GB2554959A

GB2554959A - Sensor apparatus for sending overheating

Info

Publication number: GB2554959A
Application number: GB1700506.7A
Authority: GB
Inventors: John Fletcher Adam; Elaine Christine Heathcote
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-10-13
Filing date: 2017-01-11
Publication date: 2018-04-18
Also published as: GB201617411D0; GB201700506D0; GB2554913A; WO2018069720A1

Abstract

A sensor apparatus for sensing overheating comprises a heat sensing module 72 that is mountable to a heat transfer module 74 comprising an elongate heat conducting member 78. Heat sensing module 72 comprises a thermal switch which switches when the ambient temperature at the heat transfer module exceeds a threshold temperature. Thermal transfer module 74 can comprise a casing that partially encloses conducting member 78 and has apertures 81 to allow heated air to rise form components below it and heat transfer to the module 74; weak points 83 allowing it to be cut to length; and grooves 84 to engage heat sensing modules and brackets (fig 7C, 87) for mounting the sensing module. The area monitored by a heat sensing module is extended by using the heat transfer module which carries heat to it from electrical components such as a neutral bar, busbar, mains switch and line connections to a fuse, MCB, RCD or RCBO in a distributions board or consumer unit, which would otherwise be too far away to increase the temperature of the thermal switch to activate it. A resilient clip (fig 8B 90a) may allow a heat sensing module to engage a cable. .

Description

(71) Applicant(s):

Adam John Fletcher

Hague Avenue, WOODFIELD, Gloucestershire, GL11 6LX, United Kingdom

Heathcote Elaine Christine

Stroud Road, GLOUCESTER, Gloucestershire,

GL1 5AJ, United Kingdom (51) INT CL:

H01H 37/34 (2006.01) H01H 37/04 (2006.01)

H02B 13/025 (2006.01) H02H 5/04 (2006.01) (56) Documents Cited:

GB 1086445 A US 4956544 A

US 3827015 A JP S5637427 (58) Field of Search:

INT CL H01H, H02B, H02H Other: EPODOC, WPI (72) Inventor(s):

Adam John Fletcher Heathcote Elaine Christine (74) Agent and/or Address for Service:

Spinnaker IP Limited

Cams Hall, Cams Hill, Fareham, Hampshire, PO16 8AB, United Kingdom (54) Title of the Invention: Sensor apparatus for sending overheating

Abstract Title: Overheating sensor for electrical connections and components (57) A sensor apparatus for sensing overheating comprises a heat sensing module 72 that is mountable to a heat transfer module 74 comprising an elongate heat conducting member 78. Heat sensing module 72 comprises a thermal switch which switches when the ambient temperature at the heat transfer module exceeds a threshold temperature. Thermal transfer module 74 can comprise a casing that partially encloses conducting member 78 and has apertures 81 to allow heated air to rise form components below it and heat transfer to the module 74; weak points 83 allowing it to be cut to length; and grooves 84 to engage heat sensing modules and brackets (fig 7C, 87) for mounting the sensing module. The area monitored by a heat sensing module is extended by using the heat transfer module which carries heat to it from electrical components such as a neutral bar, busbar, mains switch and line connections to a fuse, MCB, RCD or RCBO in a distributions board or consumer unit, which would otherwise be too far away to increase the temperature of the thermal switch to activate it. A resilient clip (fig 8B 90a) may allow a heat sensing module to engage a cable.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

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Sensor Apparatus for Sensing Overheating

Technical Field

The present invention relates to a sensor apparatus for sensing overheating, for example overheating of electrical circuits, connectors (for example connections and terminals) and components.

Background

Overheating of electrical components may arise due to various problems leading to poor electrical connectivity. Such problems may arise due to incorrectly tightened screws, loose wires, corrosion, mechanical fatigue and the like. These problems may cause overheating and consequently electrical fires. In WO266/125996, it was proposed to use a thermal switch to detect such occurrences of overheating. In WO2014/006356, an implementation of such a sensing apparatus was proposed in which an array of thermal switches in a carriage was provided, making installation of the sensor apparatus more straightforward than installation of multiple discrete sensors. However, this solution resulted in installation difficulties if the components to be monitored were not arranged perfectly linearly, and a lack of flexibility of installation. It will be appreciated that overheating can also be experienced in other contexts, such as in the case of a fire.

The present invention is intended to address certain of these limitations.

Summary of the Invention

According to the present invention, there is provided a sensor apparatus for sensing overheating, the apparatus comprising a heat sensing module and a heat transfer module, the heat transfer module comprising an elongate heat conducting member, and the heat sensing module being mountable to the heat transfer module and comprising a thermal switch which switches when the ambient temperature at the heat transfer module exceeds a threshold temperature. In this way, a single heat sensing module can be used to monitor for overheating over a larger area or at a plurality of electrical components (or other potential heat sources). Put another way, the area monitored by a heat sensing module is extended by using the heat transfer module, which carries heat to the heat sensing module from electrical components (or other heat sources) which would otherwise be too far away to increase the temperature of the thermal switch sufficiently to activate it.

Embodiments of the present invention are particularly applicable to the sensing of overheating of a plurality of electrical components, with the heat transfer module being suitable for mounting at or near the plurality of electrical components. In this way, a single heat sensing module can be used to monitor for overheating at a plurality of electrical components.

Preferably, the heat sensing module is mountable above the heat transfer module. This is beneficial since heat rises from the heat transfer module to the heat sensing module, and moreover the heat transfer module will commonly be mounted above the electrical components to be monitored.

Preferably, the heat transfer module comprises a casing which partially encloses the heat conducting member. The casing inhibits (it is insulated to the appropriate voltage) the heat conducting element (which may be electrically conductive) from coming into contact with electrical components, which might otherwise cause a short. The casing may comprise an aperture in its lower face to expose the heat conducting element to heated air rising from below the heat transfer module, which is particularly beneficial where the heat transfer module is to be mounted above or to the top of a set of electrical components. The casing may comprise an aperture in its upper face to permit heat transfer from the heat conducting member to the heat sensing module mounted above it. The casing may comprise pre-formed structures facilitating the heat transfer module being cut to a desired length. In this way a heat transfer module which would be too long to mount in a desired location can be trimmed to an appropriate length at the time of installation. The casing may comprise two strips and two end caps for securing the end strips together about the heat conducting element, the strips and end caps forming a surround. The end cap both holds the two strips together about the heat conducting element and closes off an exposed end of the heat conducting element when the heat transfer module is cut to length.

The heat transfer module may comprise a pair of grooves extending along it, and the heat sensing module may comprise a pair of formations for engaging with the pair of grooves.

Preferably, the heat conducting element is a metal strip. Preferably, the metal strip comprises copper, or is a copper strip, since this is both inexpensive and an excellent conductor of heat.

The sensor apparatus may comprise a clip for mounting the heat transfer module to or near an electrical component. In this way, where appropriate the heat transfer module may be used without the heat transfer element, for example where only a single electrical component or a relatively small region is to be monitored, or in cases where there is insufficient room to mount the heat transfer element. The clip may be removably attachable to the heat transfer module. The clip may be shaped and dimensioned to engage with an electric cable, providing a convenient means of mounted the heat sensing module in a distribution box or the like (or other enclosures).

A plurality of heat sensing modules may be mounted to the heat transfer member at different positions along its length. It will be appreciated that the further heat has to travel along the heat transfer module, the longer it will take and/or the lower the temperature experienced at the heat sensing modules. Accordingly, it will sometimes be necessary to mount multiple heat sensing modules on a single heat transfer module. For example, in one implementation a single heat sensing module could be mounted at or near the middle of the length of a heat transfer module, while in another implementation two heat sensing modules could be mounted to a heat transfer module, one being positioned approximately one third of the way along the heat transfer module from one end and the other being positioned approximately one third of the way along the heat transfer module from its other end.

The electrical components being monitored may comprise one or more of a neutral bar, common feeder busbar, mains switch and line connections for fuses, MCB’s, RCD’s and RCBO’s in a distribution board or consumer unit.

The heat sensing module may comprise a housing containing the thermal switch and a pair of metal tracks which form the first and second terminals, the thermal switch mounted between the pair of metal tracks, activation of the thermal switch enabling electric current to flow across the thermal switch and between the first and second terminals.

According to the present invention, there is provided a sensor apparatus for sensing overheating, the apparatus comprising a plurality of heat sensing modules, each heat sensing module comprising a thermal switch connected between a first terminal and a second terminal, wherein the plurality of heat sensing modules are electrically connected to each other. Preferably, the heat sensing modules are for mounting at or near a plurality of electrical components. By providing the sensor apparatus in modular form with the modules being electrically connected together, flexible installation of the individual heat sensors (thermal switches) can be achieved (because the modules can be individually placed on, against or proximate the electrical components they are intended to monitor), while electrically the separate modules can be treated as a group, reducing wiring requirements compared with an arrangement in which completely separate sensors are utilised.

As a result of the modular design, the sensing apparatus is more wholesaler friendly, since one type of item (module) can be stocked, and combined with other modules to achieve specific requirements, rather than providing multiple different sensors of different shapes and geometries. Further, the modular system is inexpensive and of a 'fit-all' nature, making it easier and space saving for engineers to hold stock in their van. Due to its flexible nature, it can be fitted to many more applications within or external to a consumer unit or distribution board. In other words, the sensor apparatus may be used (for example) for monitoring overheating of other electrical components, or even overheating outside of the context of electrical components (for example fire detection). Also, each module can be individually suited to service the requirement of each detection point instead of a single common/shared actuation result system. Further, detection may not be required at all points within (for example) a distribution box, and the modular design allows for a detection point omission where detection is deemed unnecessary.

In one embodiment, the first terminals of the plurality of modules are electrically connected together on a common line. This embodiment may be implemented in a form in which the second terminals of the plurality of modules are electrically connected together on a common signal line, a fault notification signal being asserted on the common signal line if the thermal switch of any of the modules is activated. This effectively provides a notification externally that there is a fault detected by one or more of the modules (without identifying which). Alternatively, this embodiment may be implemented in a form in which the second terminals of the plurality of modules are electrically connected to respective different signal lines, a fault notification signal being asserted on a signal line if the thermal switch of the module electrically connected to that signal line is activated. This effectively provides a notification externally of which of the modules is detecting overheating.

In another embodiment, the first terminals of the plurality of modules are electrically connected together on an earth line. In one implementation of this embodiment, the second terminals are electrically connected together and to a mains switch for disconnecting the power to the plurality of electrical components if the thermal switch of any of the modules is activated. This effectively trips the power to all of the electrical components being monitored (for example an entire distribution board) if a fault is detected by one or more of the modules (that is, if a thermal switch activates) . In an alternative implementation of this embodiment, the second terminals of a first group of the modules are connected together and to a first mains switch for disconnecting the power to the electrical components being monitored by the first group of modules if the thermal switch of any of the modules of the first group is activated, and the second terminals of a second group of the modules are connected together and to a second mains switch for disconnecting the power to the electrical components being monitored by the second group of modules if the thermal switch of any of the modules of the second group is activated. This implementation, intended for handling a split load distribution board, effectively trips the power to a subset of the electrical components being monitored (for example half of a split load distribution board) if a fault is detected by one or more of the modules monitoring that subset. In yet another implementation of this embodiment, the second terminal of each module is electrically connected to an isolation device (for example an RCBO or similar device) for disconnecting the power to the electrical component being monitored by that module if the thermal switch of that module is activated. This embodiment effectively trips the power to only the electrical component being monitored by the module if a fault is detected by that module.

The electrical components being monitored may comprise one or more of a neutral bar, common feeder busbar, mains switch and line connections for fuses, MCB’s, RCD’s and RCBO’s in a distribution board or consumer unit. It will further be appreciated that non-electrical components could be monitored, or the modules instead provide to detect overheating in selected areas rather than of particular components.

Each module may comprise a housing containing the thermal switch and a pair of metal tracks which form the first and second terminals, the thermal switch being mounted between the pair of metal tracks, activation of the thermal switch enabling electric current to flow across the thermal switch and between the first and second terminals.

Alternatively, each module may comprise a printed circuit board bearing mounting pins or plug and/or socket components forming the first and second terminals, the thermal switch being mounted to the printed circuit board.

The electrical connections between the modules may be made using individual jumper wires and/or a loom of jumper wires and/or flex circuits such as (but not limited to) polyimide circuits. Alternatively, the modules may be mounted onto a ribbon cable. In some cases, both a ribbon cable and jumper wires/loom may be used. For example, the electrical connections relating to notification may be achieved using a ribbon, while those relating to isolation may be achieved using jumper cables.

In the case that a ribbon cable is used, this may comprise a plurality of plug or socket connectors distributed along its length, via which the modules can be electrically and mechanically connected to the ribbon cable.

In some embodiments, the modules are physically mounted on the electrical components which they are intended to monitor.

It will be appreciated that both the notification function and the isolation function could be achieved by a single module. For example, the module may comprise two thermal switches, the first and second terminals of the notification function being connected to one of the two thermal switches and the first and second terminals of the isolation function being connected to the other of the two thermal switches. The two thermal switches and their associated terminals are preferably electrically isolated from each other.

It will be appreciated that each terminal of each module may comprise one or more terminal connectors for connecting that terminal to a terminal of another connector or externally of the sensor apparatus.

It will be appreciated that the techniques relating to the electrical connectivity of the heat sensing modules, and the techniques relating to the heat transfer module and the methods of mounting the heat sensing modules with respect to the electrical components to be monitored, can be combined.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings where like parts are provided with corresponding reference numerals and in which:

Figure 1 schematically illustrates a distribution box containing electrical components and sensor modules;

Figures 2A and 2B schematically illustrate the wiring of sensor modules for fault notification;

Figures 3A and 3B schematically illustrate the wiring of sensor modules for isolation; Figure 4 schematically illustrates combined wiring for providing both fault notification and isolation;

Figure 5 schematically illustrates a sensor module;

Figures 6A and 6B schematically illustrate a ribbon based system;

Figure 7A, 7B, 7C and 7D schematically illustrate a heat sensing module used with a heat transfer module; and

Figures 8A and 8B schematically illustrate a heat sensing module with a detachable clip for mounting to electric cables.

Detailed Description

Referring to Figure 1, an electrical distribution box I consumer unit 1 is shown. The unit 1 comprises a number of electrical components 2 in the areas of a neutral bar 2a, phase/line 2b and bus bar 2c. The electrical components 2 may include (by way of non-limiting example) the neutral bar, common feeder bus bar, mains switch and line connections for fuses, MCBs (miniature circuit breakers), RCDs (residual current devices) and RCBOs (residual current breaker with overcurrent). Heat sensing modules 3 are provided at, on, adjacent or near various of the components 2. The heat sensing modules 3 may for example be mounted on the electrical components 2 by way of clips or similar. It will be appreciated that, for larger electrical components 2, multiple heat sensing modules 3 may be mounted on a single electrical component. The heat sensing modules 3 are electrically connected together in a chain by electrical connections 4, which may take the form of jumper cables/leads or a ribbon cable for example. A lead-in/out cable 5 is connected to the first heat sensing module 3 in the chain to carry an electrical signal from the chain of heat sensing modules 3 to a junction box (not shown) or other third party device (not shown) which will process the electrical signal, for example to display to a user an indication that overheating has been detected in the distribution box I consumer unit

1. The heat sensing units 3 each contain a thermal switch, usually in an open state, which switches to a closed state if the local temperature at the thermal switch exceeds a predetermined temperature, thereby permitting an electrical current to flow through the thermal switch. This flow of electrical current may serve as a notification of overheating, or may directly trip out electrical components as will be described subsequently. Various thermal switches may be used, such as the one described in W02006/125996 and implemented in WO2014/006356. In use, if one of the electrical components 2 overheats, the thermal switch of an adjacent heat sensing module 3 will be activated, closing the switch and permitting an electrical current to pass through it, causing an electrical signal to be transmitted through the lead in/out cable 5 and to an external device. The external device may then activate an alarm or display a visual indication of overheating. The thermal switches may work by monitoring (and reacting to) the local ambient (air) temperature, in which case they need only be located in the vicinity of the component being monitored, rather than being in direct physical contact.

Referring to Figure 2A, an example of how a chain of heat sensing modules 3 can be provided in a chain is shown, with wiring utilised for providing a notification of overheating. Each of the heat sensing modules 3 can be seen to comprise a thermal switch 32 which is mounted between a first terminal 34 and a second terminal 33. When the thermal switch 32 is activated due to the local temperature rising above a predetermined level, electrical current is permitted to pass between the first and second terminals 34, 33. Each of the terminals may take the form of an electric track on a printed circuit board (PCB) or an electrical contact. In either case, terminal connectors 37 (e.g. a pin, plug or other element to which a connection can be made) may be provided, for example as shown here at either end of the terminals 34, 33.

As can be seen in Figure 2A, the first terminal 34 of each module 3 is electrically connected to a common line 36. In particular, the modules 3 are daisy chained together, with the common line 36 being formed from the first terminals 34 of each module 3, and the electrical connections between the terminals 34 (made via the terminal connectors 37). Similarly, the second terminals 33 of the modules 3 are electrically connected together on a common signal line 35. Again, the modules 3 are daisy chained together, with the common signal line 35 being formed from the second terminals 33 of each module 3, and the electrical connections between the terminals 33 (made via the terminal connectors 37). In the event of the temperature rising high enough to activate one of the thermal switches 32, the activated thermal switch will close, thereby permitting an electric current to flow across it. This will permit the current to flow between the first and second terminals 34, 33 of the activated module, and thus between the common line 36 and the common signal line

35. This will be the case irrespective of which of the modules is activated. In this way, a fault notification signal is asserted on the common signal line if the thermal switch of any of the modules is activated.

Referring now to Figure 2B, an alternative arrangement of Figure 2A is provided in which individual notification is provided of exactly which of the heat sensing modules 3 has been activated due to local overheating. Like reference numerals have been used for parts which correspond between Figures 2A and 2B. Such parts have the same structure and function, and will not be repeated in the interests of brevity. The difference between the arrangement of Figures 2A and 2B is that in Figure 2B the second terminals 33 of the modules 3 are electrically connected to respective different signal lines 35a, 35b. As a result, when the thermal switch 32 of a particular module is activated, a fault notification signal is asserted on only that signal line connected to that particular module. It will be appreciated that there is thus an individual signal wire for each module. It will further be appreciated that while two modules are shown in Figures 2A and 2B, any number of modules may be provided.

Referring to Figure 3A, an example of how a chain of heat sensing modules 3’ can be provided in a chain is shown, with wiring utilised for isolating (at least) the overheating electrical components. Each of the heat sensing modules 3’ can be seen to comprise a thermal switch 42 which is mounted between a first terminal 43 and a second terminal 44. When the thermal switch 42 is activated due to the local temperature rising above a predetermined level, electrical current is permitted to pass between the first and second terminals 43, 44. Each of the terminals may take the form of an electric track on a printed circuit board (PCB) or an electrical contact.

In either case, terminal connectors 47 (e.g. a pin, plug or other element to which a connection can be made) may be provided, for example as shown here at either end of the terminals 43, 44. As can be seen in Figure 3A, the first terminal 43 of each module 3’ is electrically connected to an earth line 45. In particular, the modules 3’ are daisy chained together, with the earth line 45 being formed from the first terminals 43 of each module 3’, and the electrical connections between the terminals 43 (made via the terminal connectors 47). Similarly, the second terminals 44 of the modules 3’ are electrically connected together on a line 46, and to a live terminal of a mains switch 49 for disconnecting the power to the electrical components if the thermal switch if any of the modules 3’ is activated. Again, the modules 3’ are daisy chained together on the line 46, with the line 46 being formed from the second terminals 44 of each module 3’, and the electrical connections between the terminals io (made via the terminal connectors 47). In the event of the temperature rising high enough to activate one of the thermal switches 42, the activated thermal switch will close, thereby permitting an electric current to flow across it. This will permit the current to flow between the first and second terminals 43, 44 of the activated module, and thus between the earth line 45 and the line 46. This will be the case irrespective of which of the modules is activated. In this way, the mains switch 49 is triggered to trip I disconnected power from the electrical components being monitored by the modules 3’ if the thermal switch of any of the modules is activated. In a variant of this, the modules are provided in two (or more) groups. In this case, the second terminals 44 of a first group of the modules are connected together and to a first mains switch for disconnecting the power to the electrical components being monitored by the first group of modules if the thermal switch of any of the modules of the first group is activated. Similarly, the second terminals 44 of a second group of the modules are connected together and to a second mains switch for disconnecting the power to the electrical components being monitored by the second group of modules if the thermal switch of any of the modules of the second group is activated. In this way, a split load distribution board can be powered down in parts, with only the part subject to overheating being disconnected from its mains supply by the appropriate switch.

Referring now to Figure 3B, an alternative arrangement of Figure 3A is provided in which individual isolation of electrical components is provided, with only an electrical component being detected as overheating being deactivated due to local overheating. Like reference numerals have been used for parts which correspond between Figures 3A and 3B. Such parts have the same structure and function, and will not be repeated in the interests of brevity. The difference between the arrangement of Figures 3A and 3B is that in Figure 3B the second terminals 44 of the modules 3’ are electrically connected to respective different signal lines 46a, 46b, and then to a respective RCBO 48a, 48b. The RCBO receiving a signal on the signal line 46a or 46b deactivates in response to the signal. As a result, when the thermal switch 42 of a particular module is activated, a signal is asserted on only that signal line connected to that particular module. It will be appreciated that there is thus an individual signal wire for each module, which goes to the RCBO being monitored by that module.

While Figures 2A and 2B have been described separately from Figures 3A and 3B, in practice it may be beneficial in some cases for both notification functionality (the Figure 2A/2B arrangement) and isolation functionality (the Figure 3A/3B arrangement) to be provided by a single set of modules. Due to the nature of the wiring required, it is preferable that the module comprise two separate thermal switches, the first and second terminals of Figures 2A and/or 2B being connected to one of the two thermal switches and the first and second terminals of Figures 3A and 3B being connected to the other of the two thermal switches. The two thermal switches and their associated terminals are electrically isolated from each other, in order that they do not disturb each other’s function. Figure 4 shows an array of heat sensing modules 30 which have both notification and isolation functionality. In particular, each of the modules is electrically connected to a common earth line 32, and to individual live signal lines 34, permitting individual isolation of the electrical components being monitored (e.g. RCBOs) as explained with reference to Figure 3A. Each of the modules is also electrically connected to a common signal line 36, and to individual notification signal lines 38, permitting notification of a specific heat sending module which has detected overheating. As mentioned above, the lines 32 and 34 (and their respective thermal switches within the modules) are electrically isolated from the lines 36 and 38 (and their respective thermal switches within the modules). The modules 30 are shown adjacent in this case, and may in some examples be mechanically engageable. However, in general the modules are physically and in particular mechanically separate and only electrically connected.

Referring to Figure 5, an example heat sensing module 300 is shown. The module 300 comprises a housing 310 containing a thermal switch 320 (shown in dashed lines to indicate it is located internally of the housing, first and second terminals (not shown) and terminal connectors 332, 334, 336, 338. The terminal connectors 332, 334, 336, 338, which may either be contact pins (if the thermal switch is mounted to a PCB within the housing, in which case the contact pins will be mounted on the PCB and connected to thermal switch 320 via conductive tracks on the PCB), extensions of the first and second terminals (if the thermal switch is simply mounted within the housing and the terminals take the form of metal contacts which are in contact with the two sides of the thermal switch and which extend outside the housing to permit external connection) or plugs (which could either be PCB mounted, or mounted to said metal contacts). For example, in the case of metal contacts, a U shaped contact (not shown) could be used, with the base of the U extending within and along the housing past (and in contact with) the thermal switch, and the upright parts of the U forming the terminal connectors. In Figure 5, the terminal connectors 332 and 334 are electrically connected to one end 320a of the thermal switch by a track or metal contact, while the terminal connectors 336 and 338 are electrically connected to the other end 320b of the thermal switch by a track of metal contact. The module 300 can be electrically connected to other modules, or to external devices (for notification or isolation purposes as explained above) by connecting the terminal connectors 332, 334, 336, 338 using jumper/link cables, wires, looms or other connecting means. The terminal connectors may be replaced with plug/socket connectors if preferred in order to make connections easier, or a crimp could be used to secure a cable onto a terminal connector. It will be appreciated that it is beneficial that two terminal connectors be provided in respect of each terminal so that each module can be easily electrically connected to two other modules (obviously the first and last module in the array will only be connected to one other module). It will be appreciated that the structure of Figure 5 only provides for a single thermal switch and a single pair of terminals, while as explained in relation to Figure 4 two thermal switches and two pairs of terminals would generally be used in order to give effect to notification and isolation functions. If both functions were to be provided, the physical structure of Figure 5 could be duplicated. In such a case a PCB based solution may be beneficial.

Referring to Figures 6A and 6B, an implementation in which the modules are electrically connected (at least in part) by a ribbon cable is shown. In Figure 6A, a sensor apparatus for use at a neutral bar of a distribution board is shown. The sensor apparatus comprises a first heat sensing module 3000a and a second heat sensing module 3000b. The heat sensing modules 3000a and 3000b may be identical, and as described above. In practice a greater number of modules may be used, but only two are shown here in the interests of simplicity. The modules are electrically connected together via a ribbon cable 3050. In addition, the modules may be mechanically connected to the ribbon cable 3050, in which case the ribbon cable 3050 also serves as a support for the modules. Such a mechanical connection could be achieved by way of adhesives or clip, or alternatively a plug and socket arrangement could be provided whereby (for example) a series of sockets are arranged along the ribbon cable 3050, into which a plug (for example) mounted on the modules can be inserted. In this case, the plug/socket arrangement would provide both an electrical and mechanical connection between the ribbon cable 3050 and the modules 3000, and would also permit easy connection/disconnection of the modules for installation and replacement purposes. If fewer modules are required than the number of plugs or sockets on the ribbon, then certain plugs/sockets on the ribbon could be left without a module (a cap may be required instead). Also connected to the ribbon cable 3050 are plugs 3010 which is provided in order to enable the ribbon of the sensor apparatus to be joined to another ribbon and/or a take on connector which connects via a wire to a junction box or other device where a notification signal from the ribbon cable can be received. The ribbon cable 3050 comprises in this case signal cores (shown with solid lines) which correspond to the lines 35a, 35b in Figure 2B, and a common earth (shown with a dashed line) which corresponds to the line 36 in Figures 2B. It will be appreciated that only two cores are shown here, corresponding to the signal outputs (for notification) from the two modules, but if a greater number of modules are used then a greater number of cores are required for individual notification. The ribbon cable 3050 may bear only some of the electrical connections. For example, the ribbon cable 3050 may bear the signal lines relating to notification, while those relating to isolation (that is, the wiring shown in Figures 3A and 3B) may be achieved by way of separate wires. However, it is also possible for the ribbon cable to carry signals relating to isolation.

Referring to Figure 6B, a further ribbon for connection to the line portion of the distribution box is shown. Here, only two modules 4000a and 4000b are shown for clarity, but in practice a larger number of modules (for example 10) may be provided on the same ribbon 4050. As with Figure 6A, external connections to other ribbons are made via plugs 4010. The structure of the ribbon based assembly of Figure 6B is substantially the same as that of Figure 6A, and thus description thereof will not be repeated here.

Referring to Figure 7A, a heat sensing module 72 is shown mounted to be mounted to a upper side of a heat transfer module 74. The heat sensing module 72 may be substantially the same as any of the heat transfer modules 3, 3’, 30, 300, 3000 or 4000a, 4000b as described above. The heat transfer module 74 may be placed adjacent to or onto a linearly arranged set of electrical connections, such as the connections 2a, 2b or 2c shown in Figure 1. For example, a heat transfer module 74 may be mounted on top of (or above) the left hand grouping of electrical components (MCBs and RCDs) 2 shown in Figure 1, and a second heat transfer module 74 may be mounted on top of (or above) the right hand grouping of electrical components (MCBs and RCDs) 2 shown in Figure 1. Heat generated by the electrical components 2 will then be transferred to the heat transfer module 74 by conduction (if the heat transfer module 74 is physically touching the housing of the electrical components), convection (hot air carrying heat from the components 2 to the underside of the heat transfer module 74 if there is a gap) and radiation. If an electrical component located anywhere along the heat transfer module 74 should overheat, it will raise the temperature at that part of the heat transfer module 74.

The heat transfer module 74 comprises a heat conducting member 78 which is mounted within a non-electrically conducting housing 79 of the module 74. The heat conducting member 78 may be metal, for example copper. The housing 79 surrounds the heat conducting member 78 to reduce the risk of the copper causing a short circuit to the electrical components (although this should be a low risk anyway since all electrical components are themselves typically housed within a casing within a distribution box for example). If the temperature at any point along the heat transfer module 74 should be raised, the heat will conduct along the heat conducting member 78, eventually reaching the heat sensing module 76 mounted elsewhere along the heat transfer module 74. The resulting temperature increase at the heat sensing module 76 will then cause the thermal switch of that module to activate should the temperature increase above a threshold activation level.

It can be seen from Figure 7A that there is an aperture 81 in the upper face of the heat transfer module 74, leaving the upper side of the copper member substantially exposed. This permits heat transfer from the heat conducting element 78 to the heat sensing module 76 which is mounted above it. Referring to Figure 7B, which shows the lower side of the heat transfer module 74, it can be seen that there is an aperture 82 in the lower face of the heat transfer module 74, leaving the lower side of the copper member substantially exposed. This permits heat transfer from the monitored electrical components to the heat conducting element 78. From both Figures 7A and 7B it can be seen that there are pre-formed structures 83 at intervals along the heat transfer module 74 which make it easier for the heat transfer module 74 to be cut to length (the formations form a weak point to cut through, and also serve as a guide for a hacksaw or the like). Also provided on the heat transfer module 74 are grooves 84, into which projections 85 on the heat sensing module 76 are able to engage to mount the heat sensing module 76 to and above the heat transfer module 74.

In Figure 7A and 7B, a single heat sensing module 76 is provided on the heat transfer module 74. The heat sensing module 76 may be electrically connected to other modules in the manner described with reference to Figures 1 to 6 above, the other modules themselves being mounted to respective heat transfer modules, or alternatively mounted without heat transfer modules, for example in the manner which will be described below with reference to Figures 8A and 8B. In contrast, in Figures 7C and 7D a plurality of heat sensing modules 76a-e are provided on a heat sensing module 74’. These may be electrically connected together in the manner described above with reference to Figures 1 to 6. In Figure 7C and 7D, the projections (arms) 85 of the heat sensing module 76, and how they engage with the grooves 84 of the heat transfer module 74, can be seen more clearly. In particular, it will be appreciated that the heat sensing module 76 may be pressed downwardly onto the top of the heat transfer module 74 so that the arms 85 are urged apart and then snap into the grooves 84 to secure the heat sensing module 76 in place. It will be appreciated that the heat sensing module 76 can then be slid along the grooves 84 into a desired position, and can be removed if required by being slid entirely along and off the end of the heat transfer module 74. In other words, the heat sensing module 76 may be mechanically engaged with the heat transfer module 74.

Also shown in Figures 7C and 7D is a clip mounting slot 86 in the heat sensing module 76 permitting a clip to be mounted thereto as will be described below with reference to Figure 8A and 8B. A slot may be provided in two opposite sides of the module. Finally, brackets 87 are shown to be mounted to the heat transfer module 74, which can be used to mount the heat transfer module 74 in place with respect to the electrical connections to be monitored. For example, projections 87a on the brackets 87 may clip into apertures in the housing for the electrical components.

The brackets 87 are in the present implementation engaged with the grooves 84, but it will be understood that alternative mounting structures are also possible.

As a variation of the structure shown in Figures 7A to 7D, the heat transfer module 74 could itself be modular, comprising two elongate strips and two end caps. The elongate strips and the heat conducting element 78 could be cut to a desired length and the elongate strips mounted along the sides of the heat conducting element 78. Then, the end caps serve to secure the elongate strips in place and to cover the end portions of the heat conducting element 78.

Referring now to Figures 8A and 8B, a mounting clip 90 is shown to have a projecting part 91 which is engageable with the slot 86 on a heat sensing module 76. The mounting clip 90 is a single piece element comprising a cable engagement part 90a and a resiliently biased part 90b. In its equilibrium state the resiliently biased part 90b retains the cable engagement part 90a in a closed position as shown in the Figures, in which a cable (not shown) can be located and held within the cable engagement part 90a to secure the heat sensing module 76 to the cable. When the two halves of the resiliently biased part 90b are pressed together, the cable engagement part 90a opens up, to permit a cable to be removed from or placed into the engagement part 90a. Then, when the pressure is released the resilient bias of the part 90b causes the engagement part 90a to close again.

It will be appreciated from Figures 7 and 8 that a given heat sensing module can either be secured in place and used with a heat transfer module 74 to monitor a large area/a relatively larger number of electrical components or can be secured in place and used without a heat transfer module to monitor a small area/a relatively smaller number of electrical components.

Claims

1. A sensor apparatus for sensing overheating, the apparatus comprising a heat sensing module and a heat transfer module, the heat transfer module comprising an elongate heat conducting member, and the heat sensing module being mountable to the heat transfer module and comprising a thermal switch which switches when the ambient temperature at the heat transfer module exceeds a threshold temperature.

2. A sensor apparatus according to claim 1, wherein the apparatus is for sensing overheating of a plurality of electrical components, and wherein the heat transfer module is for mounting at or near the plurality of electrical components.

3. A sensor apparatus according to claim 1 or claim 2, wherein the heat sensing module is mountable above the heat transfer module.

4. A sensor apparatus according to any preceding claim, wherein the heat transfer module comprises a casing which partially encloses the heat conducting member.

5. A sensor apparatus according to claim 4, wherein the casing comprises an aperture in its lower face to expose the heat conducting element to heated air rising from below the heat transfer module.

6. A sensor apparatus according to claim 4 or claim 5, wherein the casing comprises an aperture in its upper face to permit heat transfer from the heat conducting member to the heat sensing module mounted above it.

7. A sensor apparatus according to any one of claims 4 to 6, wherein the casing comprises pre-formed structures facilitating the heat transfer module being cut to a desired length.

8. A sensor apparatus according to any one of claims 4 to 7, wherein the casing comprises two strips and two end caps for securing the end strips together about the heat conducting element, the strips and end caps forming a surround.

9. A sensor apparatus according to any preceding claim, wherein the heat transfer module comprises a pair of grooves extending along it, and wherein the heat sensing module comprises a pair of formations for engaging with the pair of grooves.

10. A sensor apparatus according to any preceding claim, wherein the heat conducting element is a metal strip.

11 .A sensor apparatus according to claim 10, wherein the metal strip comprises copper.

12. A sensor apparatus according to claim 2, comprising a clip for mounting the heat transfer module to or near an electrical component.

13. A sensor apparatus according to claim 12, wherein the clip is removably attachable to the heat transfer module.

14. A sensor apparatus according to claim 13 or claim 14, wherein the clip is shaped and dimensioned to engage with an electric cable.

15. A sensor apparatus according to any preceding claim, wherein a plurality of heat sensing modules are mounted to the heat transfer member at different positions along its length.

16. A sensor apparatus according to claim 2, wherein the electrical components being monitored comprise one or more of a neutral bar, common feeder busbar, mains switch and line connections for fuses, MCB’s, RCD’s and RCBO’s in a distribution board or consumer unit.

17. A sensor apparatus according to any preceding claim, wherein the heat sensing module comprises a housing containing the thermal switch and a pair of metal tracks which form the first and second terminals, the thermal switch mounted between the pair of metal tracks, activation of the thermal switch enabling electric current to flow across the thermal switch and between the first and second terminals.

18. A sensor apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Intellectual

Property

Office

Application No: GB1700506.7