IES930437A2 - Improvements in and relating to electrical units - Google Patents

Abstract

An electrical unit such as an immersion heater controller (30) has a support bracket (34) which has an opening (37) 5 to allow installation by connection to an in situ unit such as an immersion heater switch without disconnection of wires. The wires "pass" through the opening (37) for connection to the in situ unit so that electrical connections may be made simply. The circuits operate 10 independently of the mains supply and long battery life is ensured by use of a high current gain circuit between logic and switching circuits.

Description

ABSTRACT Improvement in and a relating to electrical units An electrical unit such as an immersion heater controller (30) has a support bracket (34) which has an opening (37) to allow installation by connection to an in situ unit such as an immersion heater switch without disconnection of wires. The wires pass through the opening (37) for connection to the in situ unit so that electrical connections may be made simply. The circuits operate independently of the mains supply and long battery life is ensured by use of a high current gain circuit between logic and switching circuits.

EH\SPEC1\30085(2).MAY IE 930437 ι I A I 4P«UCa' $93 ίίάΖ in and Relating to Electrical Units The invention YStcrtes to electrical units such as switches, timers, controllers or any other type of electrical unit. The invention is particularly, but not exclusively, applicable to wall-mounted electrical units such as immersion heater switches, immersion heater controllers, light switches or any other wall-mounted electrical unit. However, the invention applies to other types of electrical units also.

One object of the invention is to provide for the connection or installation of an auxiliary electrical unit to an in situ electrical unit in a simple manner with the minimum requirement for electrical expertise. In this specification, the term in situ means a unit which is already installed such as mounted on a wall, which is pre15 connected to wires and ready for installation, or which will be installed. An example is the connection of an additional light switch to an existing light switch, of a timer to an immersion heater switch, of a metering device to an electrical system for transmission of data to a remote location, or of a remotely commanded switch to an air conditioning unit. As will be appreciated from this list of examples, an in situ unit may be in two parts having a base which is either stand-alone or for connection to a wall or other object, and a cover which is connected both electrically and mechanically to the base.

In another example, the in situ unit may take the form of a combined base and cover which is directly connected to another object such as a wall. An example of the latter type is a light switch which is secured directly to a wall.

OPEN TO PUBLIC iNPPBQTIQN UNDER SECTION 23 AND RULE 23 JNL. No.../##........OF T/ IE 930437 - 2 Another object of the invention is to provide for reliability in an electrical unit such as a timer or controller.

A still further object of the invention is to provide a 5 simple and inexpensive construction of electrical unit such as a timer or controller.

According to the invention, there is provided a support bracket for connection of an auxiliary unit to an in situ unit, the support bracket comprising:10 means for supporting the auxiliary unit; means for connection to the in situ unit, said means having an opening so that the bracket may surround an electrical wire of the in situ unit without disconnection of the wire; and a passageway in the support bracket to allow an electrical wire be fed from the in situ unit to the auxiliary unit.

In one embodiment, the bracket has a closure for the opening.

Preferably, the closure is constructed so that when it is inserted over the opening, it presents a flush outer surface for continuity of the bracket.

The closure may be connectable to the bracket. The closure may be connectable in any suitable manner such as by use of male/female engagement members, by a hinge, or by force-fitting.

IE 930437 - 3 The passageway in the support bracket may be an opening between that portion of the bracket which connects to the in situ unit and that portion which supports the auxiliary unit. The opening may be formed, for example, by a recessed cross-bar across the support bracket.

According to another aspect, the invention provides an electrical unit housing comprising a unit body supported in a support bracket as described above.

In one embodiment, the unit body is releasably connected to the support bracket.

In this latter embodiment, the bracket and the unit body are preferably constructed for connection of the unit body within the support bracket at different orientations around the bracket for versatility of installation of the electrical unit.

In a still further embodiment, the unit body and the support bracket may be constructed so that the unit body may be connected to the support bracket in one of two directions to face in either one of two opposed directions.

Thus, either front or rear surfaces of the support bracket may face outwardly, in use. This allows, for example, the unit body supported by the support bracket to protrude outwardly from a wall where the in situ unit comprises a cover directly connected to a wall. Alternatively, where the in situ unit comprises a base secured to the wall and a cover, the front face of the unit body may be flush with the front cover of the in situ unit because the unit body extends over the base of the in situ unit.

IE 930437 - 4 In another embodiment, an operator interface of the unit body is rotatable within the unit body for versatility of installation of the electrical unit.

In one embodiment, the support bracket includes a 5 removable cover for the passageway for shielding of electrical wires, in use. The cover may be hinged.

In a still further embodiment, the unit body may comprise a back-panel spaced-apart from the casing of the unit body to cover over wires leading from the unit body to the portion of the support bracket connectable with the in situ unit.

According to another aspect, the invention provides a control circuit for an electrical controller, the control circuit having an independent power supply for operation independently of an electrical system to which it may be connected .

According to another aspect, the invention includes an electrical unit having an electrical unit housing as described above and unit circuits.

In one embodiment the electrical unit has terminals for connection with an electrical system, and the circuits include a control circuit having an independent power supply for operation independently of the electrical system.

Preferably, the control circuit is battery-powered.

In one embodiment, the control circuit comprises a means for providing a high current gain between a logic circuit and a switching circuit connected to the terminals.

IE 930437 In this latter embodiment, the current gain means preferably comprises means for providing low saturation switching characteristics to ensure that the switching circuit is operated, reliably with a deteriorating battery.

The switching circuit is preferably a low-voltage relay. The relay may be a low-voltage bi-stable relay.

Preferably, the duration of a high current gain pulse is controlled by an RC circuit.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which :Figs. la is a diagrammatic sketch showing a simple support bracket of the invention, and Figs, lb to Id are diagrammatic sketches showing the broad principle of one aspect of the invention.

Fig. 2 is a diagrammatic perspective view showing an alternative construction of support bracket of the invention; Figs. 3a and 3b are perspective views showing an electrical unit, in this case an immersion heater controller of the invention; Fig. 4a to 4c are perspective views showing the immersion heater controller of Fig. 3b being installed in an electrical system; Figs . 5 and 6 are perspective views showing alternative constructions of electrical units, also immersion heater controllers of the invention; SE Γ'·' Fig. 7 is a diagrammatic front view showing versatility of installation of the electrical unit of Fig. 6; Fig. 8 is a perspective view from above showing a still further construction of support bracket and unit body for an immersion heater controller; Fig. 9 is a diagrammatic view from behind showing a unit body forming part of the electrical unit of Fig. 8; Fig. 10 is a diagrammatic cross-sectional side view 10 showing the support bracket of the electrical unit of Fig. 8 in more detail; Fig. 11 is a front view of an alternative construction of support bracket of the invention; Figs. 12a and 12b are front and diagrammatic cross15 sectional views respectively showing an electrical unit incorporating the support bracket of Fig. 11; Figs. 13a to 13f are various views showing the unit body of the electrical unit of Fig. 12 in more detail; Fig. 14 is a circuit diagram of part of the circuit of 20 an electrical unit of the invention; and Figs. 15 and 16 are graphs showing operation of the electrical unit.

Before referring directly to the drawings, the invention provides a support bracket which has the following principal features:1. It can support an auxiliary electrical until such as a timer to be connected to the switch for an immersion heater system, 2. it can be connected to an in situ electrical unit such as, in this example, a wall mounted switch for the immersion system, and 3. it incorporates a passageway to allow an electrical wire lead from the in situ unit to the auxiliary unit, in this example, from the wall mounted switch to the timer.

Figs. 1 and 2 illustrate these broad, principal features in a simple manner. Fig. la shows an extremely simple construction of support bracket 1 which has a rectangular frame 2 having an opening 3 at one end. The frame 2 has a pair of screw-holes 4.

The manner in which the support bracket 1 may be used for connection of an auxiliary electrical unit to an in situ electrical unit will now be described with reference to the diagrammatic sketches of Figs, lb to Id inclusive.

Fig. lb shows an in situ electrical unit, namely an electrical switch 10 having a unit body, namely, a switch body 11 and housing terminals 12 which are connected to electrical wires 13 which run in ducting in a wall 14. This is a completely conventional switch unit.

Referring now to Fig. lc, the support bracket 2 is shown supporting an auxiliary switch unit 6. The auxiliary switch unit 6 has switch terminals 7 connected to free electrical wires 8. For connection of the auxiliary switch unit 6 to the in situ switch unit 10, the latter is simply unscrewed from the wall and is pulled away from the wall a short distance. The bracket 10 is then pushed - 8 IE laterally with the leads 7 (still connected) passing through the opening 3 in the bracket 2. The electrical leads 8 are then connected to the terminals 12 of the in situ electrical switch 10. Subsequently, the switch unit is pushed against the bracket 2 and screws are used for securing the switch unit 10 in position against the wall 14, clamping the bracket 2 against the wall.

It will be appreciated that the invention provides for connection of the auxiliary switch 6 in an extremely simple manner to the in situ switch 10 because there is no need to disconnect the leads 13 and the mechanical fasteners for the in situ unit 10 may be used for physical support of the auxiliary switch 6. It will thus be appreciated that very little skill is required for installation of the auxiliary switch 6.

To keep the above description simple, the example of a light switch is used. However, the invention applies to numerous types of electrical units, as described below.

Referring now to Fig. 2, there is shown another construction of support bracket, indicated by the numeral 20. The support bracket 20 comprises a rectangular frame 21 having a compartment 22 for supporting an auxiliary electrical unit and a compartment 23 for connection to an in situ electrical unit. The two portions of the support bracket 20 are connected by a passageway, namely, an opening 24 to allow electrical leads pass from one to the other. The support bracket 20 includes an opening 25 having a closure, in this embodiment, a hinged closure 26. It will be appreciated that when the support bracket 20 is used it forms a flush outer surface after the closure 26 has been put into position.

Having now described the invention in very simple terms, various embodiments of the invention will now be described in detail.

In Figs. 3a and 3b, an electrical unit of the invention, 5 namely, an immersion heater timer or controller is shown and indicated generally by the reference numeral 30. In this embodiment, the support bracket is incorporated in the unit body. The controller 30 comprises a unit body 31 which houses various control circuits and has user interface keys 32 and a display unit 33. The unit body 31 is integral with a support bracket 34. The support bracket 34 has a rectangular frame 35 having various screw-holes 36 for connection with an in situ unit. In addition, the support bracket 34 has an opening 37 with a hinged closure 38. Electrical leads 39a and 39b are fed from circuits within the unit body 31 and through a pair of holes in the support bracket 34 into the rectangular frame 35. This pair of holes forms a passageway between the two parts of the support bracket 34.

Referring now to Figs. 4a to 4c, the manner in which the controller 30 is connected to an in situ immersion heater switch 40 is shown. The in situ switch 40 comprises a wall-mounted casing 41 and a front panel 42 having screwholes 43 for securing in place against the casing 41 and the wall. Electrical leads 44 run between ducting in the wall and the front panel 43. Again, this is a conventional immersion heater switch.

To connect the controller 30, the front panel 42 is simply removed from the casing 41 by unscrewing it. The support bracket 34 is then pushed in position in front of the casing 41 surrounding the electrical leads 44 which pass through the opening 37. The closure 38 is then closed in position across the opening 37. Subsequently, various electrical connections are made between the leads 39a and 39b and the in situ leads 44 and terminals, not shown, in the front panel 43. Then, the front panel 43 is screwed back into position, the screws passing through the screw5 holes 36 in the support bracket 34 to secure it in position .

As explained in more detail below, because the control circuits within the controller 30 have an independent power supply, a neutral power connection is not required, thus simplifying the installation procedure. The only electrical requirement is to break the live connection, preferably at the switch. The live lead is removed from the switch 40 and the wire 39b is placed in the terminal from which the live lead was removed. The live lead from the power source is now connected to the terminal at the end of the lead 39a. The electrical wiring is now complete, a neutral connection not being required. Of course, the controller 30 could be connected to any other suitable in situ unit such as a socket or an interface.

Referring now to Fig. 5, an electrical unit, namely, an immersion heater controller 50 is disclosed. Parts similar to those described with reference to Figs. 3 and 4 are identified by the same reference numerals. The controller 50 has a unit body 51 which is telescopically slidable within a support bracket 52 to adjust the spacing between the rear of the unit 51 and the front of the bracket 52.

Referring now to Fig. 6, there is shown an electrical unit, namely, an immersion heater controller 60 having a unit body 61 with a rotatable interface 62. The advantage of this arrangement is shown in Fig. 7 where it is shown that the controller 60 may be installed at any of four different positions, at each of which position the user IE 930437 interface is easily readable because it is at the correct orientation .

Referring now to Fig. 8, a still further construction of an electrical unit also an immersion heater controller is now shown. The unit 70 comprises a support bracket 71 which may releasably support a unit body 72 by resilient engagement between indentations 7 3 in the unit body 7 2 and formations 74 on the interior surface of the support bracket 71. A passageway between the portion of the bracket 71 supporting the unit body 7 2 and that portion which connects with an auxiliary unit is formed by a recessed cross-member 75. This passageway may be covered over in use by a hinged cover 76. In this embodiment, there is a closure 77 across an opening of the support bracket 71. The closure member 77 is connected to the support bracket 71 by tongue and groove fittings. The unit body 72 includes a spaced-apart back panel 78 which defines a space in which an electrical lead 79 runs from a terminal and through the passageway. As shown in fig. 9, the electrical lead 79 may be pulled in any desired direction, depending on the orientation at which the unit 7 2 is inserted into the support bracket 71. This is facilitated because the portion of the bracket 71 supporting the unit 7 2 and the unit 7 2 itself are of square shape in front view. The manner in which the electrical lead 79 passes through the passageway so that it may be connected to the in situ unit is shown clearly in Fig. 10.

The support bracket 71 is shown in more detail in Fig. 11 in front view and in Figs 12a and 12b, the manner in which the unit body 72 is connected in position is shown. The unit body 72 has a display unit 85, control buttons 86 and a battery compartment 87.

IE 930437 - 12 The unit body 72 is shown in particularly good detail in Figs. 13a to 13f. The battery compartment 87 has a hinged door for insertion of batteries.

It will be appreciated that the mechanical construction of 5 the electrical unit of the invention provides for extremely simple installation. Indeed it allows, for example, an unskilled person to connect a timer to an immersion heater electrical system. Versatility is achieved by the fact that the controller may be connected at any one of at least four orientations because the controller body may be re-inserted in the support bracket so that the interfaces may be viewed easily by the user. Because the controller body may be inserted in either of the opposed directions into the support bracket, the support bracket and the rear of the controller body may be flush with the wall, or alternatively the support bracket may be spaced-apart between a front cover and a casing for an existing unit, with the back of the controller body extending rearwardly over the casing of the existing unit.

The invention may be applied to connection of additional light switches, for example where the new casing is supported between an existing switch casing and the wall. Disconnection of wires is kept to a minimum because the support bracket has an opening which surrounds the existing wires.

Another important aspect of the invention is the fact that the circuit of the controller operates independently of the mains supply. This is very important to protect it from power cuts and lightning strikes or any other situation where the mains supply is irregular. Thus, the control circuit is battery-powered by a single 1.5V alkaline penlight cell which has a life of five to seven years. This has many advantages including:13 it reduces the number of electrical connections which are required on installation; there is high noise immunity from mains-borne interference; there is a very low power dissipation in the order of micro Watts in the controller and therefore no heat is generated and stress on components is greatly decreased and safety is enhanced; fewer components are required; and 10 the controller may be programmed before installation.

Referring now to Figs. 14 and 15, a current gain and switching circuit 90 forming part of the controller 1 is shown. The purpose of the circuit 90 is to use the 50 μΑ output from logic circuits, namely, a microcontroller (not shown) which is the input A to provide a very high current for switching of the order of 20 A via the relay contacts. The circuit 90 comprises a bistable relay circuit comprising coils RL1A and RL1B, across which are connected back EMF suppressing diodes and transistors Qi and Q4. One coil is for switching on, the other for switching off.

The relay RL1A is also connected to a transistor Q3 and the relay RL1B is connected to a transistor Q2. The circuits associated with each relay may be regarded as the A and B circuits, respectively. For control of the A circuit there is a pair of inverters U1A and U1B and a timing circuit made up of a capacitor Ci and a resistor Rj. For the B circuit there is an inverter U1C which is connected to the input via an RC circuit C2/R2· The circuit 90 operates on the principle that the configuration Qu Q2 and Q3, Q4 provide high current gain IE 930437 and low saturation switching characteristics. The output of inverters U1B and Ulc are normally high. When a change of state occurs at input A, either inverter output will go low for a duration determined by the RC time constant, thus turning on either Qj or Q4 and its associated saturating switch Q3 or Q2. The overall current gain is the product of the combined gains of the individual transistors .

Alternatively, when the microcontroller provides a 10 negative-going pulse at the input A, this turns Q4 on and Qx is turned off.

The circuit operates as follows. Fig. 14 shows a series of inverters and time constants acting as a pulse steering mechanism. The output from the microcontroller is sent to input A. A positive going signal at A drives output B to ground. This does not effect input E as it is already at ground through Rl. However, input F is at ground through R2 and is driven high by input A. This output D goes low switching on the on coil of RL1 for a period determined by R2, C2 (normally 10-15 mSec depending on relay characteristics). When a negative going signal appears at A, output B goes high and input E thus drives output C low switching on the off coil of RL1 for a period determined by Cl Rl. However, input F is already at ground and ignores the negative going signal.

The entire circuit 40 can of course be inverted such that Qi and Q2 are NPN and Q3 and Q2 are PNP. A positive going pulse is then required from the inverters U1B and U1C.

Referring now to Fig. 16 there is shown a typical immersion heater requirement of 10 x 10 millisecond pulses. The total on time in a 24 hour period is 10 x 10 milliseconds or 0.1 second.

IE 930437 - 15 Total number of seconds in 24 hours = 85400.

Duty cycle = 1:864000 Average current consumption for switching circuit only is 0.85 amp divided by duty cycle or 0.85 = 0.983 x IO'6 or 0.98Microamp 864000 Therefore, the average switching current is only 0.98 Microamps.

Add this average of 0.98 to the average for the microcontroller of 5Microamps as follows: Total average = 5 + 0.98 = 5.98 or 6 microamps rounded.

The capacity of an alkaline AA cell is 2.2 ampere hours or greater. If we divide 2.2 by the total average current, the total working hours available is:15 2.2 divided by 6 x 10’6 = 2.2 x 106 divided by 6 = 366666 hours or 366666 hours divided by 8760 = 41.85 years.

But of course in reality this is impossible because the battery has an intrinsic leakage current and will deteriorate without load.

However, the quality of modern alkaline cells has improved considerably and a shelf life of 4 years is common. Shelf life is defined as when the cells capacity is reduced to 85% of nominal. Therefore an AA cell with a capacity of 2.2. ampere hours will have a working capacity of 1.87 ampere hours. After 4 years the cell can still deliver far in excess of the current requirements of controller 1 (peak 850mA).

Another interesting phenomenon occurs in relation to the invention, namely a cell's ability to recover chemically after a short burst of power, keeping in mind that the circuit consumes real power for only 10 milliseconds. The inventor has tested very discharged cells which recovered in 4 to 5 minutes after delivering an 850 mA pulse for 10 milliseconds. This is an added bonus enhancing longevity.

The invention is not limited to the embodiments hereinbefore described. For example, the invention may be applied to timers, indicating lights, switches, controllers or interrogative, interactive or remote control sensing devices of any type. The support bracket of the invention may be used particularly advantageously for interconnection of units where one of the units is wall-mounted, however, it is envisaged that it may alternatively be used for hand-held instruments or other situations where two units are interconnected. Such situations include units mounted in a panel, control box, rack, or on machines or pumps. Applications of the invention include random light switching for security purposes, light dimmers, laboratory timers, residual current devices, high quality mains filters for sensitive instruments and computer applications, mains-borne remote control units, mains-borne security applications, and mains-borne computer applications such as networks and metering and telemetry applications.

It will be appreciated that the invention enables intervention in a simple manner, in an existing installed electrical circuit which may have appliances, equipment or other devices connected to it by placing at any convenient and appropriate location in the circuit, including at a IE 93043? switch, fused link, socket, outlet, isolator, circuit breaker, residual current device, interface unit, junction box, ceiling rose, ceiling switch, or other such electrical unit, a desired electrical or electronic unit to command, control, measure, protect, switch, interrogate, interact with or exchange information with, said circuit or the equipment and appliances it supplies. The invention is not limited to a single-gang application but may be employed with two or multi-gang connections where convenient.

The subsequent functioning of the electrical or electronic units so installed may be effected manually, mechanically or automatically, for instance, in response to a pre-set value of, or effect in the electric circuit, or in response to a predetermined externally sensed event such as sound level or the intensity of light. Groups of them may receive commands from, interact with, or report to remotely located equipment and devices enabling companies to control a multitude of circuits for instance, or utilities to switch a multitude of appliances or remotely read a multitude of meters.

In fact, the invention enables the placing and connection of almost any type of device which is electrically or electronically powered, or the outputs of which can be converted to electrical signals in a particularly quick, safe and simple manner from both electrical connection and mechanical mounting points of view to an electrical circuit or circuits so giving control over, or interaction with it, or them. Further, a high degree of immunity from electrical and electromagnetic noise, spurious signals and from mechanical stress due to overheating or continuous exposure to heat arising internally in the device so fitted, is provided.

The independent power source is not confined to an alkaline battery - any other suitable type of battery may be used including a lithium battery. Electromagnetic or solar radiation could provide the power, pressure of sound or other pressure, or any other available or incident power source could be used. The power for the device could of course be obtained from the circuit to which the device is fitted but thereby losing the advantages of the independent power source.

The following comments may also be made. The invention may embrace or encompass technology for information interchange e.g. security sensors, detectors for monitoring any radiant energy, sounders, annunciators, intercoms or modems for information interchange. The communication modes may be ultra sound or audible sound, light energy, any electromagnetic radiation, solar or any other incident energies, by means of or employing all forms of modulation and encoding, including spread spectrum, mains-borne carrier and encoding systems, radio paging, microwave, optic or laser transmission and encoding, and any electrical magnetic or radio carrier or modulation techniques. A factory could readily retrofit a variety of devices so that certain process heaters would come on automatically before the first shift, lights could be switched off automatically when ambient lighting reached a certain intensity, security devices would automatically come into operation at nightfall, machines and devices could be controlled by intelligent systems over e.g. radio carriers, without need to install control wiring (particularly useful for continuous processes or in hazardous or hostile conditions). Residual current devices could be retro fitted throughout.

It is envisaged that a water temperature sensor in the form of a metal clip onto a water pipe may be connected to 930437 the controller and used to indicate temperature or to switch on or off the immersion heater and, by sliding it into different positions on the pipe, to give an added degree of control, reliability or economic operation to the functioning of the immersion heater.

CLAIMS;

Claims (5)

1. A support bracket for connection of an auxiliary unit to an in situ unit, the support bracket comprising: means for supporting the auxiliary unit; 5 means for connection to the in situ unit, said means having an opening so that the bracket may surround an electrical wire of the in situ unit without disconnection of the wire; and a passageway in the support bracket to allow an 10 electrical wire be fed from the in situ unit to the auxiliary unit.

2. A support bracket as claimed in Claim 1, further comprising a closure for the opening; any one or more of the following:15 a closure constructed so that when it is inserted over the opening it presents a flush outer surface for continuity of the bracket; a closure connectable to the bracket; a closure connectable to the bracket in any 20 suitable manner such as by use of male and female engagement members, or a hinge, or by forcefitting .

3. An electrical unit housing comprising a unit body supported on a support bracket as claimed in any preceding claim, in which the unit body may be integral with the support bracket, or alternatively may be reieasabiy connected to the support bracket, in which IE 930437 - 21 case the bracket and unit body may be constructed for connection of the unit body at different orientations around the support bracket, and in which the unit body and the support bracket may be constructed so that the

4. 5 unit body may be connected in one of two directions to the support bracket to face in either one of two opposed directions . An electrical unit comprising an electrical unit housing as claimed in Claim 3 and unit circuits, in which the electrical unit may further comprise terminals for connection with an electrical system, in which case the circuits may include a control circuit having an independent power supply for operation independently of an electrical system, in which the control circuits may be battery-powered and may comprise a means for providing a high current gain between a logic circuit and a switching circuit connected to the terminals, in which the current gain means may comprise means for providing low saturation switching characteristics to ensure that the switching circuit is operated reliably with a deteriorating battery, and the switching circuit may be a low-voltage relay and may be a low-voltage bi-stable relay.

5. A support bracket in all its novel features as 25 described in the specification and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.