GB2559391A

GB2559391A - Bus bar assembly

Info

Publication number: GB2559391A
Application number: GB1701840.9A
Authority: GB
Inventors: Simon Clegg Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-02-03
Filing date: 2017-02-03
Publication date: 2018-08-08
Also published as: GB201701840D0

Abstract

A bus bar assembly for a power distribution board of an electrical wiring system comprises a bus bar 100, having a conductive spine with a plurality of conductive elongate fingers 102 extending, in parallel and spaced apart relation, from at least one edge thereof, each finger having a distal end configured to be inserted into a respective live input terminal of an MCB 106; wherein a current transformer 104 is mounted over at least one of said fingers between its distal end and said spine and is communicably coupled to a data collection unit 206 including data transmission means 110, 112 configured to transmit data representative of a current transformer output to a control module 200.

Description

(71) Applicant(s):

Andrew Simon Clegg

Priestlay House, Chapel Lane, Nottswood Hill, Longhope, Gloucestershire, GL17 0ΑΝ,

United Kingdom (72) Inventor(s):

Andrew Simon Clegg (56) Documents Cited:

EP 2408073 A1 WO 2015/055261 A1 JP 2014027710 A US 20150207309 A1

WO 2015/068333 A1 WO 2008/065904 A1 JP 2014027709 A US 20120327563 A1 (58) Field of Search:

INT CLH01R, H02B Other: Online: WPI, EPODOC (74) Agent and/or Address for Service:

Wynne-Jones, Laine & James Ltd

Essex Place, 22 Rodney Road, CHELTENHAM,

Gloucestershire, GL50 1JJ, United Kingdom (54) Title of the Invention: Bus bar assembly Abstract Title: Bus bar assembly (57) A bus bar assembly for a power distribution board of an electrical wiring system comprises a bus bar 100, having a conductive spine with a plurality of conductive elongate fingers 102 extending, in parallel and spaced apart relation, from at least one edge thereof, each finger having a distal end configured to be inserted into a respective live input terminal of an MCB 106; wherein a current transformer 104 is mounted over at least one of said fingers between its distal end and said spine and is communicably coupled to a data collection unit 206 including data transmission means 110, 112 configured to transmit data representative of a current transformer output to a control module 200.

FIG. 3

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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FIG.1 (Prior Art)

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FIG.2 (Prior Art)

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FIG. 3

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102

104

108

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116

FIG.4

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FIG. 5

BUS BAR ASSEMBLY

This invention relates generally to a bus bar assembly for an electrical distribution box or consumer unit and more particularly, to a bus bar assembly for use with a current transformer device for improved installation of a multi-channel smart meter in an industrial distribution box or domestic consumer unit.

Smart metering is becoming increasingly widespread, with green initiatives resulting in increasing numbers of smart meters being installed in people’s homes, and industrial environments every year. A smart meter is configured to take periodic measurements of the power being drawn by whichever power distribution box or consumer unit to which it is installed. This measurement data can then be processed and wirelessly transmitted to a user interface for the energy company and/or a home owner/bill payer to provide accurate data on power usage. This reduces the need for predictive bills and also allows the home owner/bill payer to analyse their own energy usage and determined where they can save energy.

One known type of smart meters takes a measure of the current being drawn, using an ammeter, and then uses algorithms to calculate the power. Power distribution boards typically carry a high current, which is then split and distributed out through the respective circuits in the wiring system. As a result, the current is typically too high to be measured by the ammeter without causing damage. Therefore, it is common to use current transformers (CTs) to reduce the current at each circuit output or “channel” to a measurable level. Typically, the current can be reduced using a CT, to as little as 1/3,000^th of its original level. Voltage is also measured (at high sample rate e.g. 1000/sec) with a high accuracy A-D converter (typically 21 bit Sigma-Delta). The waveform of both is used to calculate ‘true Power’, Power Factor, etc. The calculations are done in a microprocessor with suitable algorithms. This data, once measured and calculated will result in an accurate value for true power in kWh rather than simple kVA which is simple multiplication of Volts*Amps..

There are problems associated with the use of CTs in power distribution boards, such as those used in industrial distribution boxes and domestic consumer units

Referring to Figure 1 of the drawings, in one known method of installing the CTs, so-called split-core CTs 10a are clipped around the circuit cable 12 at the output of each MCB 12a, and larger split-core CTs 10b are clipped around the feed cables 14. Such split-core CTs are considered advantageous in that they can be installed retrospectively in a pre-existing wiring system. However, the CTs tend to be bulky and add more congestion into what is usually an already congested cable area. Each CT must be installed individually, and movement of the cables 12, 14 themselves, for example when an electrician is doing work on the power distribution board 16, can easily dislodge the split-core CTs such that they become loose or fall off entirely, resulting in faulty data and therefore incorrect smart metering. Each split core CT must have its own pair of conductors 18 which then feed back to the monitoring equipment of the smart meter, thus contributing further wiring which can make the cable area messy, confusing and over-congested.

Referring to Figure 2, another known method is to use current transformer strips 20, or CT strips. A CT strip includes a plurality of CTs 10 within a strip 20 which are spaced apart at the same distance as the miniature circuit breakers (MCBs) 22 of the power distribution board 16, and are installed on the cables 12, adjacent to, and at the outputs of, the MCBs. Thus, whilst the CTs can be installed in a single operation, changing the MCBs 22 is complicated by the presence of the strips 20. Furthermore, CT strips 20 are complicated to fit and can, therefore, be expensive. The cables 14 on which the CT strips 20 are to be installed must be removed and re-inserted. Additionally, in order for the strip 20 to work, it must have all of its CTs 10 around a cable. Therefore this is only a useful solution if the number of cables 14 is a multiple of the minimum strip length.

Yet another known solution is to use solid core CTs, which are cheaper and simpler than the split-core CTs referenced above. However as the induction core is a solid ring installation thereof requires that the wires at the output of each MCB be disconnected and fed through the CT before being re-connected. Therefore, they can be complicated and expensive to install retrospectively. Even if they have been fitted at the same time as a new power distribution board, the same problems arise if a CT is faulty and needs to be replaced.

Whether these solutions are provided on 3-phase (industrial distribution boxes) or 1-phase (domestic consumer unit) power distribution boards, the above mentioned issues are much the same.

It would be desirable, therefore, to provide an assembly that enables a desired number of CTs to be quickly and easily installed in respect of a power distribution board, whether initially or retrospectively, and aspects of the present invention seek to address at least some of the issues mentioned above. According to a first aspect of the present invention, there is provided a bus bar assembly for a power distribution board of an electrical wiring system, the assembly comprising a bus bar, having a conductive spine with a plurality of conductive elongate fingers extending, in parallel and spaced apart relation, from at least one edge thereof, each finger having a distal end configured to be inserted into a respective live input terminal of an MCB; wherein a current transformer is mounted over at least one of said fingers between its distal end and said spine and communicably coupled to a data collection unit including data transmission means for configured to transmitting data representative of a current transformer output to a control module.

According to one exemplary embodiment of the present invention, the data collection unit may comprise a printed circuit board on which there may be provided an analogue to digital converter configured to sample current signals from at least one current transformer. Optionally, the data transmission means may comprise hard wired connection between said data collection unit and said control module.

Optionally, according to one exemplary embodiment of the present invention, each of a plurality of the fingers may have a respective current transformer mounted thereon.

In one exemplary embodiment of the present invention, the or each current transformer may have a solid ferrite core, with primary and secondary conductors. The primary conductor of the or each current transformer may be the respective finger of the bus bar on which it is mounted, and the secondary conductor of the or each current transformer may comprise a wire. The wire may be wrapped around the ferrite core a plurality of times.

According to an exemplary embodiment, the data collection unit may comprise a printed circuit board, which may incorporate an analogue to digital converter configured to sample current signals from at least one current transformer, and the two distal ends of wire may be mounted on, or otherwise electrically coupled to, the printed circuit board. Optionally, the data transmission means may comprise a modular connector connected to the printed circuit board and connected by means of a communications cable to the control module, so as to enable transmission of data representative of a current transformer output thereto.

Optionally, the printed circuit board may further comprise a modular connector which may be communicably coupled to the control module and configured to transmit data representative of a current transformer output thereto. Whilst the assembly may include a bespoke control module, it will be apparent to a person skilled in the art that the invention of a bus bar assembly comprising a bus bar, having a conductive spine with a plurality of conductive elongate fingers, a current transformer and a connector may be affixed to any pre-existing control module as is known in the art.

According to one exemplary embodiment of the present invention, the bus bar assembly may include a control module, wherein data representative of the current in the or each finger may be sent, via the connector, to the control module. The control module may include a processing module configured to apply algorithms to the data, in order to obtain data representative of the power used at the or each finger.

In one exemplary embodiment the control module may include a communications module, which may comprise a wireless communications device, configured to communicate said power data wirelessly to a remote server or database to be stored.

Optionally, the control module may be connected to said bus bar and configured to be powered thereby.

According to one exemplary embodiment of the present invention, the or each current transformer may be a solid core current transformer having an aperture therethrough and may be configured to be mounted on a respective finger of the bus bar by inserting the finger through the aperture.

Optionally, the or each current transformer may be a split core current transformer configured to be clipped onto a respective finger of the bus bar.

According to a further aspect of the present invention there is provided, a method of installing a power distribution board, comprising providing a DIN rail, connecting a main switch to a power supply and mounting said main switch to said DIN rail, mounting a plurality of MCBs at locations along said DIN rail, providing a bus bar assembly substantially as described above, and inserting a distal end of each of a plurality of said fingers of said bus bar into the live input terminal of a respective MCB.

These and other aspects of the present invention will be apparent from the following specific description, in which embodiments of the present invention are described by way of examples only, and with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of a 3-phase installation power distribution board illustrating a first known method of installing CTs;

Figure 2 is a schematic diagram of a 1-phase installation power distribution board illustrating a second known method of installing CTs;

Figure 3 is a schematic front-view of a bus bar assembly according to an exemplary embodiment of the present invention;

Figure 4 is a schematic plan view of the bus bar of Figure 3; and

Figure 5 is a schematic front view of a domestic power distribution board incorporating the bus bar assembly of Figure 3.

Referring to Figure 3 of the drawings, a bus bar assembly according to an exemplary embodiment of the present invention comprises a bus bar 100 comprising twelve equally spaced fingers 102. The bus bar 100 may be one such as those known in the art, and is typically made from electrical grade copper. In the exemplary embodiment illustrated, the fingers 102 are 5mm in width, and spaced apart by 18mm. This is currently standard in the art, however any suitable bus bar configuration may be used and the invention is not necessarily intended to be limited in this regard. A solid core current transformer (CT) 104 is fitted to each finger, close to the base of the bus bar 100. Solid core CTs 104 are more reliable as they do not depend on the magnetic connectivity through any air gaps, as in splitcore CTs. However, split-core transformers could alternatively be used. Each CT 104 can therefore take a current measurement in respect of each finger 102. With the CTs 104 fitters over each finger and resting against or close to the elongate base or spine of the bus bar 100, the bus bar assembly can be used in a conventional manner. Thus, the required number of MCBs 106 can be clipped onto the DIN bar and each finger of the bus bar is then inserted into a live terminal at the bottom of a respective MCB 106. When screwed tight, this gives a live feed (from the main switch) to all the MCBs, as in prior art installations. However, in this case a CT 104 is located between the bus bar 100 and each MCB 106, i.e. at the input, rather than the output, of each MCB. The CTs 104 are fitted at approximately the same location on each finger 102. A plastic (or other non conductive) housing 108 (see Figures 4 and 5) encases the CTs to prevent interference from the MCBs 106.

Each CT 104 is communicably coupled to a printed circuit board (PCB). At the interface between each of the CTs 104 and the PCB there is an analogue-to-digital converter (ADC) which converts the analogue signal of the alternating current into digital data. The present exemplary embodiment may use the 24bit Sigma Delta ADC. This gives a very accurate high resolution reading of the current, voltage and phase angle of the current drawn in the respective finger 102. Using this ADC, the current and voltage and be samples 1000 times per second per circuit (or finger 102).

The PCB is fitted with a modular connector 110 which is in turn connected to a cable. The modular connector 110 enables transmission of the digital signals from the ADCs to the control unit 200, via a respective single cable, 112. A further modular connector at the other end of the cable allows the data to be read by the control unit 200. Any suitable modular connector may be used.

The control unit 200 includes a power supply 202, a communications module 204 and a processing module 206. The power supply 202 provides power for the processing module 206. The power is drawn from the bus bar 100. A fuse 208 may be used to provide protection to the control unit 200 in the event of an electrical short. The power supply is also connected to an earthing point or neutral bar 210. The PCB is communicably coupled to the processing unit 206 (via the means of the modular connectors 110 and cable). Data representative of the current from each finger 102 is sent from the CTs 104 to the processing unit 206, whereupon algorithms calculate the voltage and phase angle of the current, and therefore provide an accurate reading of the power of each finger 102. This can be achieved in any known manner, and the present invention is not intended to be limited in this regard.

The communications module 204 may contain therein a wireless communications antenna, or an ethernet cable, as is known in the art, in order to transfer the data, now representative of the power being drawn at each finger 102, to a smart meter interface. Arrow A in Figure 3 generally indicates this transfer of data.

Referring now to Figure 4 of the drawings, a plan view of the above-described exemplary embodiment of the present invention is illustrated. It can be seen that the CTs 104 comprise a generally cube-shaped core 114 with a generally circular aperture 116. Each respective finger 102 acts as the primary conductor in the transformer having 1 ‘turn’, through which the alternating current (AC) flows creating a fluctuating magnetic field. This magnetic field is amplified by the core 114. As will be well understood by the person skilled in the art, the secondary conductor is formed by a wire (not shown) wrapped around the core, going up through the circular aperture 116 around the outer surface of the core 114 and back up through the circular aperture 116. This wire may be wrapped around the core 114 any number of times, though a common number in the art is 3000, giving 3000 ‘turns’ in the secondary conductor. The fluctuating magnetic field fluctuates through the secondary conductor, inducing an electromotive force (emf) within the ‘turns’. The magnetic field is proportional to the amperage of the AC in the primary conductor (the finger 102) and the emf produced within the wires is approximately 1/3,000 of the amperage of the primary current. Each of the CTs 104 is mounted to a printed circuit board (PCB) therefore removing the requirement for wires. The modular connector is also connected to the PCB.

Installation of the above-described bus bar is relatively easily achieved during installation of the power distribution board, but it can also be retrofitted if a new power distribution board is not requires, such that multi-channel smart metering capability can be provided. Compared with prior art assemblies and installation methods, the present invention had the effect of significantly reducing the cost of installing smart meter capability.

Referring now to Figure 5 of the drawings, an exemplary embodiment of the present invention is shown installed on a power distribution board 300. MCBs 106 are illustrated with output cables 302 leading to each respective circuit of the wiring system. The plastic covering 304 which normally covers the bus bar 100 is shown here as a dotted outline, to better illustrate the CTs 104. Each finger 102 has its own respective CT 104, even those without an MCB 106 fitted. This has the advantage that, once the bus bar 100 with the integrated CTs 104 is fitted, new circuit MCBs 106 can be added at any time without the need for re-testing the circuits, as would otherwise be required in prior art arrangements. The controller unit 200 can also be contained within the covering 304, such that the appearance of the power distribution board 300 is not altered by the presence of the CTs 104. However this is not essential.

The CTs 104 cannot be knocked or removed accidentally, therefore ensuring a more accurate and consistent data reading for the smart meter. Because all the CTs 104 are fitted to a PCB (not shown), there are no additional wires cluttering the cable area for the power distribution board, thus reducing the chances of accidental incorrect wiring due to unlabelled wires, for example. Additionally, the CTs are not affixed to the circuit cables 302 (seen best in Figure 5 of the drawings), therefore there is no need to interfere with these cables.

The whole system of the bus bar 100 and the control unit 200 is contained within the plastic covering 304 of the power distribution board 300. As such the overall appearance is not only greatly improved, but the system itself is simplified. In prior art devices the electronics for communications and processing would have to be housed elsewhere, whereas in exemplary embodiments of the invention, all components can be neatly contained in one place.

It will be appreciated by a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined in the appended claims.

Claims

1. A bus bar assembly for a power distribution board of an electrical wiring system, the assembly comprising a bus bar, having a conductive spine with a plurality of conductive elongate fingers extending, in parallel and spaced apart relation, from at least one edge thereof, each finger having a distal end configured to be inserted into a respective live input terminal of an MCB; wherein a current transformer is mounted over at least one of said fingers between its distal end and said spine and communicably coupled to a data collection unit including data transmission means configured to transmit data representative of a current transformer output to a control module

2. A bus bar assembly according to claim 1, wherein said data collection unit comprises a printed circuit board on which is provided an analogue to digital converter configured to sample current signals from said at least one current transformer.

3. A bus bar assembly according to claim 1 or claim 2, wherein said data transmission means comprises hard wired connection between said data collection unit and said control module.

4. A bus bar assembly according to any of the preceding claims, wherein each of a plurality of said fingers has a respective current transformer mounted thereon.

5. A bus bar assembly according to any of the preceding claims, wherein the or each said current transformer comprises a solid ferrite core, having primary and secondary conductors.

6. A bus bar assembly according to claim 5, wherein said primary conductor of the or each current transformer is the respective finger of said bus bar on which it is mounted, and wherein the secondary conductor of the or each current transformer comprises a wire, said wire being wrapped around said ferrite core a plurality of times.

7. A bus bar assembly according to any of the preceding claims, wherein said data collection unit comprises a printed circuit board incorporating an analogue to digital converter configured to sample current signals from said at least one current transformer, and wherein the two distal ends of said wire are mounted on, or otherwise electrically coupled to, said printed circuit board.

8. A bus bar assembly according to claim 3, wherein said data transmission means comprises a modular connector connected to said printed circuit board and connected by means of a communications cable to said control module so as to enable transmission of data representative of a current transformer output thereto.

5

9. A bus bar assembly according to any of the preceding claims, including said control module, wherein data representative of the current in the or each said finger is sent, via said connector, to said control module, said control module including a processing module configured to apply algorithms to said data, in order to obtain data representative of the power used at the or each said finger.

10 10. A bus bar assembly according to claim 9, wherein said control module includes a communications module comprising a wireless communications device, configured to communicate said power data wirelessly to a remote server or database to be stored.

11. A bus bar assembly according to any of the preceding claims, wherein said control module is connected to said bus bar and configured to be powered thereby.

15

12. A bus bar assembly according to any of the preceding claims, wherein the or each current transformer is a solid core current transformer having an aperture therethrough and being configured to be mounted on a respective finger of said bus bar by inserting said finger through said aperture.

13. A bus bar according to any of claims 1 to 11, wherein the or each said current 20 transformer is a split core current transformer configured to be clipped onto a respective finger of said bus bar.

14. A method of installing a power distribution board, comprising providing a DIN rail, connecting a main switch to a power supply and mounting said main switch to said DIN rail, mounting a plurality of MCBs at locations along said DIN rail, providing a

25 bus bar assembly according to any of the preceding claims, and inserting a distal end of each of a plurality of said fingers of said bus bar into the live input terminal of a respective MCB.

Intellectual

Property

Office

Application No: GB1701840.9 Examiner: Mr Tony Oldershaw