GB2464293A

GB2464293A - An automatic switching apparatus

Info

Publication number: GB2464293A
Application number: GB0818497A
Authority: GB
Inventors: Timothy Paul Jarvis; Darren Craig Wilkinson
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-10-09
Filing date: 2008-10-09
Publication date: 2010-04-14
Also published as: WO2010041085A1; GB0818497D0

Abstract

An automatic switching apparatus (10) comprising: switch means (54) for selectively connecting or disconnecting an electrical load (58) from a mains power supply (56); trigger means (76, 86, 88) for detection of a first predetermined event; reset means (84, 36) for detection of a second predetermined event; and programmable control means (72) for actuating the switch means (54).

Description

Title: Automatic switching apparatus

Description:

This invention relates to an automatic switching apparatus.

It is often desirable to control the connection of an electrical device to an electrical power source. In particular, landlords or property owners might wish to limit the amount of electricity used to minimise expenditure and/or to safeguard the electrical safety of premises. Additionally or alternatively, the landlord or property owner might wish to ensure that conditions, e.g. the temperature, humidity etc. within the property are maintained within predetermined parameters. Moreover, it is common for electrical devices in temporarily vacated premises not to be switched off, which can be wasteful and/or uneconomic.

Automatic controllers for electrical devices are known, such as on/off switches, timer switches, (un)switched fuse units (FSUs), residual current devices (RCDs), thermostats, Passive Infrared detectors (PIRs) etc., but these known devices are generally "dumb", i.e. they lack logic, and/or are not tamperproof.

This invention aims to provide an improved automatic switching means and/or to provide a solution to one or more of the above problems.

According to the invention there is provided an automatic switching apparatus comprising: switch means for selectively connecting or disconnecting an electrical load from a mains power supply; trigger means for detection of a first predetermined event; reset means for detection of a second predetermined event; and a programmable control means for actuating the switch means.

The switch means may comprise a relay or a triac. The automatic switching means may be electrically connectable to the mains power supply and the electrical load via screw terminals arranged to receive and clamp onto the ends of the conductors of electrical cables.

The programmable control means may comprise a microcontroller. A communications port may be provided to enable the microcontroller to be programmed and/or re-programmed. The communications port may utilise an RS232 serial communications protocol, and may be connectable to physically, for example, using a stereo plug & jack or a USB plug and socket etc., or wirelessly, for example using infrared, WiFi or Bluetooth�.

The first predetermined event can be any one or more of the group comprising: an electrical current exceeding a predetermined threshold, a temperature falling outside a specified range, inactivity for a predetermined period and "normally off' periods of a programmable seven day timer.

The second predetermined event can be any one or more of the group comprising: a soft reset, a button press, an electrical current falling below a predetermined threshold, a temperature falling within a specified range, a detected activity, "normally on" periods of a programmable seven day timer.

The trigger and/or the reset means may comprise a current detection means for detecting the electrical current flowing into the electrical load. The current detection means may comprise a differential current detection means for detecting a step change in the electrical current flowing into the electrical load.

Either or both of the trigger and/or the reset means may comprise a temperature detection means, e.g. a thermocouple, a bimetallic strip or a thermistor.

Either or both of the trigger and/or the reset means may comprise an infrared detector, for example, a passive infra red motion detector. The trigger means may comprise a circuit for actuating the switch means upon non-detection of a signal from the infrared detector after a predetermined interval. The reset means may comprises a timer for resetting the switch means after a predetermined interval.

The reset means may comprise a reset switch, which could be operable using a push switch, a touch pad, or using a computer interface.

The reset means may comprise a lock to prevent/inhibit unauthorised resetting of the switch means. The lock, where provided, may comprise a key-operated lock, a combination lock and/or a password protection device/circuit and/or PIN protected computer interface.

The automatic switching means may comprise a fascia affixable to a mains power outlet back box, for example using screws. The reset switch and/or communications port may located behind the fascia and only be accessible by partially or completely removing the fascia from the back box.

Preferred embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of an automatic switching apparatus according to the invention; and Figure 2 is a schematic circuit diagram of an automatic switching apparatus according to the invention.

In Figure 1, an automatic switching apparatus 10 comprises a housing 12 that encloses an internal circuit and a fascia 14 that is affixable to a conventional mains back box 16 using screws 18. The rear of the housing 12 has two sets of screw terminals (not shown) for connecting the switching apparatus 10 to a mains power supply cable 20 and a cable 22 connected to an electrical load. It will be apparent to the skilled person that the automatic switching apparatus 10 can be wired into a mains circuit in place of a conventional switch or FSU, or in place of a ring main circuit breaker. A wire is also shown that provides an electrical connection between the switching apparatus 10 and a remote PIR sensor (not shown).

In the embodiment depicted in Figure 1, the fascia 14 is generally square-shaped and comprises a lip 11 that conceals the back box 16 when installed.

The housing 12 comprises a pressed aluminium box that attaches to the rear face of the fascia 14, which is manufactured from stainless steel, using barbed clips or self-tapping screws (not shown). The design of the housing 12 is standardised so that different housings, for example comprising different sensor types, can be affixed to a common fascia 14.

In the centre of the fascia 14, a touchpad 26 is provided for resetting the apparatus in a manner that will be described below.

The housing 12 additionally comprises a socket 36 into which a plug 38 of a communications cable 40 can be plugged. In Figure 1, the socket is a mini USB socket, although any electrical socket, e.g. a stereo jack, may be used. In use, an operator can program the automatic switching apparatus 10 by unscrewing it from the back box 16, retracting it sufficiently to expose the socket 36 and by connecting a portable computer 42 loaded with appropriate software to the socket 36 using a data cable 40.

The software loaded onto the portable computer 42 comprises a menu-type Graphical User Interface that enables a user to program various different aspects of the operation of the switch 10. The software also comprises a communications protocol, e.g. RS232, that enables the computer 42 to communicate with, program, and re-program the automatic switching apparatus 10.

In Figure 2, it can be seen that the automatic switching apparatus 10 comprises a circuit 50 having a bank of screw terminals 52 for connecting it to the mains power supply 20 and to an electrical load 22. A triac 54 is wired in series between the "mains phase" terminal 56 and the load "live" terminal 58.

Both mains phase (live) and neutral may be additionally isolated by a mechanical switch and thermal fuse. The automatic switching apparatus 10 is wired to earth 64 for safety reasons.

A transformer 66 is wired in parallel with the load live 58 and load neural terminals 62 via a resettable fuse 68. The transformer 66 is wired to an AC/DC converter 70, which is used to provide low-voltage DC power a programmable microcontroller 72. As a power saving measure, the quiescent power drain of the automatic switching device is low -the transformer 66 being rated at4lmAat9VDC.

The microcontroller 72 is wired to receive input signals from a variety of sensing devices, which shall be described in greater detail below. The microcontroller 72 is also wired (via an opto-isolator) to the gate terminal of the triac 54 and can thus control the flow of electrical current from the mains phase terminal 56 to the load live terminal 58 of the terminal block 52.

The microcontroller 72 is wired to receive input signals from an infrared sensor (not shown) that can be wired 75 to a separate terminal block 76. The infrared sensor is an off-the-shelf PIR sensor, and provides a small DC voltage to PIR terminal block 76 upon detection of the motion of a "hot body" within a predetermined zone. The provision of a PIR terminal 76 solves two problems, namely it allows segregation of mains (LNV) and low voltage (SELV) circuits, and it allows the wire to the PIR to optionally run up a wall on the surface. This is particularly advantageous as it enables the PIR to be optimally sited for the best "view" of the room, which is rarely where the switch will be.

The PIR sensor signal voltage is stepped-down by applying it to the gate terminal of a FET transistor 78, which stepped-down voltage is detected by the microcontroller as a "first event". Upon detection of a first event, i.e. movement, an internal clock within the microcontroller begins a pre-specified countdown. If no further "motion events" are detected within that period, then the microcontroller 72 removes the voltage from the gate of the triac 54 to isolate phase terminal 56 from the live load terminal 58, thereby shutting off the load.

This functionality is particularly useful because if a room is left unoccupied, say for half an hour or more, then electrical appliances within that room can be automatically switched off to conserve electricity. When a user re-enters the room, they will be detected by the PIR sensor, but the power will not be restored until a reset event occurs. The user knows that the automatic switching apparatus 10 has isolated the power, rather than there being a general electrical fault, or a power outage, because the automatic switching apparatus 10 is programmed to indicate its status audibly, by way of a buzzer and by way of a flashing LED 82.

Additionally or alternatively, the microcontroller can have an automatic time-delay reset feature, which automatically resets the switch after a predetermined period. Optionally, an automatic reset is indicated by the LED 82 flashing rapidly.

The automatic switching apparatus 10 can be reset by the user touching a touchpad 84 wired to an input of the microcontroller 72, or by a soft reset using a computer 42 connected to the communications port 36.

A variant of the above automatic switching apparatus utilises an infrared detector for detecting infrared emissions from devices, e.g. television remote controls etc. within the predetermined zone. Thus, if a user remains still for long periods of time, but remains present in the room, for example when watching television, then every time he/she operates the TV's remote control, scattered infrared light from the remote control will be detected, thereby re-starting the countdown. This arrangement reduces the likelihood of the inconvenience of electrical appliances being switched off whilst the room is still occupied by a stationary person.

The microcontroller 72 is also wired to receive signals from a temperature sensor 86 and can thus be used to control the operation of heating or cooling appliances. The automatic control apparatus 10 can be programmed to prevent a room from being overheated, for example by isolating the heating devices from the mains power supply 20 when a predetermined temperature has been reached, or to act as a frost guard, for example by turning on electrical heaters when the detected room temperature fa]ls below a predetermined temperature.

Finally, it will also be noted that the automatic switching apparatus 10 comprises a current sensor 88 wired to monitor the current draw of the electrical load 12. The microcontroller 72 can be programmed to isolate the load live terminal 58 from the mains phase terminal 56 upon detection of a current exceeding a predetermined current. The predetermined current may be the upper limit that the buildings wiring can withstand (e.g. 13A), or it might be much lower (e.g. IA), for example, to discourage the use of multiple plug mains adapters etc, which can overload mains sockets. Alternatively the unit can be programmed to isolate the load if a step change in the load current exceeds a predetermined delta value. For example many low current devices may be plugged in without causing isolation, but a single high current device being plugged in will cause an alarm followed shortly by isolation of all plugged in devices if the high current device is not swiftly unplugged.

Any one or more of the above functions can be used simultaneously or in isolation. In one example, the automatic switching apparatus 10 can be programmed to control the temperature of a room and to guard against over currents with all other functions disabled. In another example, the automatic switching apparatus 10 might be programmed to control the power to an electrical device based on activity/inactivity within a predetermined zone, and to monitor for over currents, but instead of shutting off the power in such a case, to alert users to over currents using the buzzer 80 and LED 82. It will be appreciated that the use of a microcontroller and a computer user interface enables the automatic switching apparatus to operate in a variety of modes.

Nevertheless, it is envisaged that the microcontroller will be pre-loaded with a menu of default operating modes, which can be used "out of the box", but which can also be customised using the computer 42/communications port 30.

Importantly, since the microcontroller will need to be used continuously for extended periods of time (moths or years) without user intervention, it is programmed to self-reset periodically andfor upon detection of a lock-up.

The microcontroller is protected using a PIN code device, which may comprise hardware buttons (not shown), or which may need to be input by a user when connecting thereto using the communications port 36. A default PIN is provided for first installation and setup, although the PIN can be changed for security purposes.

The invention is not limited to details of the foregoing embodiments, for

example:

Where the automatic switching device 10 comprises an infrared detector 26, the computer 42 can communicate with the internal circuit using IR communications protocol. Additionally or alternatively, the control circuit could comprise a radio transceiver, which could allow it to communicate with the computer using a radio communications protocol, e.g. WLAN, Bluetooth� etc. An advantage of providing wireless programming capability is that the switching unit 10 does not necessarily need to be unscrewed from the back box 16 to enable it to be programmed, re-programmed or reset.

The PIR, where provided, may connect wirelessly to the switching apparatus obviating the need for additional wiring.

Claims

Claims: 1. An automatic switching apparatus comprising: switch means for selectively connecting or disconnecting an electrical load from a mains power supply; trigger means for detection of a first predetermined event; reset means for detection of a second predetermined event; and programmable control means for actuating the switch means.
2. An automatic switching apparatus as claimed in claim 1, wherein the switch means comprises a triac.
3. An automatic switching apparatus as claimed in claim I or claim 2, wherein the automatic switching means is electrically connectable to the mains power supply and to the electrical load via screw terminals.
4. An automatic switching apparatus as claimed in any of claims 1 to 3, wherein the programmable control means comprises a microcontroller.
5. An automatic switching apparatus as claimed in claim 4, further comprising a communications port to enable the microcontroller to be programmed and/or re-programmed.
6. An automatic switching apparatus as claimed in any preceding claim, wherein the first predetermined event is any one or more of the group comprising: an electrical current exceeding a predetermined threshold, a temperature falling outside a specified range, inactivity for a predetermined period, and preset off period' of a seven day timer.
7. An automatic switching apparatus as claimed in any preceding claim 1, wherein the second predetermined event is any one or more of the group comprising: a soft reset, a button press, an electrical current falling below a predetermined threshold, a temperature falling within a specified range, a detected activity, and preset on period' of a seven day timer.
8. An automatic switching apparatus as claimed in any preceding claim, wherein the trigger and/or the reset means comprises a current detection means including a step-change of delta-current detection means.
9. An automatic switching apparatus as claimed in any preceding claim, wherein the trigger and/or the reset means comprises a temperature detection means.
1O.An automatic switching apparatus as claimed in any preceding claim, wherein the trigger and/or the reset means comprises an infrared detector.
11.An automatic switching apparatus as claimed in claim 10, wherein the infrared detector comprises a passive infra red motion detector.
12.An automatic switching apparatus as claimed in any preceding claim, wherein the trigger comprises a circuit for actuating the switch means upon non-detection of a first event after a predetermined interval.
13.An automatic switching apparatus as claimed in any preceding claim, wherein the reset means comprises any one or more of the group comprising: a timer for resetting the switch means after a predetermined interval; a reset switch; a push switch; a touch pad; and a computer interface.
14.An automatic switching apparatus as claimed in any preceding claim, wherein the reset means comprises a lock.
15.An automatic switching apparatus as claimed in any preceding claim, further comprising a fascia affixable to a mains power outlet back box.
16.An automatic switching apparatus as claimed in claim 15, wherein the reset switch and/or communications port are located behind the fascia and are only be accessible by partially or completely removing the fascia from the back box.
17.An automatic switching apparatus substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.