GB2484658A

GB2484658A - Energy saving electrical switch

Info

Publication number: GB2484658A
Application number: GB1017290.6A
Authority: GB
Inventors: John Halfpenny; Giles Hutchison
Original assignee: ENERGY REDUCING PRODUCTS Ltd
Current assignee: ENERGY REDUCING PRODUCTS Ltd
Priority date: 2010-10-13
Filing date: 2010-10-13
Publication date: 2012-04-25
Anticipated expiration: 2030-10-13
Also published as: GB201017290D0; GB2484658B

Abstract

An electrical switch comprises an electrical inlet 1 for supplying electrical energy to an electrical outlet 5 and a controller 13 including means 3 for measuring the energy consumption of an appliance attached to the outlet over a pre-set period of time; a light level sensor 12; and an electrical switch 4 to connect or disconnect the electrical outlet from the inlet. The controller can connect or disconnect the electrical outlet according to the operating mode of the attached appliance, determined by detecting a change in the measured level of energy consumed by the appliance relative to one or more thresholds, and according to the measured light level and the operating mode. The controller may also use measured light levels to determine working days or nights and, in conjunction with the determined operating modes of the appliance, determine regular or extended periods of time where an attached appliance is not used; predict forthcoming periods of likely inactivity such as weekends and bank-holidays; and operate the switch to disconnect the appliance for the duration of the likely period of inactivity. There may be plural outlets 6 that are individually connected or disconnected and in different combinations. The controller may detect patterns of use including regular or extended periods of an appliance being in a standby mode such as week-ends and holidays, predict likely such inactivity periods and connect/disconnect an appliance accordingly.

Description

Title: Improved Electrical switching apparatus

Field of the invention

This invention relates to apparatus for determining the operating state of an attached electrical appliance by measuring the energy that it consumes and in conjunction with a light level sensor for switching power to the appliance such that if the appliance is not in use it can be automatically turned off overnight and over weekend periods, thus saving energy consumption.

Background of the invention

With rising electrical energy costs and growing awareness of the environmental damage caused by unnecessary energy consumption, consumers wish to reduce the amount of electrical energy they are using. Many electrical appliances continue to use energy even when they are in their stand-by' state and consumers want to eliminate this completely wasted energy use.

There are disclosed instances of consumed current or power energy being measured as an indication of the operating state of an appliance, as disclosed in KR2002002463 1, GB2438655. GB 1004429.5 also discloses the use of measured energy being used to more accurately determine the operating state of an attached appliance. GB 1004429.5 also discloses the optional use of an additional light sensor to enable an attached appliance to be turned off at night if and when it is not in use and to be turned back on again when it becomes light again, the effect of which is to eliminate stand-by energy being used by an appliance overnight.

Using measured energy, power or cunent to detect the operating state of an attached appliance and a light sensor to detect light and dark periods corresponding to days and night, it is also possible to determine patterns of appliance use -such as the attached appliance being in stand-by over two daylight periods signifying a weekend period, when the appliance is not likely to be used and therefore to be in a stand-by' state.

By determining such patterns of use, and counting days and nights it is possible to predict and determine future weekend periods and turn off the power to the attached appliance for the duration of those periods -thus achieving further energy savings over and above those that can be achieved by disconnecting power to the attached appliance at night.

This invention describes the process required to achieve this further saving.

Summary of the invention

As disclosed in KR20020024631, GB2438655 and GB 1004429.5 it is possible to measure the cunent, power or energy being used by an attached electrical appliance and from this to determine the operating state of the appliance, including if it is in a stand-by' state. If, as also disclosed in GB 1004429.5 ambient light levels are measured, it is possible to switch an attached electrical appliance off at night if it has entered a stand-by' state and to turn it back on again in the morning, thus automatically eliminating wasted energy at times outside of a working day without the user having to make any kind of action.

In addition to switching power off overnight, it is possible to use measured light levels to determine if it is night or day and optionally to use an internal timer to distinguish between short periods of changed light level such as shadows, clouds, brief periods of light and longer periods of changed light so that days and nights can be reliably detected.

In a typical work environment, a day may be a period of natural light or artificial light. If the apparatus is operated in a typical work environment such as an office or warehouse and if it is determined that there have been two or more days where the attached appliance did not leave its stand-by' state, the apparatus can determine that a weekend period has just passed. The apparatus may then count 5 more days after this event and automatically turn the power to the attached appliance off over the following two days and nights -thus leaving the attached appliance switched off over the weekend period, significantly decreasing the amount of time the attached appliance spends in stand-by' mode each week.

Optionally, the apparatus may improve predictions of forthcoming weekends or similar periods by validating that the attached appliance leaving its stand-by' state for all or some of the 5 days after detecting a weekend before predictively switching off the attached appliance the following weekend.

Representative energy measurement, light measurement & switching apparatus With reference to figure 3, power from the mains supply enters the unit from plug (1).

Plug (1) may be integral with the case (13) or on a trailing wire connected from the case. Either the power or neutral, or both of these power connections from the mains supply may be switched by (4) prior to connection to (5) or (6). The appliance(s) plug into socket (5) or (6). Output socket(s) (5) or (6) may be integral to the case (13), or on a trailing cable from case.

The unit that implements the invention includes a controller (8), switch or switches (4), current measurement circuit (3) (7), an internal power supply (14) for these elements and a variable number of light level sensors and controls (9) (10) (11) (12).

The power supply (14) may be implemented using resistor, capacitor, rectifier circuit(s), or using a transformer and rectifier. The power supply may provide one or more voltage rails, and one or more of these voltage rails may be switchable, so that the power consumed by the unit may be reduced when these voltages are not required.

Representative embodiments of these elements are described in the following sections.

Measuring energy consumed by an attached appliance Measuring the energy consumed by an appliance may be performed by a controller as follows: 1. With reference to figure 3, the voltage drop across a low resistance sense resistor (3) is amplified (7) and fed to a controller with integral or external Analogue to Digital converter. A current sense transformer may be used instead of Sense resistor (3) to monitor the current consumed by the appliance plugged into (5) or (6) by passing one of the two conductors at (2) through the current transformer. The voltage level is sampled regularly at a frequency which is greater than the AC electricity supply frequency. This allows the controller to sample the instantaneous current being drawn by the appliance several times during each AC cycle.

2. The AC mains supply voltage is attenuated (16) and fed to the controller (17) so that the controller can determine the magnitude of the AC mains voltage waveform at any time.

3. The controller has timers to allow it to accurately measure time intervals of units of Milliseconds to hundreds of Seconds.

4. With reference to figure 1, over a pre-set time (1) which may vary from about 2OmS to thUS, the controller repeatedly samples the instantaneous current and multiplies this by the instantaneous voltage to give instantaneous power (8).

The instantaneous power value is added to a sum of all the previous values to form an integral (7) of the power readings which represents the energy consumed (4) during the pre-set sampling time (1).

5. With reference to figure 2, the integration process in step 4 above is continuously repeated (1), enabling the energy consumption of the attached appliance to be known (7), (8), (9) and the operating state to be determined.

Measuring tight levels With reference to figure 3, the controller (8) will monitor light level sensor(s) integral with the case (11), or sensor(s) external to the case (12). The light level may be monitored by a photocell, photodiode, phototransistor or light dependent resistor interfaced to the controller The controller may also optionally monitor an override switch (9) to manually override the controller to open or close switch (4). The unit may also control one or more LED's to indicate the status of the unit.

Determining operating state of connected appliance Many appliances have multiple operating states, which are characterised by different levels of energy consumption. For example a laser printer may have stand-by', idle' and printing' modes, with corresponding energy consumption levels. In some applications it may be necessary to determine if the appliance is in stand-by mode or not, and a single consumed energy level threshold may be selected, above which the appliance is in an active' state and below \vhich the appliance is in stand-by' state.

The measured energy consumption level may be compared with this threshold to determine the operating state of the appliance. If it is desired to determine multiple operating states, multiple thresholds may be implanted.

In some applications, single or multiple thresholds may be pre-set to fixed values, but the utility of the switching apparatus may be considerably improved by making the thresholds variable and adapting them to the attached appliance.

For many appliances, the various energy consumption levels colTesponding to operating modes are a multiple of the lowest energy consumption level corresponding to an idle' or stand-by' state, so energy consumption thresholds may be calculated adaptively as a multiple of this lowest energy consumption level.

Switching power to connected appliance With reference to figure 3, depending on the operating state of the appliance as deduced by its energy consumption and energy switching thresholds, the controller may connect or disconnect power to electrical outlet(s) using switching means (4).

Switch (4) may be a Relay or TRIAC with associated control circuitry. Switch (4) is turned on and off under control (15) of the controller.

The switching arrangements could be such that that there is a plurality of electrical outlets connected and disconnected by one switch, groups of electrical outlets which can be as a group connected and disconnected by individual switches or a plurality of electrical outlets each connected and disconnected by individual switches.

Optionally, the controller may monitor of the phase and zero cross over point of the mains voltage to assist with the turning on and off of the switch (4).

Using a light level sensor (12), the controller may not switch an attached appliance off, even if it was deduced to be in an idle or stand-by state unless it was dark as well.

Upon resumption of light -for example in the moming or when lights are tumed on, the controller may switch the attached appliance back on again -thus obviating the user from any intervention to turn the appliance off or on.

In addition to switching power off overnight, the controller may optionally use the light sensor (12) to determine if it is night or day and may optionally use an internal timer in the controller (8) to distinguish between short periods of changed light level such as shadows, clouds, brief periods of light and longer periods of changed light so that days and nights can be reliably detected. The controller may optionally use the rate of change of light level to further improve the reliability of days and nights or to differentiate between periods of artificial light -which have much faster rates of change of brightness, from natural daylight -which has a slower rate of change of brightness.

In a typical work environment, a day may be a period of natural light or artificial light. The controller may furthermore determine if the attached appliance has left its stand-by' or other low-power state during the course of each measured day period.

If the apparatus is operated in a typical work environment such as an office or warehouse and if the controller detects that there have been two or more days where the attached appliance did not leave its stand-by' state, it may deduce that a weekend period has just passed.

The controller may then count 5 more full days after this event and turn the power to the attached appliance off over the following two days -thus leaving the attached appliance switched off each weekend, significantly decreasing the amount of time the attached appliance spends in stand-by' mode each week.

Claims

Claims An electrical apparatus comprising: an electrical outlet; an electrical inlet for supplying electrical energy to the electrical outlet; and a controller, the controller including: a means for measuring energy consumption drawn from the electrical outlet over a pre-set period of time; an electrical switching means for connecting or disconnecting the electrical outlet to the electrical inlet; a power supply for the controller, drawing electrical power from the electrical inlet; and a means of measuring ambient light levels.wherein the controller may: a) determine the operating mode of the attached appliance when the controller detects a prescribed change in the measured level of energy consumed by the appliance relative to one or more switching energy thresholds; b) determine whether it is in a daylight period or night time period by reference to measured light levels; c) connect or disconnect the electrical outlet to the electrical inlet according to the determined operating mode and whether it is a daylight or night-time period; d) detect if the attached appliance has not left its low-power or stand-by' operating mode for one or more daylight or night-time periods, and so determine that it is a weekend or similar non-working hours period; and e) connect or disconnect the electrical outlet to the electrical inlet according to predictions of future weekend or non-working hours periods based on the determined weekend or similar non-working hours period.
2. The electrical switching apparatus as claimed in claim 1, wherein there may be a plurality of electrical outlets connected in parallel with each other and all connected or disconnected to the electrical inlet by the switching means as claimed in claim 1.
3. The electrical switching apparatus as claimed in claim 1, wherein there may be a plurality of electrical outlets with a separate switching means for each one or groups of outlets and the controller may connect or disconnect each individual or group of electrical outlet(s) from the electrical inlet.
4. The electrical switching apparatus as claimed in claim 1 and claim 3, wherein the controller may arbitrarily connect or disconnect any combination of electrical outlets from the electrical inlet.
5. The electrical switching apparatus as claimed in claiml and claim 3 and claim 4, wherein the controller may connect or disconnect different combinations of electrical outlets according to the operating state of the attached appliance as determined by the controller.
6. The power distribution apparatus as claimed in claiml, wherein the controller may return the switching energy threshold to its pre-set value in the event of: a. An interruption of the power supply to the controller and/or the electrical inlet; and/or b. Operation of the switching means such that one or more of the electrical outlets is disconnected from the electrical inlet.
7. The power distribution apparatus as claimed in claim 1, wherein one or more light level sensors may additionally be connected to the controller and wherein the controller may use measured external light levels to operate the switching means to re-connect the electrical outlet to the electrical inlet independently of the measured level of energy consumed.
8. The power distribution apparatus as claimed in claim 2, wherein one or more light level sensors may additionally be connected to the controller and wherein the controller may use measured external light levels to operate the switching means to re-connect the electrical outlets to the electrical inlet independently of the measured level of energy consumed.
9. The power distribution apparatus as claimed in claim 1, wherein one or more light sensors enable the controller to determine light and dark periods corresponding to day and night periods and in conjunction with the controllers ability to detect the operating mode of an attached appliance as also claimed in claim 1, detect patterns of use where the attached appliance has not left it's stand-by', inactive or other lower energy operating state during each day or night.
10. The power distribution apparatus as claimed in claim 1 and in claim 19, wherein the controller may examine patterns of use to identify regular or extended periods of time where an attached appliance is not used, such as weekends, bank-holidays etc.
11. The power distribution apparatus as claimed in claims 1, 9 and 10, wherein the controller may predict forthcoming periods of likely inactivity such as weekends and bank-holidays and operate the switching means to disconnect the attached appliance for the duration of the likely period of inactivity.
12. The power distribution apparatus as claimed in claim 2, wherein one or more light sensors enable the controller to determine light and dark periods corresponding to day and night periods and in conjunction with the controllers ability to detect the operating mode of an attached appliance as also claimed in claim 1, detect patterns of use where the attached appliance has not left it's stand-by', inactive or other lower energy operating state during each day or night.
13. The power distribution apparatus as claimed in claim 2 and in claim 12, wherein the controller may examine patterns of use to identify regular or extended periods of time where an attached appliance is not used, such as weekends, bank-holidays etc.
14. The power distribution apparatus as claimed in claims 2, 12 and 13, wherein the controller may predict forthcoming periods of likely inactivity such as weekends and bank-holidays and operate the switching means to disconnect the attached appliance for the duration of the likely period of inactivity.