POWER LEVEL INDICATOR FOR A PLUG OR A SOCKET
Field of the Invention
The invention relates to apparatus for a plug or a socket comprising a user operable switch having a power level indicator. The invention also relates to a plug having a power level indicator.
Background
Electrical power is becoming increasingly expensive. Knowledge of power consumption enables users of appliances to reduce their consumption. For example, if a user knows that an appliance uses a non-negligible amount of power when on standby, the user may unplug the appliance or, if the socket is of a type that includes a switch, may switch off supply of power from the socket. If a user knows that an appliance has a high power consumption when used, the user may change their behaviour; for example the user may choose to reduce use of that appliance, such as by drying laundry outdoors rather than using a tumble drier.
Devices that display power usage information are known. Such devices locate between a plug of an appliance and a socket, and comprise a respective plug for location in the socket and a respective socket to receive a plug of the appliance, as well as a display for displaying power usage information. Such devices are considered too costly for use continuously with multiple appliances.
A known patent publication, number CN201408885Y, discloses a plug socket having an electrical energy display screen. A problem with such plug sockets is that a casing of the socket must be different to conventional casings to include such a screen.
Summary of the Invention
According to a first aspect of the present invention, there is provided apparatus for a plug or socket as defined in claim 1. Advantageously, since apertures in casings of sockets for rocker switches are generally rectangular and have the same or similar height and the same or similar widths, the apparatus, or different versions with only slightly different switches, can be used with different casings. Thus, such switches can be used with casings of different manufacturers. The casings need not be modified to accommodate a power level indicator.
According to a second aspect of the present invention, there is provided a plug as defined in claim 11. The power level indicator enables power usage level of the appliance to be understood by the user, regardless of whether a socket to which the plug is connected has a power usage indicator.
Brief Description of Figures
For better understanding of the present invention, embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 is a front view of a socket having a switch in accordance with an embodiment of the invention; Figure 2 is a diagram of control circuitry in accordance with the embodiment; Figure 3 is a flow diagram shows steps that occur at a controller in accordance with the embodiment; Figure 4 is a diagram of alternative control circuitry in accordance with an alternative embodiment; and Figure 5 is a view of a plug in accordance with another embodiment.
Detailed Description of Embodiments
Like reference numerals are used to denote like parts throughout.
Embodiments of the invention relate to apparatus for an electrical power socket. Referring to Figure 1, a double electrical wall socket 10 includes a casing 12 (also known as an outer plate), two female connector portions 14 and, for each female connector portion 14, a switch 16. The switches 16 are the same and each has an integrated power level indicator 18 viewable by the user. The casing 12 has a height indicated at C-C and a width indicated at D-D. Embodiments are not limited to use with a wall socket. Also, embodiments are not limited to use with a double socket; embodiments may be used with a single socket or a device having multiple sockets. The casing 12 of the double wall socket 10 typically is formed with two apertures of the same shape, each to receive a respective one of the switches 16 and each of a height, indicated at A-A, and first width, indicated at B-B. The height is typically about 22mm to 25mm and the first width is about 9mm to 12mm. Single sockets typically have a single aperture of the same height and a second width typically of about 10mm to 15mm.
The casing 12 is formed of rigid material, for example hard plastic or metal. The female connector portion 14 includes spaced holes arranged to receive a corresponding male portion of a plug in accordance with the BS1363 standard. Bolts 19 fix the casing 12 to a back box via respective holes in the casing 12.
The socket 10 includes conventional wiring and components in the back box enabling an appliance whose plug is connected in the respective connector portion 14 to draw electrical power. The switches 16 are mechanical rocker switches and each is operable in a push action by the user to toggle between enabling power to be drawn by a connected appliance through a plug connected in the respective connector portion 14 and preventing power being so drawn. In addition, the socket 10 includes control circuitry for monitoring the power drawn by a connected appliance and for controlling the power level indicator 18 so as to provide for the user an indication of a level of drawn power.
The power level indicator 18 comprises a light emitter 30 and a light transmitting piece, for example of hard transparent plastic, over the light emitter 30. The light transmitting piece provides part or all of the surface of the switch 16 that can be pressed. The light emitter comprises light emitting diodes (LEDs) configured to emit different colours, for example green, orange and red light. Embodiments are not limited to the light emitter being of any particular type, provided emitted light can be seen at the switch 16 by the user and a plurality of colours of light can be emitted for indicating to the user different power usage levels.
The light emitter 30 is preferably integrated into the switch 16, in that the LEDs are mounted to a back side of the switch 16. For example, the LEDS may be mounted on a base, the base and the back side of the switch being configured to clip together. In variant embodiments, the light emitter 30 sits behind or behind the casing 12 to a side of the switch, and may not be physically connected to the switch; in this case the switch 16 is nevertheless configured so that emitted light is visible to the user through the light transmitting piece.
In other variant embodiments, the light transmitting piece is not part of the surface portion of switch 16 that is pressable. For example, in a rocker switch conventionally used in wall sockets in the UK, an end portion of the switch is coloured red. The red portion is visible when the rocker switch is in an on state permitting power to be drawn from the socket, and is hidden when the rocker switch is in an off state preventing drawing of power. The portion of the switch conventionally coloured red may be replaced with a light transmitting piece through which emitted light can be seen. In variant switch designs in which a part of the switch is hidden when the switch is in an off-state, the light transmitting piece may be located so as to be hidden when the switch is in the off state and visible to the user when the switch 16 is in the on state.
Referring to Figure 2, the control circuitry, which is behind the casing 12 and whose general location is indicated in Figure 1 at 20 using broken lines, includes a current sensor 24, a memory 25 and a controller 28, all operatively connected with a bus. In addition, the control circuitry 20 is coupled to the conventional wiring to draw power to power the control circuitry 20. The current sensor 24 is connected to the conventional wiring and/or components so as to provide to the controller 28 information indicative of the current drawn by a connected appliance. The controller 28 stores the received information in the memory 25. The controller 28 is also operatively connected to the light emitter, to control operation thereof.
Power used is proportional to the square root of current drawn, and so the controller 28 can use the current as a proxy for power usage. The controller 28 is configured to determine the average current used by the appliance based on the stored information over a predetermined preceding period. The period may be n seconds, where n is between 1 and 10, for example. The period is not limited to this and may be longer or shorter; the controller 28 may in some embodiments determine the current on a per waveform basis. The controller 28 may delete from the memory 25 current information that occurred greater than a predetermined time ago, for example more than 10 seconds ago.
The controller 20 is electrically coupled to the light emitter and configured to control the light emitter 30 so the power level indicator 18 is a different colour dependent on power usage level. Although the functionality is implemented algorithmically, the memory 25 can be considered to store a correspondence table mapping ranges of average current used against control instructions for the light emitter 30. By way of example, in a typical 13 amp UK socket of about 230v, the controller 20 is configured to control the light emitter 30 dependent on power usage level in accordance with thresholds in the following example table: Average current Control information for power level indicator Less than 3 amps Green Greater than 3 and less than 10 amps Orange Greater than 10 amps Red In variant embodiments, the thresholds of the ranges can be different. hi particular, the thresholds may be different where the voltage provided to a socket is different anclior the maximum current that may be drawn is different In variant embodiments, the number of power usage levels indicated to the user need not be three as in the example. The number is greater than two and typically not more than five. In this case the controller 28 and the light emitter is configured to emit a corresponding number of colours distinguishable by the user and which the user understands as corresponding to a particular power usage level. Information on correspondence between particular colours and power usage levels may be separately provided in instructions for the user. In variant embodiments, a colour is not determined using thresholds, but instead the determined current maps to a continuous range of colours on a spectrum.
The height and width of the apertures in the casing 12 are generally the same or similar for double sockets and the same or similar for single sockets across different designs of double and single sockets, respectively, made by different manufacturers. This enables a switch with the integrated power level indicator having corresponding height and width to be used across different designs of casing 12. In particular, two shapes of switch 16 shaped to fit in apertures at the lower end of the range of heights and widths may be manufactured and used with a majority of available casings.
Referring to Figure 3, in operation the controller 28 receives the information on instantaneous current from the current sensor 24 at step A. The controller 24 stores the received information at step B in the memory 25. The controller 24 then determines at step C the average current over a preceding time period. At step D, the controller 24 uses the correspondence table to determine a control instruction corresponding to the determined average current by comparison with the thresholds. The controller 24 then controls the light emitter 30 using the control instruction at step E. The controller 24 is configured to perform steps A to E periodically, for example at intervals of every m seconds where m is between 1 and 10.
Referring to Figure 4, in another embodiment, instead of monitoring current and assessing power usage using current, control circuitry 20a is modified relative to the control circuitry 20 to calculate a value for power usage. To this end, the control circuitry 20a additionally includes a voltage sensor 22 connected to the conventional wiring and/or components so as to provide to the modified controller 28a information indicative of the voltage across the plug. The controller 28a is configured to store the voltage information in the memory 25 as well as the current information. The controller 28a is configured to determine average power over the preceding time period using the following equation: Pavg = Vans Irms COO Where Pavg is the average power, Vim is the root mean square of the measured voltage, lims is the root mean square of the measured current, and cos4) is the phase difference between the voltage and the current.
In this embodiment, the correspondence table is modified to include power usage threshold values relevant to average power usage rather than to current.
In operation, at a modified step A, the controller 24a receives the current information and also the voltage information. In a modified step B, the controller 24a stores the received current and voltage information. In a modified step C, the controller determines the average power usage over the preceding period. In a modified step D, the controller 24a determines a control instruction for the light emitter using the correspondence table. Like at step E, the controller 24 then controls the light emitter 30 based on the control information. The controller 24 is configured to perform steps A to E (as modified) periodically.
Embodiments are not limited to any particular way that the power usage, or a proxy therefor, is calculated or estimated. Various alternative ways may be known to persons skilled in the art.
The sockets 10 are to receive plugs in accordance with the BS1363 standard, which are common in the UK, Ireland, Malaysia and Singapore, for example. Embodiments are not limited to sockets for plugs according to this standard.
In alternative embodiments, the switch 16 and the control circuitry 20, 20a is not for location in a socket. Instead, a plug is adapted to include the switch 16 having the integrated power level indicator and the control circuitry 20, 20a is located in the plug.
Referring to Figure 5, in alternative embodiments instead of the power level indicator being integrated into a switch, the power level indicator 54 is located in a casing 50 of a plug 52. In this case, the control circuitry 20, 20a is located within the plug.
Herein the controller may be in the form of a microcontroller. Such a microcontroiler includes a processing unit, a memory unit, input/output interfaces and a clock. all operatively connected by a bus. A computer program comprising computer program instructions in the memory unit is executed by the processing unit to provide the microcontroller with the functionality ascribed to the controller herein. In variant embodiments, the control instructions may be implemented in hardware or in a combination of software and hardware.
As the skilled person will appreciate, various modifications not already described may be made to the embodiments described above. For example, some electrical sockets, particularly those branded as "smart", may have an illuminating portion when on, that is, when power can be drawn from the socket. In this case, in accordance with an embodiment the light emitter that causes the illumination and control circuitry in the socket are adapted so that the control circuitry causes the colour of the illumination to indicate the power usage level of a connected appliance Such illuminating portions may be associated with a switch. Notably, such smart switches may not have the rocker switch that is conventionally used in electrical sockets in the United Kingdom. Some such smart switches may have a "soft" switch instead of the rocker switch; for example they may be in the form of a depressible button or a touch sensitive switch. The illuminating portion may be part of such a switch.
Unless otherwise indicated, all individual features and/or steps of all embodiments described herein are disclosed in isolation and any combination of two or more such features is also disclosed, to the extent that such features or steps or combinations of features and/or steps are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art. This is regardless of whether such features or steps or combinations of features and/or steps solve any problems disclosed herein.