supply. The meter monitors the total consumption of electricity of all appliances connected to the mains supply at a particular site, and produces a numeric measurement. The electricity supplier then converts that numeric measurement to a cost measurement, in the form of a bill.

From the consumer1 5 point of view, however, the information generated by the meter is less useful.

The relationship between the numerical values generated by the meter and the resulting bill is not immediately apparent. Moreover, since the monitoring of electricity is for the whole of the mains supply to all appliances, it is not easy to make the correct decisions about reducing consumption by controlled use of the appliances.

The present invention seeks to permit the consumer to obtain a cost measurement of the electrical power consumed by one or a group of the appliances connected to a mains supply. At its most general, the present invention proposes that a device be provided which monitors the power consumed by an appliance, or group of appliances, which converts that power measurement to a cost measurement, and which then displays that cost measurement by a display in the device itself. Thus, an immediate visual measurement of the power consumed by the appliance, or group of appliances, is obtained at or near the location of the appliance(s), rather than at a single point (the meter) for the whole of the mains supply.

Within this general concept, the present invention proposes a range of devices for generating the cost of the power consumed by an appliance, or group of appliances. A first group of such devices are those which are connected into the electricity supply between the mains and the appliance or group of appliances. They will thus have input and output terminals respectively connected to the mains supply and to the appliance(s). Means interconnecting those terminals is then monitored to determine the current and voltage therein, thereby to derive a power measurement.

In such an arrangement, the device may be a plug/socket arrangement in which the input terminals include pins insertable in an electric socket, and apertures are associated with the output terminals into which pins of a plug connected to the appliance(s) may be inserted. The appearance is then similar to an adaptor plug, but with a display in the housing thereof.

Alternatively, the device may be in the form of a socket which is wired to the electricity supply, so that it may be visually similar to a standard socket, but again with a display for measuring the power consumed by an appliance which is plugged into the socket. In a further alternative, suitable for use e.g. where one appliance will be permanently connected to the supply at that particular site, there need be no socket, so that a cable to the appliance emerges from the housing.

In all such arrangements, the power supply between the input and output terminals may be interruptible by a switch, e.g. as in a standard socket.

Although some of the devices discussed above will normally be mounted so that they are fixed to the power supply at a particular site, the device which comprises pins and socket is portable. Thus, it may be transported from one site to another, to measure the power consumed, and cost, of different appliances at different times. Other portable arrangements are also possible, however, within the present invention.

For example, a portable unit may have an inductive pick-up which is mountable on a cable leading to an appliance, so that the power consumed by the appliance may be measured without having to disconnect the appliance from its supply. In another alternative, the device may have a sensor which may be inserted into part of the electrical connection to the appliance, for example by replacing the fuse in the supply to the appliance, so that the power consumption may again be measured. In such an arrangement, it can be seen that it is also possible to measure the power consumed, and cost, of a group of appliances which are all connected to that single fuse.

Furthermore, this idea of measuring a group of appliances may be applied to the arrangement consisting of a plug and socket, since the provision of a plurality of sockets permits a plurality of appliances to be connected to the device. A single display may be provided, but it is preferable that each socket has a corresponding display, so that measurements can be provided for each appliance.

In all such arrangements, there is preferably means for varying the conversion rate by which the device converts a power measurement to a cost measurement. The suppliers of electricity may vary their tariff, and the conversion rate will then have to be converted accordingly. Furthermore, it may be necessary to alter other factors in the generation of a cost measurement, such as variations in VAT. In such circumstances, separate controls may be provided for varying VAT and the tariff conversion.

Embodiments of the present inventionswill now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a first embodiment of the invention, being a plug and socket device; Fig. 2 shows schematically the electrical circuitry of the device of Fig. 1; Fig. 3 shows a second embodiment of the invention, being a socket; Fig. 4 shows a third embodiment of the present invention, being similar to that of Fig. 3, but where the electrical output is fixed to the device; Fig. 5 shows a fourth embodiment of the present invention, in which a plurality of sockets are connected to a single input cable; Fig. 6 shows a fifth embodiment of the present invention, which has an inductive pick-up; and Fig. 7 shows a sixth embodiment of the present invention which has a current/voltage sensor.

A first embodiment of the present invention is shown in Fig. 1 and 2. As can be seen from Fig. 1, an electricity monitor is in the form of a device comprising a housing 10, which has apertures therein 11 which define a socket which confirms with to a standard 3-pin plug, and are thus capable of receiving pins of a plug connected by a suitable cable to an electrical appliance. The device is then connected to a mains power supply via pins 12, which again conform to a standard 3-pin plug so that they may be plugged into a standard socket. This will create an electrical connection between the mains supply and the appliance, causing current to flow through the device.

The electrical circuitry of the device of Fig. 1 is shown in more detail in Fig. 2. Wires 20 connecting the pins 12 and output terminal 13 associated with the apertures 11 are also connected via wires 21 to a processor 22. That processor generates the current and voltage measurement signals from the wires 20, which signals are passed in analog manner to a micro controller 23. The current measurement is derived from the voltage drop across a resistor 28, and the voltage measurement is obtained directly from the live and neutral wires. The microcontroller 23 includes an analog to digital converter 24 which converts the measurement signals to digital signals, which are processed by the micro-controller to obtain a power measurement which is then converted to a cost measurement based on conversion rates stored in the micro-controller. That cost measurement is converted to a visual display on a display 25.

As can be seen from Fig. 1, the display 25 is visible from exterior from the housing 10, so that the user can see the power consumed by the appliance connected to the device. The processor 22 and the micro-controller 23 may be powered from a power supply 26 which is connected to wires 21, so that it derives its power source from the moving supply via wires 20.

However, to prevent loss of information from the micro-controller when it is disconnected from the moving supply, a back-up battery 27 may be provided.

The conversion of the power measurement to a cost measurement, and subsequent display of that cost measurement, is controlled by the micro-processor 23.

To carry out that conversion, the micro-controller 23 will use conversion rates based on tariff values and/or other values such as VAT stored in memories of the micro-controller 23. Since the tariff values and/or the VAT may change, controls 30,31 may be provided in the housing 10 for varying the rates of conversion. In the embodiment of Fig. 1, two such controls are provided which determine the conversion rates carried out by the micro-controller 23 by suitable programming thereof.

Thus, this embodiment provides a portable device for measuring the power consumed by an appliance or appliances connected thereto, and provides a visual display of the cost. Although that cost measurement is normally given as a monetary value, it could, for example, relate to environmental cost such as CO2 production.

Fig. 3 shows a second embodiment of the present invention. In this embodiment, the housing 10 corresponds in outward appearance to a standard socket and thus has apertures 11 defining a socket in a similar way to the embodiment of Fig. 1. However, unlike the embodiment of Fig. 1, the housing 10 is to be mounted on e.g. a wall, as is usual for a socket, and thus an electrical cable 40 extends from the back of the socket, being electrically connected to suitable terminals in a way which is conventional for a socket. As is also conventional, a switch 41 may be provided for disconnecting the input and output terminals of the device when desired. Thus, again, an immediate visual display of the cost of an appliance or appliances connected to the socket is provided on the display.

The electrical circuitry of this embodiment may be similar to that shown in Fig. 2, and thus will not be described in more detail now. However, as shown in Fig. 3, this device has three controls 42, 43, 44 for varying the conversion rates used by the microcontroller 23. One of those controls (e.g. control 42) is used to select either the tariff conversion or the VAT rate and the other two controls 43, 44 are respectively for increasing and decreasing the conversion rate used. The first control 42 may also be used to vary the period of monitoring, e.g. hour, day, etc. Means (not shown) may be provided to lock or disable the controls 42,43,44 to prevent accidental or erronous changes.

In some situations, e.g. for an immersion heater, it is not. necessary to disconnect the appliance from the measuring device. This is shown in the embodiment of Fig. 4, which is generally similar to the embodiment of Fig. 3, and the same reference numerals are used to indicate corresponding parts. In the embodiment of Fig. 4, however, no apertures 11 are provided; instead a cable 50 extends from the housing 10 to the appliance. The cable 50 will be connected to suitable output terminals within the housing 10 in a conventional way.

A further variation on the embodiment of Fig. 3 is shown in Fig. 5. In that embodiment, the housing 10 has three sockets, each with associated apertures Ila, 11b and llc. Separate displays 25a, 25b, 25c are associated with each set of apertures so that separate appliances may be plugged into each set of apertures gila, lib, lic and corresponding cost measurements displayed on the displays 25a, 25b, 25c. In the embodiment of Fig. 5, common programming controls 42, 43, 44 are provided for all the displays. Separate controls may be provided, if desired. Alternatively, a single display may be provided which either displays a total power measurement for all appliances connected to the device, or is switchable between the various appliances.

In all the above embodiments, the monitoring device is connected so that it has a part which forms part of the power supply path from a power source to the electrical appliance. Fig. 6 illustrates a further embodiment, in which a clamp 60vof e.g.mild steel is connected to the housing via a cable 61. The clamp 60 has a slot 62 for receiving a cable connecting an appliance to a power source, and the clamp 60 derives measurements on the electricity supply in the cable by suitable inductive coupling.

The resulting signals are then passed via a cable 61 to the rest of the device. Structurally, the rest of the device may be similar to that of the embodiment of Fig. 2 and the same reference numerals are used to indicate corresponding parts. The electrical circuitry within the housing 10 may be similar to that shown in Fig. 3, although there is then no direct connection to wires interconnecting input and output terminals. In this embodiment the housing may be designed so that it may be wall-mounted.

In a further modification, shown in Fig. 7, a sensor 70 of similar size to a standard fuse mounting may be provided, connected to the rest of the device by a cable 71. Again, the structure of the rest of the device may be similar to that in Fig. 6, and corresponding reference numerals are used. The sensor 70 may replace the fuse mounting in a fuse box, plug or socket thereby enabling a cost measurement to be made on the or all appliances connected to the main supply via a fuse 72 inserted in the mounting 70.

In all the above embodiments, the display 25 may be a liquid crystal display, and may provide either a real-time cost measurement or may provide an average power measurement. The switching between these two alternatives may be provided by a further control (not shown) in the housing 10 or by suitable manipulation of the extracts previously described. If the device is to provide a real-time measurement, another control may be needed for re-setting the display when desired by the user. Alternatively, disconnection from the supply (in the embodiment of Fig. 1) or opening of the switch interconnecting the terminals (e.g.in the embodiment of Fig. 3) may re-set the display.

Furthermore, a memory facility may be provided so that comparisons may be made between measurements made at different times.

Claims (11)

1. An electricity monitor having a housing input and output terminals mounted in the housing respectively for connection to an electric power source and for connection to an electric appliance, means for interconnecting the input and output terminals, means for detecting the current and voltage in the interconnection means and deriving a power measurement, means for converting the power measurement to a cost measurement, and a display in the housing for displaying the cost measurement.

2. An electricity monitor according to claim 1, wherein the housing has apertures therein associated with the output terminals for receiving pins of a plug connected to the appliance.

3. An electricity monitor according to any one of the preceding claims wherein the input terminals include pins insertable in a socket.

4. An electric power monitor according to any one of the preceding claims, wherein the conversion means is powered from the current and voltage in the - interconnection means.

5. An electricity monitor according to any one of the preceding claims, wherein the interconnection means includes a switch for disconnecting the input and output terminals.

6. An electricity monitor having a portable housing means for releasably coupling the power monitor to an electric conduction path connected to an electric power source, means for detecting the current and voltage in the conduction path and deriving a power measurement, means for converting the power measurement to a cost measurement, and a display in the housing for displaying the cost measurement.

7. An electricity monitor according to claim 6, wherein the coupling means includes pins insertable in a socket.

8. An electricity monitor according to claim 6, wherein the coupling means is an inductive pick-up.

9. An electricity monitor according to claim 6, wherein the coupling means is a sensor connected to the housing by a conductive link.

10. An electricity monitor according to any one of the preceding claims, having controls for varying the tariff rate and/or tax rate of the conversion by the converting means.

11. An electricity monitor substantially as herein described with reference to and as illustrated in Figs. 1 and 2, or Fig. 3, or Fig. 4, or Fig. 5, or Fig. 6, or Fig. 7 of the accompanying drawings.