FIELD OF INVENTION

This invention relates broadly to switching of electricity in buildings or installations and more specifically to a system and method for providing both course building control of electricity and fine load/appliance level control of electricity within the building.

BACKGROUND OF INVENTION

The Applicant has noted that some buildings or installations have a master electrical switch to turn the electricity supply to that building or installation on or off. During periods of inactivity (e.g., at night) or maintenance (e.g., electrical repair work), the switch may be turned off by an operator. If an occupant of the building wishes to work in the building, and finds the power turned off, he may endeavour to turn it back on. This could cause danger to maintenance personnel working on the electrical system or could merely cause inessential devices to be powered up, thus being wasteful. Further, this master electrical switch controls electricity supply to the whole building, and cannot provide appliance-level or individual load-level control.

The Applicant is also aware of so-called "smart" devices and "connected" houses in which appliances can be controlled remotely. However, there are many "dumb" appliances which are not subject to remote control, other than by interrupting their supply of electricity at a switchboard. The Applicant believes that it would be costly and wasteful to replace an otherwise working "dumb" appliance with a smart appliance merely for the sake of remote control. Accordingly, the Applicant desires a system and method that permits both course control of a whole building or installations and fine control of individual loads or appliances, with the appliances themselves not requiring replacement or modification.

SUMMARY OF INVENTION

Accordingly, the invention provides an electrical switching system for a building or installation having a master electricity input connected to a distribution unit which splits the master electricity input into a plurality of electricity lines, the electrical switching system including: an access control subsystem provided, or configured to be provided, upstream of the distribution unit at the master electricity input, the access control subsystem including: a master switch configured to connect or disconnect the master electricity input from the distribution unit; a user input arrangement operable to receive a coded input from a user; and a master controller operable to compare the received coded input against at least one correct code and, in response to the coded user input matching a correct code, to open or close the master switch in accordance with the received coded input; and a plurality of slave control subsystems, each slave control subsystem provided, or configured to be provided, downstream of the distribution unit at one of the split electricity lines, each slave control subsystem including: a slave switch configured to connect or disconnect the split electricity line from the distribution unit; a sensor operable to receive an external signal; and a slave controller operable to open or close the slave switch in response to the received external signal, the electrical switching system thus providing course control of the whole building or installation by means of the master control subsystem and providing fine control of a plurality of the electricity lines of the building or installation by means of the slave control subsystems.

The term "distribution unit" includes an electrical wiring or splitter where at least one electrical input is split into two or more electrical outputs. A common example of this is a distribution board or switchboard which is common in most buildings or installations and which in many regions is required by law.

The user input arrangement may be a keypad. The coded input may be a PIN code or password. The Applicant envisages that only a few authorised users, e.g., administrators, will be provided with the correct code. Accordingly, the electricity supply to the whole building or installation may only be controlled by the few authorised users.

The plurality of slave control subsystems may include plural sensor types. For example, one slave control subsystem may include a sensor type which is different from that of a different slave control subsystem. Instead, or in addition, one of the slave control subsystems may include plural sensors types.

The sensor may be an infrared sensor responsive to an infrared signal. The infrared signal may be provided by a remote control (similar to those used for televisions).

The sensor may be an acoustic sensor (e.g., a microphone) responsive to sound, e.g., speaking or sound generated by movement.

Each slave control subsystem may control a particular load or appliance which is powered by the split electricity line. The slave control subsystems may be independent of each other. The slave control subsystems may be dependent on the access control subsystem.

In one embodiment, the electrical switching system may be primarily hardware-based. The access control subsystem may be embodied, at least partially, by a PCB (Printed Circuit Board) which may comprise discrete electronic components. The slave control subsystem may be embodied, at least partially, by a PCB (Printed Circuit Board) which may comprise electronic components. The access control and slave control subsystems may be contained on separate PCBs.

In a different embodiment, the electrical switching system may be primarily software- based. The access control subsystem and/or the slave control subsystems may be software modules which are executable by a computer processor.

The invention extends to a method of switching electricity in a building or installation having a master electricity input connected to a distribution unit which splits the master electricity input into a plurality of electricity lines, the method including:

providing an access control subsystem upstream of the distribution unit at the master electricity input, the access control subsystem being configured to: connect or disconnect, by a master switch, the master electricity input from the distribution unit; receive, via a user input arrangement, a coded input from a user; and compare, by a master controller, the received coded input against at least one correct code and, in response to the coded user input matching a correct code, to open or close the master switch in accordance with the received coded input; and providing a plurality of slave control subsystems, each slave control subsystem provided, or configured to be provided, downstream of the distribution unit at one of the split electricity lines, each slave control subsystem being configured to: connect or disconnect, by a slave switch, the split electricity line from the distribution unit; receive, via a sensor, an external signal from a user; and open or close, by a slave controller, the slave switch in response to the received external signal, the method thus providing course control of the whole building or installation by means of the master control subsystem and providing fine control of a plurality of the electricity lines of the building or installation by means of the slave control subsystems.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings:

FIG. 1 shows a PRIOR ART setup of a distribution unit or switchboard;

FIG. 2 shows a schematic view of an electrical switching system for a building or installation, in accordance with the invention;

FIG. 3 shows a schematic view of an access control subsystem of FIG. 2;

FIG. 4 shows a schematic view of a slave control subsystem of FIG. 2;

FIG. 5 shows a schematic circuit diagram of the access control subsystem of FIG.

2;

FIG. 6 shows a schematic circuit diagram of the access control subsystem of FIG.

5 in another state;

FIG. 7 shows a schematic circuit diagram of the access control subsystem of FIG.

5 in another state;

FIG. 8 shows a schematic circuit diagram of an infra-red embodiment of the slave control subsystem of FIG. 3; FIG. 9 shows a schematic circuit diagram of the slave control subsystem of FIG. 8 in another state;

FIG. 10 shows a schematic circuit diagram of an acoustic embodiment of the slave control subsystem of FIG. 3;

FIG. 11 shows a schematic circuit diagram of the electrical switching system of FIG.

2;

FIG. 12 shows a schematic view of a PCB of the access control subsystem of FIG.

3;

FIG. 13 shows a schematic view of a layout of the PCB of FIG. 12;

FIG. 14 shows a schematic view of a PCB of an infra-red embodiment of the slave control subsystem of FIG. 4;

FIG. 15 shows a schematic view of a layout of the PCB of FIG. 14;

FIG. 16 shows a schematic view of a PCB of an acoustic embodiment of the slave control subsystem of FIG. 4; and

FIG. 17 shows a schematic view of a layout of the PCB of FIG. 16.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiment described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof. FIG. 1 illustrates a PRIOR ART switchboard 10 (which is a simple example of a distribution unit). A master electricity input 12 is connected to the switchboard 10 which splits the master electricity input 12 into a plurality of electricity lines 14. The electricity lines 14 are connected to individual loads/appliances 16 or to a group of loads/appliances. The switchboard 10 may include a series of conventional switches and circuit breakers. A voltage carried by the master electricity input 12 and electricity lines 14 is domestic single-phase 1 10-120 V or 220-240 V AC, 50-60 Hz, but in other examples it could be higher voltage or three-phase, e.g., for more industrial-type switchboards or distribution units.

FIG. 2 illustrates an electrical switching system 100 for a building or installation, in accordance with the invention. The electrical switching system 100 comprises two types of subsystems, namely an access control subsystem 1 10 and a plurality of slave control subsystems 120. The access control subsystem 1 10 is provided electrically upstream of the switchboard 10 in-line with the master electricity input 12 (with a short section of master electricity input after the access control system being designated by reference numeral 12.1 . The access control subsystem 1 10 may be installed proximate the switchboard 10, even inside a housing of the switchboard 10. However, it is preferably installed at a location where an input arrangement of the access control subsystem 1 10 will be readily accessible by authorised personnel.

Each of the slave control subsystems 120 are interposed on one of the electricity lines 14 electrically downstream of the switchboard 10, between the switchboard 10 and a load/appliance 16. A portion of the electricity line after the slave control subsystems 120 is designated by reference numeral 14.1 . The slave control subsystems 120 may be arranged proximate the switchboard 10 (even in the switchboard housing), proximate the load/appliance 16, or somewhere in between. Preferably, the slave control subsystems 120 are arranged where their sensors would be useful, accessible, or exposed to the input which they are configured to sense.

FIGS 3-4 illustrate the subsystems 1 10, 120 in more detail. The access control subsystem 1 10 is so-called because it controls all access to electricity use by a building or installation in which the switchboard 10 is installed. The access control system 1 10 comprises a master switch 1 12, a user input in the form of a keypad 1 14, and a master controller 1 16. The master switch 1 12 is configured to connect or disconnect the master electricity input 12 from the switchboard 10. The keypad 1 14 is operable to receive a coded input, in the form of a PIN, from a user. The master controller 1 16 is configured to compare the received coded input against at least one correct code and, in response to the coded user input matching a correct code, to open or close the master switch 1 12.

The master controller 1 16 may store plural correct access codes. For example, a first code may be operable only to turn the master switch 1 12 on, a second code may be operable only to turn the master switch 1 12 off, and a third code may be operable either to turn the master switch 1 12 on or off. A building supervisor or forearm may be supplied with a correct access code, so that the access control subsystem 1 10 may be actuated only by authorised personnel and not by general employees.

The slave control subsystem 120 comprises a slave switch 122, a sensor 124, and a slave controller 126. The slave switch 122 is configured to connect or disconnect the split electricity line 14.1 from the switchboard 10. The sensor 124 is configured to receive an external signal, usually a signal generated by a user. The slave controller 126 is operable to open or close the slave switch 122 in response to receipt of the sensed signal, or in response to determining that the sensed signal complies with predefined switching criteria.

By way of technical trials, the Applicant has implemented the subsystems 1 10, 120 in hardware modules. FIGS 5 onwards illustrate these example hardware implementations and also describe in more detail the functionality of the subsystems 1 10, 120.

FIGS 5-7 illustrate schematic circuit diagrams of the access control subsystem 1 10. The access control subsystem 1 10 has a power supply unit 1 18 comprising a transformer, a rectifier, and a voltage regulator. The keypad 1 14 is approximated by 1 0 switches (S1 -S1 0) representing 1 0 digits (0-9). The master controller 1 1 6 comprises two 4044 latches, a comparator, and a D flip-flop. The switch 1 1 2 comprises a transistor and a relay.

The access control subsystem 1 1 0 uses eight (8) combinations of codes, at least one of which must be keyed in in the right order, to toggle the switch 1 1 2. The access control subsystem 1 10 uses a CD4044 (quad NAND R/S Latch) which is cross-coupled to a 3-state R/S latch with a common output enable. Each of the latches has a separate 'Q' output and individual SET (S) and RESET (R) inputs.

The "Q" outputs are controlled by a common enable input. A logic "1 " or high on the enable input connects the latch states to the "Q" outputs. In other words, a low on the enable input disconnects the latch states from the Q-outputs, resulting in an open circuit feature. The pin description of the 4044 is shown in Table 1 , and the basic operation is shown in a truth table in Table 2.

Table 1 : Pin description of CD4044 Inputs

Output Qn

Enable Sn Rn

L X X Z

H L H H

H X L L

H H H Latched

Table 2: Truth Table of CD4044 (where X = Don't care; Z = High impedance; Latched = No change)

The second sub-stage is the voltage comparator which uses LM393 to compare the final output of the second CD4044 latch with a fixed voltage at the Pin 2 of the LM393. If the output of the Pin 1 of 4044 IC is high, which serves as the input to the Pin 3 of the LM393, the output of the comparator (LM393) is set high, hence, clocking the third sub-stage that utilises 7474 (dual positive edge-triggered D flip-flop). Once clocked, the output of the flip-flop remains in that state until it sees another signal. The output of the flip-flop (Pin 5, 1 Q) helps in setting VBE of the switching transistor (BC1 07BP) high (approx. 0.67 V); forcing the voltage at the collector low, which in turn allows the coil of the relay to magnetized and switching from normally open to close. With this action, the circuit is complete and the electricity is switched on or off depending on the state it was before the correct combinations of codes. A truth table describing the operation of 7474 (D flip-flop) IC is shown in Table 3.

Table 3: Positive-edge triggered flip-flop

In FIG. 5, a button S1 -S1 0 on the keypad 1 14 has not yet been pressed. The 4044 IC is an active low device; this means that both the set and reset latch are only activated when they receive little or no input voltage. By taking advantage of this property, both the set and reset latches are set to receive high input voltages to keep them inactive. Since the set latch SO is not active, the output "00" becomes 0 V. Output "00" activates reset latch R1 and this sets output 01 to 0 V too. This pattern continues on until the last reset latch and ensures that there is no output voltage when the correct switches have not been pressed.

In FIG. 6, a correct key (switch S5) is pressed. As S5 is activated, the whole 12 V from supply is dropped across R5 and this causes a low input signal at the set latch "SO". Since the device is active low, "SO" is activated and an output of 5 V is released from output "OO". The output from Ό0" then goes to reset latch "R1 " and then deactivates it. This ensures that when the next correct switch "S6" is pressed the set latch "S1 " is ready to receive the signal and give out a 5 V output. As long as the correct switches are activated in the right order, the pattern will go on until the last output is 5 V.

If, however, as wrong key is pressed, the reset latch "RO" is activated and this resets output "OO" to 0 V. This then leads to the reset of latch "R1 " which resets output "01 " to 0 V. This pattern goes on until all of the reset latches have been activated and all of the outputs are set to 0 V. This ensures that only the correct sequence of keys can turn on the device and also ensures that the wrong switches reset any wrong attempts.

FIG. 7 illustrates a correct complete code received. Once all the correct switches have been pressed, the last output of the second 4044 IC is set to 5 V. The output then activates the comparator which then sends a clock signal to the D flip-flop. Having being activated, the D flip-flop will give out a continuous 5 V until it is clocked again. The output of the flip-flop biases the NPN transistor which then allows current to flow and switching the relay on. The line 12.1 is effectively connected to the master electricity input 12.

FIGS 8-10 illustrate schematic circuit diagrams of the slave control subsystem 120. FIGS 8-9 illustrate an infra-red embodiment of the slave control subsystem 120, which also includes a power supply unit 128. The slave switch 122 has a transistor and a relay. The sensor 124 includes a photosensitive diode. The slave controller 126 comprises a comparator, a 555 timer, and a D flip-flop. A remote control 130 is also provided, which includes an infra-red transmitter which is configured to generate a signal frequency of about 38 KHz.

In FIG. 8, the switch S1 of the remote control 1 30 is not pressed. T4 is open circuit, and all the supply voltage is dropped across it (approx. 1 2 V). In such case, a voltage seen at the non-inverting pin of the comparator (pin 3) is higher than the voltage at the inverting input, which then drives the comparator output high using a pull-up resistor R3 (approx. 12V). Since the voltage seen at the trigger pin (pin 2) of the timer is high (more than one-third of the Vcc), the output of the timer (pin 3) is low, as such, the clocking pin of the D flip-flop receive no signal so that the VBE of the switching transistor (2N3904) will not be enough to drive the transistor on, leading the slave switch 1 22 to remain in the open state.

In FIG. 9, the switch S1 of the remote control 1 30 is pressed, and the voltage seen at the pin 3 of the comparator is low due to the fact that enough voltage is seen at the base of the transistor, as such, the collector goes low (approx. 1 7.9 mV), and almost all the voltage is dropped across R7. In such case, voltage seen at the trigger pin (pin 2) of the 555 timer is low (approx. 1 7.6 mV), which is less than one-third of the supply voltage (1 2V), which allows the 555 timer to operate in the monostable stage, during which the time required to go low depends on the timing circuit of R26 and C2. During the process, the output of the 555 timer is high, leading to a signal to clock the 7474 flip-flop, which then biases the base of the transistor and forces the collector of the transistor to go to a low state, causing a coil of the relay to be magnetised and forcing the normally open contact to close, and drive the circuit attached to the unit on or off, depending on the state it was before receiving the present signal.

FIG. 1 0 illustrates a different embodiment of the slave control subsystem 1 20, in which the sensor 124 is an acoustic sensor. The sensor 1 24 may comprise a microphone (which has been approximated by a switch S1 in the illustration) to pick up a sound and convert it to an electrical signal (voltage). The voltage seen at the non-inverting terminal of the operational amplifier (LM324 op-amp) is about 20 mV, which is then amplified using the op-amp. When amplified, the base of the transistor Q1 (BC1 07BP) is biased and triggers the 555 timer, which in turn clocks the D flip-flop, allowing it to change state from either low to high, depending on the state it was before receiving the present signal.

FIG. 1 1 shows a circuit diagram of the whole system 100, including the access control subsystem 1 10 and two types of slave control subsystem 120.

FIG. 12 illustrates a schematic view of a PCB of the access control subsystem 1 10 and FIG. 13 shows a schematic view of a corresponding layout of the PCB of the access control subsystem 1 10.

FIG. 14 illustrates a schematic view of a PCB of the infra-red embodiment of the slave control subsystem 120 and FIG. 15 shows a schematic view of a corresponding layout of the PCB of the slave control subsystem 120.

FIG. 16 illustrates a schematic view of a PCB of the acoustic embodiment of the slave control subsystem 120 and FIG. 17 shows a schematic view of a corresponding layout of the PCB of the slave control subsystem 120.

The Applicant believes that the invention as exemplified is advantageous in that it permits both course control of electricity supply to a building, dwelling, installation, factory, or the like, as well as fine control of electricity supply to each of the loads/appliances therein, based on predefined sensor configurations, without requiring modifications of the distribution unit or of the loads/appliances themselves. In other words, greater control of global electricity supply is permitted, as well as rendering existing appliances "smarter" and more controllable in the electricity use.