WO2011092475A1

WO2011092475A1 - Voltage control apparatus

Info

Publication number: WO2011092475A1
Application number: PCT/GB2011/000113
Authority: WO
Inventors: Paul John Carter
Original assignee: C & C Marshall Limited
Priority date: 2010-01-29
Filing date: 2011-01-28
Publication date: 2011-08-04
Also published as: GB2477327A; GB201215133D0; GB2494961B; GB2494961A; GB201001532D0

Abstract

The present invention relates to an apparatus, system and method for controlling voltage. The voltage control apparatus, which is for controlling the voltage of a domestic power supply, comprises an electrical input (108, 109, 208, 209, 308, 309, 408, 409) for receiving an electrical supply having an associated input voltage, a voltage control means (101, 102, 103, 104, 201, 202, 203, 204, 30, 302, 303, 304, 40, 402, 403, 404) arranged to receive the electrical supply from the electrical input (108, 109, 208, 209, 308, 309, 408, 409) and to selectively reduce the input voltage, and an electrical output (110, 111, 210, 211, 310, 311, 410, 411) arranged to provide an output supply to a consumer unit 10, the output supply having a voltage in accordance with the selectively reduced input voltage.

Description

Voltage Control Apparatus

The present invention relates to an apparatus, system and method for controlling voltage. More specifically, the apparatus of the present invention is arranged to control the voltage of an electrical supply before the electrical supply enters a consumer unit. In particular, the present invention aims to reduce the input voltage supplied to a consumer unit to thereby reduce resultant energy wastage.

Electricity suppliers provide electrical power via electricity supplies to homes, businesses and industries across a wide geographical area. In Europe, electricity supplies vary in respect of their operating voltage. It has been known for such operating voltages to be from about 210V up to 265V. However, the European Union Voltage Harmonisation directive has defined that all electricity supplies must be provided at 230V +6% -10%, which equates to anything from 207.0V to 243.8V. Given the variations allowable under the European Union Voltage Harmonisation directive there have in fact been few changes in the voltage levels supplied across Europe because most European countries operate off either a 220V or 240V supply, thereby falling within this range.

In order to increase the profitability of mass produced consumer electronic and electrical products many companies manufacture a single product suitable for re-sale across the whole of the European market. As a consequence most electrical items are designed to work at the lower-end of the above-mentioned voltage range, for example 210V to 220V. Operating at the lower end of the allowable voltage range ensures that the product is provided with sufficient operating voltage across the whole of the European market

For those countries such as the UK which provide a 240V electricity supply, use of electrical products which have been designed to operate at 220V, as mentioned above, results in any excess voltage which is delivered to the product being dissipated as heat. Hence, in countries such as the UK it is common for 20V of electricity to be constantly wasted by electrical products.

This is a known problem and in order to attempt to tackle the problem various ways forward have been proposed. One popular solution to the problem has been to utilise a step-down transformer in order to step the 240V supply down to 220V. However, utilising such a transformer can cause problems, for example, if a load of more than 220V is required by a device the device may not be able to function properly.

In order to overcome this problem, systems have been proposed that utilise bypass functionality. Such bypass functionality allows for a transformer that is converting a 240V supply into a 220V supply to be bypassed in favour of the 240V supply when a 240V supply is required.

However, these systems are known to require unduly large transformer components. Consequently, such systems can be unduly large as well as impractically expensive to produce. Furthermore, the switching of these transformers can cause unwanted spikes in the electrical characteristics of the supply. Hence, partly due to the size and expense of such systems it has generally only been practical to provide such voltage control apparatus in an industrial setting.

Applying these systems in an industrial setting involves installing the devices to operate along side industrial distribution boards. Industrial distribution boards draw large levels of current and therefore the electrical requirements of such voltage control systems have to be designed accordingly. Furthermore, due to the differing power requirements of industrial buildings, such systems require an individual set-up and calibration such that they can operate efficiently in the specific industrial setting. In addition, the current drawn in an industrial setting can vary substantially on an hour-by-hour basis, consequently, known systems usually require large amounts of load or transformer switching in order to compensate for such current variations. The present inventor has therefore realised that it is therefore impractical to utilise similar systems in a domestic setting because the requirements of an industrial setting differ so substantially.

Known voltage control apparatuses are therefore too large, expensive and impractical for use in a domestic setting.

The present invention aims to at least partly mitigate the aforementioned problems of the prior art. An embodiment of the present invention also aims to provide a voltage control apparatus, which may reduce power wastage as much as possible.

An embodiment of the present invention aims to provide a voltage control apparatus, which is cheap to manufacture.

An embodiment of the present invention also aims to provide a voltage control apparatus, which is suitable for use in a domestic setting.

An embodiment of the present invention aims to provide a voltage control apparatus, which is capable of operating with large current drawing loads connected.

According to a first aspect of the present invention there is provided a voltage control apparatus for controlling the voltage of a domestic power supply, comprising: an electrical input for receiving an electrical supply having an associated input voltage; a voltage control means arranged to receive the electrical supply from the electrical input and to selectively reduce the input voltage; and an electrical output arranged to provide an output supply to a consumer unit, the output supply having a voltage in accordance I with the selectively reduced input voltage.

In an embodiment of the invention, the voltage control means further comprises: a voltage reduction device arranged to reduce the input voltage by subtracting a reduced voltage, derived from the received electrical supply, from the input voltage of the i received electrical supply.

In a further embodiment of the invention, the voltage reduction device is a transformer circuit and comprises: a primary winding connected across the electrical input; and a secondary winding having a first terminal connected to a terminal of the electrical input ) and a second terminal connected to a terminal of the electrical output, the secondary winding arranged such that a negative voltage is induced therein from the electromotive force caused by electric current flowing through the primary winding and the voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage. In an additional embodiment of the invention, the reduced voltage, which is subtracted from the input voltage of the received electrical supply, is variable.

In an embodiment of the invention, the voltage reduction device comprises a plurality of interconnected secondary windings arranged to selectively be connected or bypassed to provide a variable reduced voltage.

In a further embodiment of the invention, each secondary winding has an associated switch arranged to connect or bypass the respective secondary winding.

In another embodiment of the invention the secondary winding has a plurality of tappings arranged to selectively be connected to provide a variable reduced voltage.

In a further embodiment of the invention the secondary winding includes a variable actuator arranged to slide along the winding of the secondary winding to provide a variable reduced voltage.

In an additional embodiment of the invention, the voltage control means further comprises a switching assembly arranged to switch such that the electrical output is connected to either the received electrical supply or the reduced voltage output supply.

In an embodiment of the invention, the switching assembly is arranged to connect the electrical output to the received electrical supply by providing a short circuit across the voltage reduction device.

In a further embodiment of the invention, the switching assembly is arranged to connect the electrical output to the electrical supply received at the electrical input, and thereby bypass the voltage reduction device, when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

In an additional embodiment of the invention, the switching assembly comprises: a first switch operable to connect the electrical output to the received electrical supply when a current being drawn by the voltage control apparatus is above a threshold; and a second switch, arranged in parallel with the first switch, operable to connect the 2011/000113

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electrical output to the received electrical supply when the voltage reduction device changes the connection state of a secondary winding of the plurality of interconnected secondary windings.

In an embodiment of the invention, the first switch is a relay and the second switch is a semiconductor-type switch. in a further embodiment of the invention, the voltage control apparatus further comprises a current monitor arranged to monitor a current being drawn into the voltage control apparatus for determining whether the electrical output should be connected to the received electrical supply or the output supply having a reduced voltage in accordance with the reduced input voltage of the voltage control means.

In an additional embodiment of the invention, the voltage control apparatus further comprises a controller for controlling the operation of the voltage control apparatus.

In an embodiment of the invention, the voltage control apparatus is provided with a consumer unit in a common housing such that electrical output of the voltage control apparatus can provide an input to the remainder of the consumer unit.

In a further embodiment of the invention, the voltage control apparatus further comprises a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

According a further aspect of the present invention there is provided a voltage control apparatus, comprising: an electrical input for receiving an electrical supply having an associated input voltage; a voltage control means arranged to receive the electrical supply from the electrical input, the voltage control means comprising: a voltage reduction device arranged to selectively reduce the input voltage by subtracting a reduced voltage, derived from the received electrical supply, from the input voltage of the received electrical supply; and an electrical output arranged to provide an output supply, the output supply having a voltage in accordance with the selectively reduced input voltage. In an embodiment of the invention, the voltage reduction device is a transformer circuit and comprises: a primary winding connected across the electrical input; and a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of the electrical output, the secondary winding arranged such that a negative voltage is induced therein from the electromotive force caused by electric current flowing through the primary winding and the voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

In a further embodiment of the invention, the reduced voltage, which is subtracted from the input voltage of the received electrical supply, is variable.

In an additional embodiment of the invention, the voltage reduction device comprises a plurality of interconnected secondary windings arranged to selectively be connected or bypassed to provide a variable reduced voltage.

In an embodiment of the invention, each secondary winding has an associated switch arranged to connect or bypass the respective secondary winding.

In a further embodiment of the invention, the voltage control means further comprises: a switching assembly arranged to switch such that the electrical output is connected to either the received electrical supply or the reduced voltage output supply.

In an additional embodiment of the invention, the switching assembly is arranged to connect the electrical output to the received electrical supply by providing a short circuit across the voltage reduction device.

In an embodiment of the invention, the switching assembly is arranged to connect the electrical output to the electrical supply received at the electrical input, and thereby bypass the voltage reduction device, when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

In a further embodiment of the invention, the switching assembly comprises: a first switch operable to connect the electrical output to the received electrical supply when a current being drawn by the voltage control apparatus is above a threshold; and a second switch, arranged in parallel with the first switch, operable to connect the electrical output to the received electrical supply when the voltage reduction device changes the connection state of a secondary winding of the plurality of interconnected secondary windings.

In an additional embodiment of the invention, the first switch is a relay and the second switch is a semiconductor-type switch.

In an embodiment of the invention, the voltage control apparatus further comprises a current monitor arranged to monitor a current being drawn into the voltage control apparatus for determining whether the electrical output should be connected to the received electrical supply or the output supply having a reduced voltage in accordance with the reduced input voltage of the voltage control means.

In a further embodiment of the invention, the voltage control apparatus further comprises a controller for controlling the operation of the voltage control apparatus.

According to a further aspect of the present invention there is provided a voltage control system, comprising: a voltage control apparatus according to any of the aforementioned embodiments of the invention; and a consumer unit arranged to receive the output supply of the electrical output of the voltage control apparatus and provide a plurality of output supplies derived from the electrical output of the voltage control apparatus.

According to another aspect of the present invention there is provided a method for controlling the voltage of a domestic power supply, comprising: receiving an electrical supply having an associated input voltage; selectively reducing the input voltage; and providing an output supply to a consumer unit, the output supply having a voltage in accordance with the selectively reduced input voltage. In an embodiment of the invention, the step of selectively reducing the input voltage comprises subtracting a reduced voltage, derived from the electrical supply, from the input voltage.

In a further embodiment of the invention, the reduced voltage is produced by: providing a primary winding connected across an electrical input such that when current flows through the primary winding an electromotive force is produced; and providing a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of an electrical output; wherein the electromotive force produced by the primary winding induces a negative voltage in the secondary winding such that a voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

In an additional embodiment of the invention, the step of selectively reducing the input voltage further comprises varying the reduction of the input voltage.

In an embodiment of the invention, the method further comprises determining whether to connect or bypass each of a plurality of interconnected secondary windings to provide a variable reduced voltage.

In a further embodiment of the invention, the method further comprises providing a short circuit across a voltage reduction device, which selectively reduces the input voltage, such that the electrical output is connected to the received electrical supply.

In an additional embodiment of the invention, the method further comprises connecting the electrical output to the electrical supply received at the electrical input when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

In an embodiment of the invention, the method further comprises monitoring a current being drawn; and selectively reducing the input voltage according to the current being drawn.

According to yet another embodiment of the present invention there is provided a method for controlling voltage, comprising: receiving an electrical supply having an associated input voltage; selectively reducing the input voltage by subtracting a reduced voltage, derived from the electrical supply, from the input voltage; and providing an output supply, the output supply having a voltage in accordance with the selectively reduced input voltage.

In an embodiment of the invention, the step of selectively reducing the input voltage comprises.

In an embodiment of the invention the method further comprises determining whether to connect or bypass each of a plurality of interconnected secondary windings to provide a variable reduced voltage.

In a further embodiment of the invention the method further comprises providing a short circuit across a voltage reduction device, which selectively reduces the input voltage, such that the electrical output is connected to the received electrical supply.

In an additional embodiment of the invention the method further comprises connecting the electrical output to the electrical supply received at the electrical input when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings. In an embodiment of the invention the method further comprises monitoring a current being drawn; and selectively reducing the input voltage according to the current being drawn.

In yet another embodiment of the present invention the voltage control means provides a fixed reduction in the voltage. In particular, a predetermined voltage reduction is provided by a transformer which is either placed in an ON or OFF state in order to output a reduced or full voltage respectively.

In a further embodiment of the invention, the method further comprises providing a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

Embodiments of the present invention provide a voltage control apparatus that reduces power wastage. Such power reduction is possible because the voltage control apparatus feeds a reduced voltage electricity supply to a consumer unit, the consumer unit then uses this reduced supply for all loads. Power is also saved by the simplicity of the circuit used to provide the voltage reduction because power wastage due to heat dissipation is minimised.

Embodiments of the present invention also provide a voltage control apparatus which is cheap to manufacture. In particular, the transformer arrangement used to provide the step down voltage does not require expensive transformer components and can therefore make significant savings over known step-down transformer systems. Furthermore, semiconductor switches can be used in the place of power transformers as has been known to be required in the prior art.

Embodiments of the present invention provide a voltage control apparatus, which is suitable for use in a domestic setting. It is possible to utilise the present invention in a domestic setting because the transformer has been optimised for the lower power requirements of the domestic setting. Furthermore, the design of the voltage control apparatus of the present invention allows for the apparatus to be small, and inexpensive to produce, thus being suitable for the domestic setting. In addition, the specific transformer arrangement, and in particular the way in which it reduces the voltage is more suited to the domestic setting. As mentioned above, the present invention is suitable for use in a domestic environment, for example in a private house or apartment, and it is also suitable for use in other environments with similar power requirements, such as light industrial or retail environments.

The unit of the present invention is suitably configured so that power dissipated in the unit is a small proportion of the maximum power capacity of the consumer unit, being preferably less than 10% of the power capacity.

Embodiments of the present invention will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a standard consumer unit;

Figure 2 shows a consumer unit and voltage control apparatus according to an embodiment of the present invention;

Figure 3 shows a detailed view of a voltage control apparatus provided in accordance with an embodiment of the present invention;

Figure 4 shows an alternative embodiment of the invention, in which a voltage reduction device 201 having a plurality of tappings is provided;

Figure 5 shows yet another alternative embodiment of the invention, in which a variable transformer control circuit 312 is provided;

Figure 6 illustrates a further alternative embodiment of the invention incorporating an improved switching means; and

Figure 7 provides a flow chart illustrating the monitoring and processes carried out by the controller.

Throughout the description and drawings like reference numerals shall refer to like parts.

Figure 1 shows a standard consumer unit 10 provided and connected as is known in the art. A consumer unit is a device which is installed within all homes, offices and light industrial or retail buildings at the point of entry of the electricity supply. A consumer unit is a device that distributes an electricity supply throughout a building, taking a single input power supply and splitting the supply into a plurality of supplies which can be separately distributed to different circuits or devices within the building. The consumer unit preferably not only splits the electricity supply into a plurality of circuits or channels, but also provides individual circuit breakers and fuses for each of these portions.

In the UK, such consumer units must comply with the requirements of the 7^th Wiring Regulations BS7671. As a consequence, such units also include a Residual Current Device (RCD), which detects problems such as current leakage within the load being supplied. Furthermore, such consumer units are generally arranged to provide a current of up to about 50A.

As shown in Figure 1 the consumer unit 10 is provided with a main switch 12. The supply lines 11, which carry the incoming electricity supply, connect directly to the main switch 12. The main switch 12 therefore provides a single switching point which can stop all electricity from entering the consumer unit, and therefore the building or area that the consumer unit supplies. The main switch is arranged to trip, that is automatically switch off, if, for example, an excess current is drawn.

The consumer unit 10 splits the electricity supply, after it has passed through the main switch 12 into a plurality of different portions. As mentioned above these portions may correspond to particular devices to be powered, or to a particular group or area of devices. Each portion is provided with an output port 14a-d, which allows for an electrician to connect a device or further network of devices to that portion of the consumer unit 10. Between the main switch 12 and each output port 14a-d a miniature circuit breaker (MCB) 13a-d or DIN-rail mounted circuit breaker is provided. These circuit breakers 13a-d are arranged to provide a means for automatically preventing electricity to flow to that portion in the event that an excess current is drawn, possibly due to a short circuit or the like. Hence, the circuit breakers 13a-d act as a safety device.

In a standard consumer unit, as depicted in Figure 1 and described above, the voltage received at the input of the consumer unit is transferred to each output provided by the consumer unit. Consequently, when such a consumer unit 101 is used in the UK it outputs 240V to each portion. Devices connected to the consumer unit, or a portion thereof, requiring only 220V to operate will, therefore, waste power. Figure 2 shows how a voltage control apparatus 100 of an embodiment of the present invention can be connected between the supply lines 11 , which carry the incoming electricity supply, and the consumer unit 10. Providing the voltage control apparatus in this location means that 220V can be provided to the whole consumer unit and all devices connected thereto. Consequently, energy wastage can be minimised.

It will be appreciated that the voltage control apparatus need not be totally separate from the consumer unit and could instead be housed with the consumer unit within a common enclosure. In such a case the voltage control apparatus would effectively form the first stage of the new improved consumer unit, with the voltage control apparatus placed before or upstream of the electrical distribution features of a standard consumer unit. In different embodiments of the invention it would be possible to place the voltage control apparatus before or after a main switch of the consumer unit. It is envisaged that there would be various ways of integrating the voltage control apparatus with the consumer unit such that the functionality of the voltage control apparatus is provided upstream of the distribution functionality of the consumer unit.

Figure 3 provides a more detailed illustration of a voltage control apparatus in accordance with an embodiment of the present invention.

The voltage control apparatus of Figure 3 is arranged suitable for use in a domestic setting. For example, the voltage control apparatus is for use in a domestic environment such as a house, or apartment, and also in any environment having similar power requirements such as a light industrial building, or retail outlet.

The voltage control apparatus 100 of Figure 3 includes a voltage control means including a voltage reduction device 101 , a switching assembly 102, a controller 103, and a current monitoring transformer 104. The voltage control apparatus 100 also comprises a plurality of miniature circuit breakers (MCBs) 105, 106 and a thermal switch 107.

The voltage control means is arranged for reducing the input voltage, for example from 240V to 220V. The switching assembly is provided to bypass the functionality of the voltage reduction device, which carries out the voltage reduction from 240V to 220V, when a controller determines, by a measurement obtained from the current monitoring transformer, that more power is being drawn by the load. A voltage control apparatus is therefore provided, which is suitable for feeding a consumer unit.

The voltage control apparatus of Figure 3 and each of its elements shall now be described in detail.

An electrical input is provided by a live electrical input supply line 108 and a neutral electrical input supply line 109. The electrical input is arranged to receive the electrical supply prior to the electrical supply entering the consumer unit or any other device. When utilised in a domestic setting the electrical input is arranged to receive the electrical supply entering the house or apartment such that the voltage control apparatus feeds the consumer unit for the house or apartment.

The live electrical input supply line 108 and the neutral electrical input supply line 109 will generally be wires/cables, preferably of a thickness matching the wires/cables that carry the electrical supply to the house or apartment. In some embodiments of the present invention special connectors are provided in order to connect the live electrical input supply line 108 and the neutral electrical input supply line 109 to the supply entering the house or apartment.

An electrical output comprising a live output terminal 110 and a neutral output terminal 111 is provided. The voltage control apparatus 100 is arranged to control the voltage received at the electrical input and then provide a voltage at the electrical output derived from the electrical input. Any device that connects to the live output terminal 110 and neutral output terminal 1 11 should effectively receive the electrical supply which passes through the voltage control apparatus as it would if the voltage control apparatus were not there, except that the voltage of the electrical supply may have been controlled by, for example, reducing the voltage.

The live output terminal 110 and the neutral output terminal 111 are arranged to connect to the input of a consumer unit. Hence, it may be necessary to provide the live output terminal 110 and the neutral output terminal 111 with connectors such it is quick and simple to connect the voltage control apparatus 100 to the consumer unit. The current monitoring transformer 104 is connected to the live electrical input supply line. In particular, one terminal of a first coil of the transformer is directly connected to the live electrical input supply line 108, while the other end of the first coil of the transformer is both connected to a portion of the switching assembly 102 and a portion of the voltage control means 101. The terminals of the second coil of the transformer are connected to the controller 103.

In operation, when a load (not shown) draws current through the voltage control apparatus 100, the current firstly passes through the current monitor 104. The current monitor works as follows.

As current is drawn by a load (not shown) connected to the output of the voltage control apparatus 100 current will flow through the first coil of current monitor 104 and induce a current in the windings of the second coil of current monitor 104. The induced current is indicative of the load and therefore current being drawn by the voltage control apparatus. The controller 103 can then monitor the current flowing through the second coil to determine the current being drawn by the voltage control apparatus 100. As discussed in more detail later, the controller 103 can then determine whether to switch the switching assembly 102 in accordance with whether or not it is determined that an excessive current is being drawn.

The voltage reduction device 101 provides the means for reducing the voltage and therefore saving energy. In this embodiment of the present invention the voltage reduction device is a transformer apparatus, and is arranged to step-down the input voltage such that energy is not dissipated as heat. Furthermore, a laminated transformer is used as the basis of the transformer apparatus. A laminated transformer is cheaper and smaller than many other types of transformer. However, alternative types of transformer could be used. The characteristics of the transformer utilised in this embodiment of the present invention are advantageous in an industrial setting.

In this embodiment of the present invention the transformer apparatus is arranged to have a voltage of 240V applied across its input, and provide a voltage of approximately 220V across its output. It will be appreciated that the present invention could be utilised with different input and output voltage as well as different step-down ratios. The reduction from 240V to 220V is therefore provided as an example of this particular embodiment of the present invention.

The voltage reduction device 101 comprises a primary winding 101a, which is connected between the live electrical input supply line 108 and the neutral electrical input supply line 109. The input voltage is therefore applied across the primary winding 101a. A transformer core 101b is then provided adjacent to the primary winding 101a. The voltage reduction device 101 also includes a plurality of secondary windings 101c- f.

In this embodiment of the invention four secondary windings 101c-f are utilised, however, it will be appreciated that any number of secondary windings could be used. Furthermore, it may be desired to only provide a single secondary winding. If a single secondary winding were used this could be accompanied by an arrangement that allowed the single winding to provide a variable voltage, or could form part of a simpler fixed, non-variable voltage reduction device providing a fixed voltage drop. Alternative embodiments incorporating some of these concepts are discussed in more detail below.

The four secondary windings 101c-f are each connected to an individual switching arrangement. The switching arrangement of the first secondary winding 101c has a switching member connected at one end to both the current monitoring transformer 104 and the switching arrangement 102. The switching arrangement of each winding is preferably in the form of a single pole triple throw relay. Since the current monitoring transformer 104 passes the current drawn by the load, the switching member of the first secondary winding 101c is effectively connected directly to the live electrical input supply line 108. This switching member is then arranged to connect the live electrical input supply line either to the first or second terminal of the first secondary winding 101c. The second terminal of the first secondary winding 101c is then connected to the switching member of the second secondary winding 101d. Consequently, if the switching member of the first secondary winding 101c is connected to the first terminal of the first secondary winding 101c, electric current is arranged to flow through the first secondary winding. Alternatively, if the switching member of the first secondary winding 101c is connected to the second terminal of the first secondary winding 101c then the first secondary winding is bypassed. Each of the secondary windings 101 c-f is connected in exactly the same way such that a cascade of windings is provided. The second terminal of the fourth secondary winding 101f then provides the live output terminal.

In operation, when each of the four secondary windings 101 c-f are connected the voltage provided between the live output terminal 110 and the neutral output terminal 111 , which is directly connected to the neutral electrical input supply line, is equal to the sum of the input voltage minus the negative voltage produced in each of the secondary windings 101 c-f by the electromotive force (emf) induced in those windings by the electromotive force produced by the primary winding 101a. Hence, the output voltage is the result of the input voltage with the sum of the negative voltages produced by each of the secondary windings subtracted therefrom.

The negative voltage produced by each of the secondary windings 101 c-f can be set by the ratio of turns of each secondary winding when compared to the number of turns of the primary winding. Such concepts of winding ratios are commonly known in the art.

By switching some of the switching arrangements of the secondary windings 101c-f ON and others OFF, different voltage drops can be achieved, thereby providing a variable voltage reduction device. Clearly, there is a balance to be struck with respect to the number of secondary windings provided. The more windings that are provided will allow for smaller steps in voltage, which may be advantageous. However, as the number of windings increase so does the complexity and efficiency of the apparatus.^'

In addition, it is preferable that the number of windings provided by each of the secondary windings 101c-f is equal such that switching of the secondary windings 101 c-f provides a controlled and measured change in the voltage reduction. However, in alternative embodiments of the invention it may be preferable for each secondary winding to have a different number of windings.

While in the present embodiment a variable voltage reduction switching arrangement is provided that utilises a series connection of individual cascaded secondary windings, in alternative embodiments of the present invention other means for providing a variable voltage could be provided. For example, a single secondary coil could be provided with a sliding variable adjustment mechanism. Alternative known means for varying the voltage in a transformer could be utilised. However, the above-described embodiment of the present invention is a preferred arrangement because it allows for simple control of the variation of the voltage provided by the voltage reduction device.

Each of the switching members of the secondary windings 101c-f is controlled by controller 103. In particular, the controller determines the input voltage in accordance with the current monitored by the current monitoring transformer 104. From the input voltage, which may in itself be variable, the controller is arranged to determine the voltage reduction that is required to provide an output voltage of approximately 220V. The controller then switches each of the switching members of the secondary windings 101 c-f to control the flow of current through the windings, and as a consequence the voltage drop provided is controlled. In the embodiment illustrated by Figure 3 each of the switching members is connected to each respective first terminal of each secondary winding 101 c-f and therefore the maximum voltage reduction is provided.

Hence, the voltage reduction device 101 of this embodiment of the present invention allows for a variable reduction in the voltage by use of a transformer based circuit. In particular, a transformer based circuit which subtracts a voltage, derived from the input voltage, from the input voltage to produce a reduced voltage. This system allows for a smaller more efficient voltage reduction, which is consequently much more suitable for use in a domestic environment.

We shall now consider the switching assembly 102 in more detail. The switching assembly 102 is arranged to provide a bypass functionality with respect to the voltage reduction device 101 in the event that a voltage greater than 220V needs to be supplied. In particular, the switching assembly 102 bypasses the voltage reduction device 101 and outputs the input voltage of 240V.

As shown in Figure 3, switching assembly 102 is connected at a first terminal to the current monitor 104 and switching member of the first secondary winding 101c of the voltage reduction device 101 and at a second side to the live output terminal 110. Hence, a voltage equivalent to the voltage drop provided by the voltage reduction device 01 is provided across switching assembly 102 when the switching assembly 102 is in an open state. The switching assembly 102 is provided such that, for example, if the input voltage is found to get too low for the voltage reduction to be advantageous, or the power being drawn by the load requires a higher output voltage, then the switching assembly 102 can be switched ON. By switching the switching assembly 102 to the ON state the live electrical input supply line 108 can be directly connected to the output terminal 110 such that the output voltage is the same as the input voltage. Hence, when the switching assembly 102 is switched to the ON state it provides a short circuit across the secondary windings 101c-f of the voltage reduction device 101 such that the voltage reduction device 101 is effectively deactivated.

In this embodiment of the present invention the switching assembly 102 comprises a relay (not illustrated), which when activated connects the live electrical input supply line 108 to the output terminal 110. The relay is operated by the controller 103, which can determine the input voltage and current being drawn by the current monitoring transformer 104. If the input voltage gets too low or the current being drawn by the load is too high, the controller 04 sends a switching signal to the switching assembly 102 such that the relay 102 is activated and therefore allows for the input voltage to be provided at the output.

In addition to acting as a means for outputting the input voltage, the switching assembly 102 is also switched to the ON state during regulation changes. That is the switching assembly 102 is switched to the ON state whenever the controller 103 switches one of the switching arrangements of the secondary windings 101c-f of the voltage reduction device 101. The bypass functionality of the switching assembly 102 is then used in order to avoid any interruptions to the supply output by the voltage control apparatus 100. Overall this functionality ensures that the regulation switching is both smooth and also overcomes the problems of "switching transients", which can otherwise occur.

In order to provide for improved switching during regulation changes it is preferable to provide a semiconductor switch in parallel with the relay. The semiconductor switch is therefore used for switching during regulation changes and the relay is used in the circumstances discussed in detail above. Using a semiconductor switch allows for improved prevention of switching transients, particularly as the regulation changes could be frequent. Furthermore, a semiconductor switch is cheap, fast acting, and long lasting.

In the embodiment of the present invention as shown in Figure 3 a plurality of miniature circuit breakers (MCBs) 105,106 are provided. The MCBs are provided in order to attempt to protect the circuit from overload or short circuit. A first MCB 105 is provided between the live electrical input supply line 108 and a first terminal of the primary winding 101a of the voltage reduction device 101. A second MCB is provided between a second terminal of the fourth secondary winding 101f and the output terminal 110.

The embodiment of the present invention shown in Figure 3 also includes a thermal switching device 107. The thermal switching device 107 is arranged between the second MCB 106 and the output terminal 110. This switching device is provided to be placed in an ON position in the normal state and if it is sensed that the voltage reduction device 101 is overheating then it switches to the OFF position.

The thermal switching device 107 may have the functionality to sense the temperature of the voltage reduction device completely integrated with the switching functionality. However, in the preferred embodiment of the present invention the sensing is carried out by the controller, or a sensing apparatus connected to the controller, and the controller then provides a switching signal to the thermal switching device 107 when necessary.

The controller can then also be attached to a cooling device, such as a fan, which Can help to cool the system. Hence, when the controller senses that the system is starting to overheat, for example by sensing that the temperature is higher than a predetermined threshold temperature, the controller can control a fan. As such, the fan can blow air over the particularly hot parts of the system, such as the transformer, in order to move hot air out of the system, and thereby cool the system. The casing of the system may be provided with venting in order to improve circulation of air to further aid cooling.

The cooling system may be arranged to vary a level of cooling responsive to a monitored temperature. It may be that the cooling system merely switches on at a predetermined temperature. The predetermined temperature defined in accordance with a temperature at which damage to device may occur. Alternatively, the cooling system may increase its level of cooling as a measured temperature increases. Hence, the level of cooling may be proportional to the temperature in order to attempt to maintain the temperature of the device at a level that allows for the device to operate without fault.

While the cooling system of this embodiment of the invention is described as a fan it will be appreciated that various other types of cooling system could be utilised.

The controller 103, which has so far been described with reference to each of the other components of the voltage control apparatus 100 is a microcontroller. It can take the form of a programmable logic device such as an FPGA, or be a specifically designed microprocessing device combined with specific memory functionality. In addition, the controller must be provided with the functionality to drive the relay of the switching assembly 102, particularly if a common 12V relay is used.

The controller 03 is arranged for monitoring the current passing through the current monitoring transformer. Once a current is determined the controller 103 is able to determine the current input voltage and load being drawn. Consequently, the controller 103 is able to control the operation of the switching members of the secondary windings 101c-f of the voltage reduction device 101 in accordance with calculations as to the required output voltage, given the input voltage. Furthermore, the controller 103 is able to control the switching of switching assembly 102. In addition, the controller can control switching of the thermal switching device 107.

Figure 4 shows an alternative embodiment of the invention. In this embodiment of the invention an alternative voltage reduction device 201 is provided. It can be assumed that the other components of the system are the same as the previously described embodiment.

The voltage reduction device 201 includes a primary winding 201 a, similar to primary winding 101 a shown in respect of Figure 3. A single secondary winding 201c is then provided with a transformer core 201 b provided between the primary and secondary windings 201a, 201 c. A transformer control circuit 212 is provided within the voltage reduction device. The transformer control circuit is controlled by the controller 203. The transformer control circuit 212 has four 'tappings' connected to the secondary winding 201c. These tappings provide connections between the secondary coil and an output of the overall system. As such, the transformer control circuit 212 is arranged to select one of the tappings to connect the output of the system to the secondary winding 201c. The transformer control circuit 212 may consist of a relay, solid state logic, or any other suitable switching assembly. Each tapping is provided at a different point along the length of the secondary winding. As such, the voltage induced in the different lengths of the secondary winding, provided by the different tappings, thereby provides a different voltage reduction. Hence, the controller 203 can control the transformer control circuit to make different voltage reductions dependent upon the input current/voltage.

Figure 4 shows four tappings. These tappings may be provided in order to provide voltage reduction ratios of 0.96, 0.94, 0.92 and 0.9. It will be appreciated that different reduction ratios could also be utilised depending on the circuit requirements. In alternative embodiments, more or less tappings could be provided. The more tappings that are provided the more accurate the voltage adjustments can be because the incremental changes in voltage will be smaller.

Figure 5 shows yet another alternative embodiment of the invention. This embodiment is substantially the same as the embodiment described in respect of Figure 4, except that the transformer control circuit 212 is replaced by variable transformer control circuit 312. Rather than having a plurality of tappings like the control circuit 212, control circuit 312 has a variable actuator which is able to connect any point on the secondary winding to the output of the system. This may be achieved by providing an integrated secondary winding and variable actuator, wherein the actuator slides along a surface of the winding 301c (as shown by the arrows in Figure 6). The sliding actuator effectively shortens and lengthens the second winding 301c in order to vary the voltage. This embodiment of the invention effectively provides tappings at each winding of the secondary winding with the moveable actuator selecting one of the tappings.

This embodiment of the invention allows for very accurate adjustment of the output voltage. For example, the output voltage can be constantly adjusted by the variable transformer control circuit 312 based on measurements made by the controller 303. This allows for the voltage reduction to be varied in such a way that allows for the output voltage to remain constant irrespective of variations in the input voltage.

Figure 6 illustrates a further alternative embodiment of the invention incorporating an improved switching means. Those parts of the invention not described in detail with respect to Figure 6 are the same as the equivalent features described in the embodiments relating to Figures 3 to 5.

In this embodiment of the invention the switching between the voltage reduction mode and the bypass mode is carried out by the switching arrangement 413. This switching may be achieved by a relay, a solid-state switching topology or such like. The switching arrangement 413 is arranged so that the default position is bypass mode, in which the input voltage is passed directly onto the output. The arrangement in bypass mode shall now be described.

The switching arrangement 413 comprises a double pole double throw (DPDT) switch, or two single pole double throw (SPDT) switches. The input provided through electrical input supply line 109 is provided to point (a) of the first SPDT switch. In bypass mode the first SPDT connects point (a) to point (e), which is connected to the live output terminal 410.

In bypass mode the input of the second SPDT switch, point (b), is connected to point (g), which is an unconnected or 'dead' point, and therefore renders the switch inactive in bypass mode.

The switching arrangement 413 is arranged to receive control signals from controller 403. The controller 403 may supply control signals indicating that bypass mode is required. However, bypass mode may also be active in the absence of any control signal from the controller.

When the controller 403 determines that voltage reduction mode can be entered a control signal is sent from the controller to the switching arrangement 413. In response to receipt of the control signal the switching arrangement switches the first SPDT switch from point (e) to point (f) and the second SPDT switch from point (g) to point (h). In voltage reduction mode, the input supply line 408 is connected from point (a) of the first SPDT switch to point (f) of the first SPDT switch. As such the input supply is supplied to the transformer. The transformer 401 of Figure 6 is depicted as being the same as the transformer of Figure 3, however, it will be appreciated that any of the transformer arrangements discussed could be utilised. Point (b) of the first SPDT switch is connected to the output of the transformer 40 , and therefore supplies the reduced output voltage of the transformer 401. Point (b) of the first SPDT transformer is connected to point (h), which therefore connects the output of the transformer to the live output terminal 410.

The switching arrangement 413 will then remain in the voltage reduction mode until it receives a control signal specifying that it should switch to the bypass mode, or no control signal is detected, in which case the switch reverts to the default bypass mode.

The voltage control apparatus 400 of Figure 6 also includes a different thermal switching arrangement compared to that of previous embodiments. It will be appreciated that the different thermal switching mechanisms described could be applied to each of the described embodiments. Thermal switch or thermo-switch 414 is provided on the power supply line of the controller 403. The power supply line is provided from the input supply line 408 to the controller 403. The thermal switch 414 is operated by an activation part mounted on the transistor. The thermal switch 414 and activation part may be integrated components, in such a case the thermal switch 414 is mounted on the transistor 401. The activation part is arranged to operate a switching part so as to disconnect the power supplied to the controller 403 when the temperature of the transistor reaches a predetermined temperature deemed to be too high. This predetermined temperature may be a factory set temperature, or it may be user adjustable.

In the event that the power of the controller 404 is disconnected by the thermal switch the switching assembly 413 will no longer receive a control signal. Since no control signal is received by the switching assembly 413 the switching assembly 413 will revert to the default bypass mode. In this embodiment of the invention, while the first and second SPDT switches are described as separate switches they form part of a synchronously operable switch, for example, in the form of a DPDT switch discussed above. It is also noted that alternative switching arrangements could achieve the same functionality. For example, the second SPDT switch could be replaced by a single pole single throw (SPST) switch, wherein points (b) and (h) are connected when in voltage reduction mode, and disconnected when in bypass mode.

Figure 6 and other Figures do not detail all circuit components that may be required, but those important to understanding each of the embodiments of the invention. For example, it is preferable to place a miniature circuit breakers (MCB) before the transformer in order to provide circuit isolation.

Figure 7 provides a flow chart illustrating the processes carried out by the controller. The specific values, such as voltage and current values, provided in Figure 7 are preferred values, but the invention need not be limited to these values, and in alternative embodiments other values will be utilised. The steps involved in this process shall now be explained in detail.

At step S1 the controller determines if the supply voltage is above a threshold value of 234V. The threshold value may be set to any suitable voltage level. This step is carried out because if the voltage falls below this threshold value it is not appropriate to use the voltage reduction functionality. That is, the voltage reduction functionality would result in a voltage being output that is or could be too low for certain appliances to operate properly.

The measurement itself is carried out by the current monitoring transformer and the calculation by the controller. In particular, the controller compares the measured value with a threshold value stored in memory.

When controller determines that the voltage is above 234V the controller then determines if the current is greater than 1 amp, based on the measurements carried out by the current monitoring transformer. This is shown as step S2 on Figure 4. This step is carried out because if the current is less than 1 amp then there is insufficient current for the voltage reduction to take place and as such bypass takes place. If the current is greater than 1 amp, a further measurement is taken to see if the current is greater than 60 amps (see step S3). If the energy is greater than 60 amps it is determined that too much load will be being placed upon the system in energy saving mode, and as such bypass mode is selected (step S6). However, if the current is not greater than 60 amps then the relay is energised via the controller and the energy saving mode is entered (step S4).

Once the relay is de-energised, or if the supply voltage is not above 234V, then the controller continues to monitor the supply. This is shown by step S5.

At step S7 the temperature of the transformer is monitored. The controller, using an external or built-in temperature sensor as discussed above, is able to determine if the transformer is increasing in such a way that may lead to overheating. For example, a threshold temperature below the temperature at which problems due to overheating occur can be set. If the measured temperature increases beyond the threshold temperature then the controller determines that the transformer temperature is not ok. Otherwise the temperature is determined to be ok. This step helps to detect any problems with the transformer at an early stage, before the heat may start to affect other components within the enclosure of the device.

If the transformer temperature is deemed to be ok, then the controller determines if the enclosure temperature is too high (Step S8). A similar threshold temperature mechanism as described above can be utilised for this determination. This measurement is carried out to determine if the excess heat produced by the transformer and other components is affecting the performance of the system as a whole. Some components may have a lower operating temperature than others, and as such the threshold temperature should be set in order to prevent overheating of the component with the lowest operating temperature.

If the enclosure temperature is determined to be ok, at step S9 it is determined if the controller allows supply of the reduced voltage (Step S9). If the controller does allow supply, the controller returns from step S9 back step S1, keeping the system working in the voltage reduction mode. If at any of steps S7, S8 or S9 the controller is provided with a negative outcome, the controller will bypass the energy saving circuit (i.e. the transformer) in order to reduce the increasing temperature problems.

In alternative embodiments the controller may increase the productivity of one or more cooling devices, for example, the controller may increase the rotation rate of a fan. Steps S7, S8 and S9 can then be repeated at a predetermined later time in order to determine if the temperature has dropped sufficiently. If the temperature does not drop then the bypass mode may be entered.

Steps 1 to 9 will be periodically repeated in order to control switching of the relay while monitoring characteristics of the device.

The voltage control apparatus of any of the above embodiments may be provided with a user display and/or interface linked to the controller. The display can take the form of an LCD-type display or the like. The display can provide information such as the current voltage output, electrical current characteristics, KWH usage and the energy savings being made by the device. This information can be updated and presented in real-time. Furthermore, when taking the form of an interface, user controls can also be provided along with the user display in order to allow the user to manually operate the switching of both the switching members of the secondary windings 101c-f of the voltage reduction device 101 and the switching assembly 102.

The addition of automatic power-factor correction into the apparatus would be advantageous for various reasons, for example, the power consumption would be further reduced.

The above described embodiments of the present invention have only been provided as examples and it will be appreciated that various other embodiments of the invention are possible without departing from the scope of the appended claims.

Claims

CLAIMS:

1. A voltage control apparatus for controlling the voltage of a domestic power supply, comprising:

an electrical input for receiving an electrical supply having an associated input voltage;

a voltage control means arranged to receive the electrical supply from the electrical input and to selectively reduce the input voltage; and

an electrical output arranged to provide an output supply to a consumer unit, the output supply having a voltage in accordance with the selectively reduced input voltage.

2. The voltage control apparatus according to claim 1 , wherein the voltage control means further comprises:

a voltage reduction device arranged to reduce the input voltage by subtracting a reduced voltage, derived from the received electrical supply, from the input voltage of the received electrical supply.

3. The voltage control apparatus according to claim 2, wherein the voltage reduction device is a transformer circuit and comprises:

a primary winding connected across the electrical input; and

a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of the electrical outRut, the secondary winding arranged such that a negative voltage is induced therein from the electromotive force caused by electric current flowing through the primary winding and the voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

4. The voltage control apparatus according to claims 2 or 3, wherein the reduced voltage, which is subtracted from the input voltage of the received electrical supply, is variable.

5. The voltage control apparatus according to claim 4, wherein the voltage reduction device comprises a plurality of interconnected secondary windings arranged to selectively be connected or bypassed to provide a variable reduced voltage.

6. The voltage control apparatus according to claim 5, wherein each secondary winding has an associated switch arranged to connect or bypass the respective secondary winding.

7. The voltage control apparatus according to claim 4, wherein the secondary winding has a plurality of tappings arranged to selectively be connected to provide a variable reduced voltage.

8. The voltage control apparatus according to claim 4, wherein the secondary winding includes a variable actuator arranged to slide along the winding of the secondary winding to provide a variable reduced voltage.

9. The voltage control apparatus according to any preceding claim, wherein the voltage control means further comprises:

a switching assembly arranged to switch such that the electrical output is connected to either the received electrical supply or the reduced voltage output supply.

10. The voltage control apparatus according to claim 7 when dependent on any one of claims 2 to 8, wherein the switching assembly is arranged to connect the electrical output to the received electrical supply by providing a short circuit across the voltage reduction device.

11. The voltage control apparatus according to claim 7 when dependent on claim 5 or 6, wherein the switching assembly is arranged to connect the electrical output to the electrical supply received at the electrical input, and thereby bypass the voltage reduction device, when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

12. The voltage control apparatus according to claim 11, wherein the switching assembly comprises:

a first switch operable to connect the electrical output to the received electrical supply when a current being drawn by the voltage control apparatus is above a threshold; and a second switch, arranged in parallel with the first switch, operable to connect the electrical output to the received electrical supply when the voltage reduction device changes the connection state of a secondary winding of the plurality of interconnected secondary windings.

13. The voltage control apparatus according to claim 12, wherein the first switch is a relay and the second switch is a semiconductor-type switch.

14. The voltage control apparatus according any preceding claim, further comprising:

a current monitor arranged to monitor a current being drawn into the voltage control apparatus for determining whether the electrical output should be connected to the received electrical supply or the output supply having a reduced voltage in accordance with the reduced input voltage of the voltage control means.

15. The voltage control apparatus according to any preceding claim, further comprising a controller for controlling the operation of the voltage control apparatus.

16. The voltage control apparatus according to any preceding claim, wherein the voltage control apparatus is provided with a consumer unit in a common housing such that electrical output of the voltage control apparatus can provide an input to the remainder of the consumer unit.

17. The voltage control apparatus according to any preceding claim further comprising a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

18. A voltage control apparatus, comprising:

a voltage control means arranged to receive the electrical supply from the electrical input, the voltage control means comprising:

a voltage reduction device arranged to selectively reduce the input voltage by subtracting a reduced voltage, derived from the received electrical supply, from the input voltage of the received electrical supply; and an electrical output arranged to provide an output supply, the output supply having a voltage in accordance with the selectively reduced input voltage.

19. The voltage control apparatus according to claim 18, wherein the voltage reduction device is a transformer circuit and comprises:

a primary winding connected across the electrical input; and

a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of the electrical output, the secondary winding arranged such that a negative voltage is induced therein from the electromotive force caused by electric current flowing through the primary winding and the voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

20. The voltage control apparatus according to claims 18 or 19, wherein the reduced voltage, which is subtracted from the input voltage of the received electrical supply, is variable.

21. The voltage control apparatus according to claim 20, wherein the voltage reduction device comprises a plurality of interconnected secondary windings arranged to selectively be connected or bypassed to provide a variable reduced voltage.

22. The voltage control apparatus according to claim 21 , wherein each secondary winding has an associated switch arranged to connect or bypass the respective secondary winding.

23. The voltage control apparatus according to any one of claim 18 to 22, wherein the voltage control means further comprises:

24. The voltage control apparatus according to claim 20, wherein the secondary winding has a plurality of tappings arranged to selectively be connected to provide a variable reduced voltage.

25. The voltage control apparatus according to claim 20, wherein the secondary winding includes a variable actuator arranged to slide along the winding of the secondary winding to provide a variable reduced voltage.

26. The voltage control apparatus according to claim 23 when dependent on any one of claims 19 to 25, wherein the switching assembly is arranged to connect the electrical output to the received electrical supply by providing a short circuit across the voltage reduction device.

27. The voltage control apparatus according to claim 23 when dependent on claim 21 or 22, wherein the switching assembly is arranged to connect the electrical output to the electrical supply received at the electrical input, and thereby bypass the voltage reduction device, when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

28. The voltage control apparatus according to claim 27, wherein the switching assembly comprises:

a first switch operable to connect the electrical output to the received electrical supply when a current being drawn by the voltage control apparatus is above a threshold; and

a second switch, arranged in parallel with the first switch, operable to connect the electrical output to the received electrical supply when the voltage reduction device changes the connection state of a secondary winding of the plurality of interconnected secondary windings.

29. The voltage control apparatus according to claim 28, wherein the first switch is a relay and the second switch is a semiconductor-type switch.

30. The voltage control apparatus according to any one of claims 18 to 29, further comprising:

31. The voltage control apparatus according to any one of claims 18 to 30, further comprising a controller for controlling the operation of the voltage control apparatus.

32. The voltage control apparatus according to any one of claims 18 to 31 wherein the voltage control apparatus is provided with a consumer unit in a common housing such that electrical output of the voltage control apparatus can provide an input to the remainder of the consumer unit.

33. The voltage control apparatus according to any preceding claim further comprising a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

34. A voltage control system, comprising:

a voltage control apparatus according to any one of claim 1 to 33; and a consumer unit arranged to receive the output supply of the electrical output of the voltage control apparatus and provide a plurality of output supplies derived from the electrical output of the voltage control apparatus.

35. A method for controlling the voltage of a domestic power supply, comprising: receiving an electrical supply having an associated input voltage;

selectively reducing the input voltage; and

providing an output supply to a consumer unit, the output supply having a voltage in accordance with the selectively reduced input voltage.

36. The method according to claim 35, wherein the step of selectively reducing the input voltage comprises subtracting a reduced voltage, derived from the electrical supply, from the input voltage.

37. The method according to claim 36, wherein the reduced voltage is produced by: providing a primary winding connected across an electrical input such that when current flows through the primary winding an electromotive force is produced; and

providing a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of an electrical output; wherein the electromotive force produced by the primary winding induces a negative voltage in the secondary winding such that a voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

38. The method according to any one of claims 35 to 37, wherein the step of selectively reducing the input voltage further comprises varying the reduction of the input voltage.

39. The method according to claim 38, further comprising:

determining whether to connect or bypass each of a plurality of interconnected secondary windings to provide a variable reduced voltage.

40. The method according to any one of claims 35 to 39, further comprising:

providing a short circuit across a voltage reduction device, which selectively reduces the input voltage, such that the electrical output is connected to the received electrical supply.

41. The method according to claim 39, further comprising:

connecting the electrical output to the electrical supply received at the electrical input when the voltage reduction device changes a connection state of a secondary winding of the plurality of interconnected secondary windings.

42. The method according any one of claims 35 to 41 , further comprising:

monitoring a current being drawn; and

selectively reducing the input voltage according to the current being drawn.

43. The method according to any one of claims 35 to 42, wherein the method further comprises providing a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

44. A method for controlling voltage, comprising:

receiving an electrical supply having an associated input voltage;

selectively reducing the input voltage by subtracting a reduced voltage, derived from the electrical supply, from the input voltage; and providing an output supply, the output supply having a voltage in accordance with the selectively reduced input voltage.

45. The method according to claim 44, wherein the step of selectively reducing the input voltage comprises.

46. The method according to claim 45, wherein the reduced voltage is produced by: providing a primary winding connected across an electrical input such that when current flows through the primary winding an electromotive force is produced; and

providing a secondary winding having a first terminal connected to a terminal of the electrical input and a second terminal connected to a terminal of an electrical output; wherein

the electromotive force produced by the primary winding induces a negative voltage in the secondary winding such that a voltage provided at the electrical output is the summation of the input voltage and the negative induced voltage.

47. The method according to any one of claims 44 to 46, wherein the step of selectively reducing the input voltage further comprises varying the reduction of the input voltage.

48. The method according to claim 47, further comprising:

49. The method according to any one of claims 44 to 48, further comprising:

50. The method according to claim 48, further comprising:

51. The method according any one of claims 44 to 50, further comprising: monitoring a current being drawn; and

selectively reducing the input voltage according to the current being drawn.

52. The method according to any one of claims 44 to 51 , wherein the method further comprises providing a cooling system arranged to maintain the voltage control apparatus at an operable temperature.

53. Apparatus as hereinbefore described with reference to Figures 2 and/or 3.

54. A method as hereinbefore described with reference to Figures 2 and/or 3.