Pool Sectn 29 Regulation 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Improvements in or relating to electrical distribution boards The following statement is a full description of this invention, including the best method of performing It known to us: P111ABAU/1207 1 Improvements in or relating to Electrical Distribution Boards BACKGROUND The present invention relates to an electrical distribution board assembly. 5 An electrical distribution board distributes electrical power from one or more incoming power supply terminals to a number of outgoing power supply terminals. Typically, the electrical distribution board is a housing which comprises a number of circuit breakers. 10 Present building regulations require users of electricity in small, medium and large commercial and industrial buildings to be able to identify their energy usage. Moreover, the building regulations state that it is reasonable for the end user to identify 90% of the energy usage of their building(s). It is also reasonable for the 15 end-user to be able to identify where the energy is being used, e.g. sub-metering of power, lighting circuits etc. Conventional practice for monitoring electrical energy usage is to retrofit a commercially available electricity meter and transformer combination to the 20 distribution board. This can be placed around the incoming power cables to the distribution board, or the outgoing power cables from the distribution board to the load. Alternatively, such electricity meter and transformer combinations may be installed within the distribution board as part of a new installation. 25 While this practice is effective at accurately monitoring the energy usage of the distribution board, it is limited in that it is only possible to monitor the total energy usage of the distribution board. If a user wishes to identify the energy usage of particular circuits of the distribution board they are 2 required to add an electricity meter and transformer combination to each of the individual outgoing power circuits. This may be more detailed than the user needs, and is of course expensive. Alternatively, a number of distribution boards 5 each having an energy metering facility at their incoming side are connected together. This results in a complicated system which is expensive and time consuming to install. It would be desirable to provide for more economic metering of groups of circuits 10 in an electrical installation. SUMMARY OF THE INVENTION In light of the above, according to a first aspect of the present invention, there is provided an electrical distribution board assembly comprising: 15 a chassis; at least one incoming terminal; at least one bus conductor extending along said chassis for distributing electrical power from said incoming terminal to an array of outgoing conductor terminals; 20 wherein said array of outgoing conductor terminals is subdivided into at least two sub-arrays, said bus conductor providing a metering point between said sub-arrays. The provision of a metering point between sub-arrays allows for monitoring 25 power consumption in one group of outgoing circuits separately from another, without unduly increasing the size or cost of the installation. Preferably, said bus conductor is a busbar. 30 The assembly may be provided with a sensing device at said metering point, the sensing device in use providing a metering signal to a metering device. S:\patricia\cases\2\29899\AU\00\20111004-Desc & claims-AMENDED PAGES 901338.doc\\ 3 The sensing :device may be a current transformer encircling said bus conductor at the metering point The sensing devices may be a current transformer in dlose proximity to said 5 bus conductotat the-metering point. The coupling of the sensing device to the bus-conductor Is by electromagnetic induction* in that case rather than by eledtrical obritact The current transformer may comprise a body having a perture (or 10 passage of the bus conductor. The assembly may fUrther comprise at least one additional sensing device at a metering point associated With said' incoming terminal, the additional sensing device in use providing a second metering signal to a metering i5 device, whereby energy consumption of the whole array and a sub-array can be metered simultaneously; In a preferred embodiment, said electrical distribution board assembly comprises a plurality of incoming terminals and a plurality of bus. 20 conductOrs extending in parallel along said chassis for distributing multi phase electrical power from said incoming tertrinals to said array of outgoing conductor terminals, and each busbar provides ^a metering point between said sub-arrays. 25 Preferably, each bus conductor is a busbar. The assembly rmay be providedwith a respectiVe sensing deVice coupled to each bus conductor at said metering point, the sensing devices in 0se providing a metering signal to a metering device. 30 4 The. sensing devices may be current transformers encircling their respective bus conductors atthe metering point. The bus conductors at the metering point may be. spaceqd more widely 5 than within the sub-arrays. This will provide space for mounting of a current transformer or other sensing device, for example- without unduly increasing the size of the whdle assembly. Where the bus conductorsare but bars, tt liastone ofsaid bus bars rmay 10 be made in sections, joined together between the sub-arrays. In one. embodiment, each bus bar is made in three-sections, Qomprising a straight section within, each of said sub-arrays and a joining section connecting the two straight sections together between the sub-arrays. 15 In a three-phase embodiment, the joining sections of two bus bars are curved to increase spacing between the joining sections relative to de straight sections. thereby to provide said metering point. The assembly may further comprise -a metering device: connected to 20 receive said sensing signal from -the sensing device and to provide a readout of energy consumption in one or more of said sub-arrays of bufgoing circuits. 'In a preferred embodiment the metering device is located in -a metering 25 unit on a separate chassis adapted for mounting beside the distribution board assembly chassis and connected to receive said metering signal from the sensing device(s) coupled to the bus conductor(s) at said metering pointss.
5 The metering unit may comprise an additional metering device for receiving sensing signals from a sensing device associated with the incoming terminals. Said electrical distribution board assembly may be adapted such that it is 5 electrically connectable to another similar electrical distribution board assembly. This permits a modular expansion of the distribution board to suit a larger electrical installation. Preferably, each electrical distribution board assembly is electrically connected 10 by one or more busbars extending along said chassis. According to a second aspect of the present invention there is provided an electrical distribution board comprising: at least one electrical distribution board assembly according to the first aspect; 15 a first electrical energy metering system coupled to the bus conductor between said sub-arrays of said at least one electrical distribution board assembly; and a second electrical energy metering system coupled to said incoming terminal(s). 20 Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups 25 thereof. S:\patricia\cases\2\29899\AU\00\20111004-Desc & claims-AMENDED PAGES 901338.doc\\ 6 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described, by way of example oniy. wItht reference to the accompanying drawings, in which; .5 Fig. 1 is a perspective view of an electrical distribution board comprising ar electrical distribution board assembly according to a first aspect of the present invention, together^with associated netering unit,. 10 Fig- 2 is atop view of the distribution board of Fig. 1.; Fig. 5 is an enlarged view ofthe busbars and cuirent'transformers Of Fig,; 1 at a metering point between sections of the distribution board; and 15 Fig. 4 is' an enlarged view of the electrical metering devices of the Metering unit in Fig. 1.
7 DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Figs. i and 2 illustrate an electrical distribution board I which includesran -electrical distribution board assembly 10 comprising a chassis 12(in the 5 form of a chassis pan assembly), three incomingterirrInals i4a-14b,. three busbars 16a-6b (an -example of a bus conductor) and an array of outgoing conductor terminals 18. A metering unit to be described later, is provided ori a separate chassis 34 (in, the form of a chassis pan assembly). 10 The chassis pan assembly 12 is a plastics moulding pr formed metal chassis, in the general form of a rectangular board which is adapted to be mounted on a wall or rack via mounting points 20. Cover and outer housing paits may also be provided, though these are not part of the 15 invention and hot shown. The incoming terminals 14a-14b are located towards the bottom of the chassis pan assembly 12. Although three-Incoming terminals 14a-44b are illustrated in Figs, I and 2. for an assembly IQ supplying three-phase 20 power, it should be appreciated that the assembly 10 may comprise one, two, four or more incoming terminals. depending on the required type of power supply. A neutral. terminal is also shown, iIn this example. In the installed state, individual conductors (cables) which are not shown in. the drawing will lead power into the terminals 14a-14c. 25 Within the distribution board assembly, busbars I 6a- 6b extend along the length of the chassis pan assembly 12. The busbars 16a-16b distribute electrical power from the incoming terminals 14a-14b to the array of outgoing conductor terminals 18. Again, although three busbars 16a-16b 30 are illustrated in Figs. 1 and 2, it should be appreciated that-the number of 8 busbars. will correspond to the number of incoming terminals explained above. The outgoing conductor terminals 18 are adapted to feed miniature circuit S- breaker devices 23 mounted qn DIN or similar mounting Fqils '22. The miniature circuit: breaker devices 23 may be simple. switches, but are tyltially currentesensitive circuit breaker devices. Atn outgoing terminal of each miniature circuit breakersis available for tife connection of a cable to carry power out to :an individual load circuit within the wider installation. 10 Each terminal 18 is conriectable to- a respective one of said busbars 16a i6c, by operation of a switch 23. In this way, the unused terminals 18 are not live,, only the ones connected into a miniature'circuit breaker 24 In the three-phase example shown, the outgoing terminals 18 of each sub-array are connected to the three phases in a repeating sequence. Aset of three 15 adjacent miniature circuit breakers 24 will thus receive a full set of three phases. Such arrangements, and variations thereof, arewell known in the field and no further description is given here. In contrast. to conventional 20 arrangements, however, the array. of outgoing conductor terminals 18 in this example is split into afrst sub-array 26a ard a second sub-artay 26b. As illustrated in Fig. 3, the. busbars i6a-16b are exposed in the space; between sub-arrays 26a, 26b. The. bus bars are also splayed outwardly in 25 this region to increase their spacing and define a metering point 28 between the two sub-array -26a, 26b. The metering point 28 allows for monitoring power consumption in outgoing circuits connected to one sub abrey separately from the other, without undulyincreasing the size or cost of the installation. 30 9 In the embodiment illustrated here, the;assembly 10 is shown with sensing -devices in the form of three. current transformers 3Q ,ipcumferentially mounted around their respective busbars 16f-1t6b at the, meterdng point. To facilitate assembly, and to maximize sharing of components with other 5 product lines. each. of the busbars in this example is made in three sections: two straight sections extending within the respective sub-arrays, and a joining section connected between the other sections by a bolted or riveted connection. The current transformets can be fitted to tese. joining sections. before final assembly into the distribution boani. One or more of 10 the joining sections may provide the splaying necessary to providespace for the current trailsfonters. An insulating cover (not shown) will be provided over the metering point, to prevent accidental contact with the live conductors. 15 As illustrated best in Fig. 4, two digital nietering devices 32a and 32bi are mounted together with a second set of current transformers 36 on a second chassis pan assembly 34. The second chassis pan assembly with these components comprises a metering sub-assembly or module, which can: be.supplied as a separate unit for use lith the novel distribution board 20 assembly provided on chassis pan assembly 12. In the finished installation, incoming cables pass over the chassis pn assembly :34 and through the-second sets of:current transformers 36. Each electrical meter 32a, 82b is connected to receive metering signals 25 from the current transfdrmers 30 and 36, respectively. The loWer set of current transformers 36 meter the total poWer consumption of both sub arrays 26a, 26b, and hence meter 32b records the total consumption of all outgoing circuits connected to the terminals 18 in the distribution board. This part of the arrangement is conventional. At the same fime, however, 30. upper current transformers 30 meter the power consumption of the 10 outgoing circuits connected to terminals of the Lpper sub-array 26a only. A simple subtraction.of the Upper power consumption fromi the total. p6Wer consumption' dives ihe power consumption: of'the lower sub-array 266, so that the- user can know not only his total energy usage, butialso the usage 5 of each group circuits. By connecting only the lighting circuits to the upper sub-array 26a, for example, the meter 32a will tell how much energy is consumed for lighting FUrthermore, although only, the elecfhical distributidh board 1 has bee 10 illustrated as compising only one assembly 10, it should be appreciated that any suitable number of assemblies 10 may be included irran electrical distribution board 1.. For example, each assembly 1.0 fs adapted such: that it Is electrically connectable to another similar assembly 1. Each assembly may be connected by simply connecting together busbars 16 15 16b. Therefore, it is possible to monitor a large number of sub-arrays by simply including the feqUired nUmber of assemblies 10 in the distribUtion board i. This avoids 'an unneitessarly complex system, which is also less expensive than previous options. If desired, an assembly- 10 can be made with three or more subsets of outgoing terminals, and two metering 26 points between them. Modifications and improvements 'may be. made to the above without departing from the.spirit and scope of the present invention. For example, although current transformers; 30 'have been described ;and illustrated 25 above for monitoring the power consumption, it should be appreciated that Other sensing devices, whether of contact or non-contact 'type, may be employed. Also, although the above assembly 10 has been illustrated and described 30 as a three-phase power supply; it should be appreciated that the assembly 11 10 could equally operate with a single-phase, two-phase, or poly-phase power supply. In the metering arrangements, two simple meters 32a. Z2b are illustrated, 5 each connected to its own sensing device jn the form: of the current transformers 30, 36. In other embodiments a single metering device may provide Multiple channels, which can be read out sequentiallyy. A more sophisticated rmtering device could even be configured to perform the subtraction mentioned above. 10 Furthermore, although the current transformers 3O, 36, have. been illustrated and described above as being discrete independent devices it should be appreciated that the current transformers 30, 36 may be in the form of a' single device which comrdses three 'apertures Which are 15 adapted to receive the busbars 16a-16b. The operation of the single device remains the same as the discrete independent devices. Also, although the metering device has been described above as providing a readout of energy 'consumption, it should be appreciated that the meter 20 may readout, other characteristics such as amps, voltage, power factor, which may be sensed by the device.