Electricity meter and method of testing and / or calibrating an electricity meter

Abstract

An electricity meter is disclosed. The electricity meter comprises at least one current sensing device configured to sense an electrical current at a first terminal of the meter. The electricity meter comprises at least one voltage sensing device. The electricity meter comprises an actuatable device coupled to the voltage sensing device and selectively configurable between a first state and a second state. In the first state the at least one voltage sensing device is configured to sense a first voltage between the first terminal and a second terminal of the meter. In the second state the at least one voltage sensing device is configured to sense a second voltage between the first terminal and a test point of the meter.

Description

[0001] ELECTRICITY METER AND METHOD OF TESTING AND / OR CALIBRATING AN ELECTRICITY METER

[0002] FIELD OF INVENTION

[0003] The present disclosure is in the field of electricity meters, and relates in particular to an electricity meter having an actuatable device for selectively coupling a voltage sensing device to a test point of the meter. The disclosure also relates to a method of testing and / or calibrating such an electricity meter.

[0004] BACKGROUND TO INVENTION

[0005] Electricity meters may comprise current and voltage sensing devices for metering consumption and / or production of electrical power at a premises and / or for monitoring one or more characteristics of a current and / or voltage supplied by the meter or consumed by a load coupled to the meter.

[0006] It is essential that such electricity meters are accurate and reliable. Typically, such electricity meters may undergo testing and / or calibration during manufacture and assembly, before shipping and installation at a premises.

[0007] It is known to implement electricity meters having manually removable links, also generally known in the art as “Test Links, “IP Links”, “Potential Links” or “Pot Links”.

[0008] By manually removing such test links from an electricity meter during a testing and / or calibration phase, it may be possible to supply a test current into a terminal of the electricity meter that is independent of an applied test voltage, e g. a voltage applied at a test point, i.e. a terminal of the test link.

[0009] That is, by removing the test link, current and voltage sensing circuits of the electricity meter may be isolated from one another. Removing the test link may disconnect a voltage powering the meter from the current coils.

[0010] For example, removal of the test link may allow a current circuit to be energized at a substantially lower voltage (e.g. <10V) than would be used in the field (e.g. 120V or 240V). As such, a single test panel may be capable of providing test voltages and currents to multiple electricity meters for purposes of test and / or calibration, without requiring a large power supply to the panel.

[0011] As such, removal of the test link enables test and calibration systems to apply voltages and currents independently to a unit under test. Such a test feature may, insome territories, be mandated. For example, said test link feature may be an American National Standards Institute (ANSI) requirement for some meter forms. This ‘test link’ feature is used mostly, if not exclusively, for test applications and not for field deployment.

[0012] However, implementation of one or more test links into an electricity meter may create design compromises to accommodate the test links, leading to a less than optimal design. For example, said test links must be readily accessible to allow for manual operation of the test links. This may be particularly problematic for high density electricity meter designs.

[0013] It is therefore desirable to provide an effective, low-cost, low complexity and highly reliable means for supporting testing and calibration of electricity meters, without having to comprise of a design of the meter due to inclusion of test links.

[0014] It is therefore an aim of at least one embodiment of at least one aspect of the present disclosure to obviate or at least mitigate at least one of the above identified shortcomings of the prior art.

[0015] SUMMARY OF INVENTION

[0016] The present disclosure is in the field of electricity meters, and in particular relates to an electricity meter having an actuatable device for selectively coupling a voltage sensing device to a test point of the meter. According to a first aspect of the disclosure, there is provided an electricity meter comprising:

[0017] at least one current sensing device configured to sense an electrical current at a first terminal of the meter;

[0018] at least one voltage sensing device; and

[0019] an actuatable device coupled to the voltage sensing device and selectively configurable between a first state and a second state, wherein:

[0020] in the first state the at least one voltage sensing device is configured to sense a first voltage between the first terminal and a second terminal of the meter; and

[0021] in the second state the at least one voltage sensing device is configured to sense a second voltage between the first terminal and a test point of the meter. Provision of an actuatable device may mitigate requirements to implement a test link that is capable of being manually removed or installed.That is, the actuatable device may provide means to disconnect a voltage powering the meter from the current sensing devices (e.g. current coils) for purposes of test and / or calibration, without having to comprise on a design of the electricity meter to accommodate a removable test link. This may be particularly beneficial for high density electricity meter designs, such as multi-port meters, or when new methods of interfacing metrology circuitry of the electricity meter to a baseplate assembly of the electricity meter are implemented. Provision of an actuatable device may mitigate a need for test links, which would otherwise result in additional wire assemblies and connections made during manufacturing.

[0022] While an actuatable device may be perceived as relatively more expensive than prior art solutions comprising manually removable test links, the prior art solutions are not as easily adaptable to types of base-plate assemblies currently in development for implementing modern multiport, high-density meters. As such, a total solution cost of the base plate assembly may be lower than that of a test-link capable base plate assembly.

[0023] The actuatable device may comprise a switchable device.

[0024] The actuatable device may comprise a relay.

[0025] The actuatable device may comprise a remotely actuatable device. Such an actuatable device may be configured to be remotely actuated.

[0026] The actuatable device may comprise an electromechanical or solid-state relay. In some examples, the actuatable device may be implemented as a sub-circuit, e.g. a sub-circuit that is capable of selectively interfacing to the test point.

[0027] The test point may comprise a conductive terminal, pin, probe-point, or the like, suitable for attachment or coupling of a conductive connector for applying a test voltage.

[0028] In the second configuration the at least one voltage sensing device may be isolated from the at least one current sensing device.

[0029] That is, the actuatable device may selectively isolate current and voltage sensing circuits of the electricity meter from one another.

[0030] The first state may be a default state of the actuatable device.

[0031] That is, the actuatable device may have a default configuration of coupling the current and voltage sensing circuits of the electricity meter, and thus a default state of the actuatable device is suitable for deployment in the field.

[0032] The actuatable device may comprise a relay.

[0033] Connections of the relay may be such that the relay is configured for a singlephase meter (e.g. a 1 PST) or a poly / multi-phase meter (e.g. 2PST, 3PST). Said relay may comprise a latching relay. In examples, the relay may be configured for a two-phaseor three phase meter. That is, in examples the electricity meter described herein may be a single phase, two phase or three phase meter. Thus, one or more actuatable devices may be provided for each phase of the meter.

[0034] The actuatable device may comprise at least one of: a single throw relay; a double throw relay; a latching relay; a sub-circuit.

[0035] In examples, double throw relays (1 PDT, 2PDT, 3PDT) may be used to emulate functionality switching a Voltage connection between the Current Coil and the test point with a common connection of the relay to the metrology circuit / power supply.

[0036] In the first state the actuatable device may connect the at least one voltage sensing device between the first terminal and the second terminal.

[0037] In the second state the actuatable device may connect the at least one voltage sensing device between the test point and the second terminal.

[0038] The test point may comprise a further terminal for coupling to an external voltage reference.

[0039] The at least one current sensing device may comprise at least one of: an alternating current transformer; a Hall-Effect sensor.

[0040] The current sensing device comprise a current transformer, also known in the art as a current coil, current transducer or ‘CT’.

[0041] The at least one voltage sensing device may comprise at least one of: a voltage transformer; a resistor divider network.

[0042] The voltage sensing device comprises a voltage transformer, also known in the art as a potential transformer, voltage or potential transducer, ‘PT’ or ‘VT.

[0043] The electricity meter may comprise a metrology circuit. The metrology circuit may be configured to receive a signal from the at least one current sensing device to determine at least one characteristic of the electrical current. The metrology circuit may be configured to receive a signal from the at least one voltage sensing device to determine at least one characteristic of the first and / or second voltage.

[0044] The term ‘metrology circuit’ will be understood to refer to a circuit configured for purposes of metering current and / or voltage, or determining, characterizing, monitoring and / or communicating and / or storing, logging and / or tracking one of more characteristics of current and / or voltage of an electrical power supply provided to or sourced from the meter. Such a metrology circuit may comprise a processor.

[0045] The metrology circuit may be configured to control the actuatable device.For example, the metrology circuit may be configured to actuate the actuatable device, such as in response to a trigger, a sensed condition, receipt of data or a message, or the like.

[0046] The electricity meter may comprise a base plate assembly comprising the first and second terminals, the at least one current sensing device and the at least one voltage sensing device.

[0047] The electricity meter may comprise multiple ports. For example, the electricity meter may be configured as a form 43S meter or the like, comprising a plurality of ports such as Distributed Energy Resource ports. As such, the electricity meter may be particularly densely populated compared to other more common electricity meter forms. Thus, to accommodate a large quantity of components, features of the electricity meter may be provided on a base plate assembly that is distinct from a printed circuit board comprising the metrology circuit.

[0048] The electricity meter may comprise a printed circuit board coupled to the base plate assembly and comprising the metrology circuit.

[0049] The printed circuit board may be stacked on the base plate assembly.

[0050] In some examples, the actuatable device may be provided on the base plate assembly. In some examples, the actuatable device may be provided on the printed circuit board.

[0051] The test point may be disposed on the base plate assembly and conductively coupled to the metrology circuit on the printed circuit board.

[0052] In one example, a test point I terminal may be implemented in the baseplate assembly with a lead attached to it. The lead may extend to a printed circuit board assembly, where the lead may interfaces with the actuatable device, e.g. a relay. In examples, said actuatable device may comprise a single pole Single throw Type B (normally closed ‘NC’) relay. A common of the relay may be connected to the metrology circuit and meter power supply (when applicable), while the NC contact may be connected to the current sensing device. Control of the actuatable device may then isolate the current sensing device from the voltage sensing device for the purpose of series testing.

[0053] The electricity meter may comprise a communications module. The actuatable device may be configured to transition between the first state and the second state in response to a signal received by the communications module.For example, control of the actuatable device may be by means of a command communicated to the meter through communications means, such as optical communication, Wi-Fi, Bluetooth, Radio / Cellular commands, or the like.

[0054] The electricity meter of may comprise a trigger circuit coupled to the test point. The actuatable device may be configured to transition between the first state and the second state in response to a signal received at the test point.

[0055] In some examples, control of the actuatable device may be provided directly from the test point termination, driving the coil / control directly or through some circuit.

[0056] The electricity meter may be, or may comprise, a multi-phase meter (e.g. a two-phase or a three phase meter) configured to meter an electric current and / or power and / or voltage of one or more phases of a multi phase electrical power supply.

[0057] The electricity meter may comprise a plurality of current sensing devices, each current sensing device configured to sense an electrical current of a respective different phase of the multi-phase electrical power supply.

[0058] The electricity meter may comprise a plurality of voltage sensing devices, each voltage sensing device associated with a respective different phase of the multi-phase electrical power supply.

[0059] The electricity meter may comprise at least one actuatable device coupled to at least one of the plurality of voltage sensing devices, each at least one actuatable device selectively configurable between a first state and a second state, wherein: in the first state each at least one voltage sensing device is configured to sense a voltage of the respective phase of the multi-phase electrical power supply, and in the second state each at least one voltage sensing device is configured to sense a voltage at the test point or at a further test point of the meter.

[0060] According to a second aspect of the disclosure, there is provided a method of testing and / or calibrating an electricity meter, the method comprising:

[0061] providing a meter according to the first aspect;

[0062] coupling a source of electrical power to the electricity meter, wherein a first source provides a test or calibration voltage to the test pin and a second source provides a test or calibration current to the first terminal; and

[0063] configuring the actuatable device into the second state.

[0064] The above summary is intended to be merely exemplary and non-limiting. The disclosure includes one or more corresponding aspects, embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. It should be understood that features defined abovein accordance with any aspect of the present disclosure or below relating to any specific embodiment of the disclosure may be utilized, either alone or in combination with any other defined feature, in any other aspect or embodiment or to form a further aspect or embodiment of the disclosure.

[0065] BRIEF DESCRIPTION OF DRAWINGS

[0066] These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, wherein:

[0067] Figure 1 depicts a block diagram of an example electricity meter, according to an embodiment of the disclosure;

[0068] Figure 2 depicts a circuit for an electricity meter wherein the actuatable device is implemented as a Form C relay, according to an embodiment of the disclosure;

[0069] Figure 3 depicts a circuit for an electricity meter wherein the actuatable device is implemented as a Form A relay, according to an embodiment of the disclosure;

[0070] Figure 4 depicts a diagram of a Form 2S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0071] Figures depicts a diagram of a Form 12S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0072] Figures depicts a diagram of a Form 14S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0073] Figure? depicts a diagram of a Form 15S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0074] Figures depicts a diagram of a Form 17S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0075] Figure 9 depicts a diagram of a Form 32S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;Figure 10 depicts a diagram of a Form 43S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure;

[0076] Figure 11 depicts a diagram of a Form 112S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure; and

[0077] Figure 12 depicts a diagram of a Form 116S electricity meter, wherein mechanical links are replaced with actuatable devices, according to an embodiment of the disclosure.

[0078] DETAILED DESCRIPTION OF DRAWINGS

[0079] Figure 1 depicts a block diagram of an example electricity meter 100, according to an embodiment of the disclosure. It will be understood that only features of the electricity meter 100 required to describe the disclosed invention are depicted, and that the electricity meter 100 may comprise other features and components that are not depicted.

[0080] The electricity meter 100 comprises a current coil 105. Also depicted is a further current coil 110. Although only two current coils 105, 110 are depicted, it will be understood that this is for purposes of illustration, and other electricity meter configurations may comprises more than two current coils.

[0081] In use, one or both of the current coils 105, 110 may be connected in series with a load circuit to provide an indication of a current drawn by the load. That is, one of both of the current coils 105, 110 may be configured for use as a current sensing device.

[0082] In use, one or both of the current coils 105, 110 may be connected across supply lines, e.g. between terminals of the meter, such between a first phase line and a second phase line, to provide a current proportional to a supply voltage for purposes of voltage sensing. That is, one of both of the current coils 105, 110 may be effectively configured as a voltage sensing device.

[0083] Also depicted in an actuatable device 115. In this example, the actuatable device comprises a relay. Specifically, the actuatable device 115 in the example of Figure 1 comprises a single pole, double throw (SPDT or ‘1 PDT’) relay.

[0084] The actuatable device 115 of Figure 1 may be implemented as an electromechanical or solid-state relay. In some examples (not depicted), the actuatable device 115 may instead be implemented as a sub-circuit.Also depicted in Figure 1 is a circuit 120, hereafter referred to as a metrology circuit 120. The metrology circuit 120 may be configured for purposes of metering current and / or voltage, or determining, characterizing, monitoring and / or communicating, storing, logging and / or tracking one of more characteristics of current and / or voltage of an electrical power supply to or from the meter 100.

[0085] In the example, the current coil 105 and further current coil 110 are disposed on a base plate assembly 125, denoted ‘BPA’. The base plate assembly 125 may, for example, comprises a supporting substrate which the current coil 105 and further current coil 110 are coupled to.

[0086] In the example, the metrology circuit 120 is disposed on a printed circuit board, and thus is collectively denoted “metrology PCB” in Figure 1.

[0087] The actuatable device 115 (relay) has a common terminal 130 coupled to the metrology circuit 120.

[0088] The metrology circuit 120 may be configured to control the actuatable device 115. In the depicted example, the metrology circuit 120 may be configured to control a coil 140 of the actuatable device 115, to control actuation of the actuatable device 115, e.g. switching of the relay.

[0089] In some examples, a first terminal 145 of the actuatable device 115 is coupled to the current coil 105. A second terminal 150 of the actuatable device 115 is coupled to a test point 135. The test point 135 may comprise a conductive terminal, pin, probe-point, or the like, suitable for attachment of a conductive connector for applying a test voltage. In an example, the current coil 105 may be configured as a voltage sensing device, e.g. by providing a current proportional to a size of a voltage across the current coil 105. As such, the depicted actuatable device 115 is shown as effectively coupled to a voltage sensing device and selectively configurable between a first state and a second state, wherein: in the first state the current coil 105 (e.g. the voltage sensing device) is configured to sense a first voltage between a first terminal (not shown) and a second terminal (not shown) of the meter, and in a second state the current coil 105 may be configured for sensing a second voltage between the first terminal and the test point 135 of the meter 100.

[0090] In some examples, the meter 100 may comprise a communications module 165. The actuatable device 115 may be configured to transition between the first state and the second state in response to a signal received by the communications module 165.For example, control of the actuatable device 115 may be by means of a command communicated to the meter through the communications module 165, such as optical communication, Wi-Fi, Bluetooth, Radio / Cellular commands, or the like.

[0091] Specific operation of examples of the disclosed invention is now described with reference to Figures 2 and 3.

[0092] It will be understood that the inventive concepts described herein may be applicable to single phase and / or multi-phase meters, such as two-phase or three-phase meters. That is, in examples of the disclosure, a two-phase or three-phase electricity meter may comprise: at least one current sensing device configured to sense an electrical current at a first terminal of the meter; at least one voltage sensing device; and an actuatable device coupled to the voltage sensing device and selectively configurable between a first state and a second state, wherein: in the first state the at least one voltage sensing device is configured to sense a first voltage between the first terminal and a second terminal of the meter; and in the second state the at least one voltage sensing device is configured to sense a second voltage between the first terminal and a test point of the meter.

[0093] Such meters may, for example, comprise a plurality of current sensing device, each current sensing device configured to sense an electrical current at a respective terminal of the meter.

[0094] Similarly, in examples such meters may additionally or alternatively comprise a plurality of voltage sensing devices.

[0095] Such examples may comprise a plurality of actuatable devices.

[0096] Such examples may comprise a plurality of test points.

[0097] For example, each actuatable device may be coupled to a respective voltage sensing device of the plurality of voltage sensing devices, and individually or collectively selectively configurable between a first state and a second state, wherein: in the first state the respective voltage sensing device is configured to sense a voltage between terminals of the meter; and in the second state the respective voltage sensing device is configured to sense a voltage between one of said terminals and a respective test point of the meter. In such examples, each actuatable device may be associated with a particular phase. For example, said electricity meter may comprise: a first actuatable device configurable to enable sensing of a voltage between one of said terminals associated with a first phase and a respective test point of the meter; a second actuatable device configurable to enable sensing of a voltage between one of said terminals associated with a second phase and a / the respective test point of the meter; and / or athird actuatable device configurable to enable sensing of a voltage between one of said terminals associated with a third phase and a / the respective test point of the meter.

[0098] Figure 2 depicts a diagram of a circuit 200 for an electricity meter, wherein an actuatable device is implemented as a Form C relay, according to an example of the disclosure.

[0099] The circuit includes a first terminal 205 and a second terminal 210 of the meter. A first current coil 215 is proved in series between the first terminal 205 and the second terminal 210 for sensing a current flowing at the first terminal 205.

[0100] The circuit includes a third terminal 220 and a fourth terminal 225 of the meter. A second current coil 230 is proved in series between the third terminal 220 and the fourth terminal 225 for sensing a current flowing at the third terminal 220.

[0101] The circuit includes a voltage transformer 235. A first terminal of the voltage transformer 235 is coupled to the first terminal 205 of the meter. A second terminal of the voltage transformer 235 is coupled to an actuatable device, which in the disclosed example is a Single Pole Double Throw relay (SPDT) 240. The second terminal of the voltage transformer 235 is coupled to a common terminal 250 of the SPDT relay 240.

[0102] Figure 2 depicts the SPDT relay 240 in a default state. That is, in the example, the SPDT relay 240 is a ‘Form C’ relay, and therefore has a ‘Normally Open’ default state, wherein the common terminal 250 is coupled to the first terminal 255 of the SPDT relay 240.

[0103] In an actuated state, the SPDT relay 240 is configured such that common terminal 250 is coupled to a test point 275 of the meter (via a second terminal 280 of the SPDT relay). Said test point 275 may comprise a conductive terminal, pin, probe-point, or the like, suitable for attachment of a conductive connector for applying a test voltage.

[0104] Furthermore, it can be seen that when the SPDT relay 240 is in an actuated state (i.e. common terminal 250 coupled to second terminal 280), the voltage transformer 235 is electrically isolated from the second current coil 230.

[0105] For completeness, a source 260 providing electrical power to the circuit 200 is also depicted, where the source is by default connected between the first terminal 205 and the third terminal 220.

[0106] Although not depicted, in use a load may be provided between the second terminal 210 and the fourth terminal 225.

[0107] In an example use of the meter, a line voltage may be applied across the first terminal 205 and the third terminal 220 of the meter, inducing a flow of current from the source 260 to the load (not depicted).A metrology circuit may be configured to control the SPDT relay 240 and configured to receive signals from each of the first current coil 215, the second current coil 230 and the voltage transformer 235. For simplicity of illustration the metrology circuit is not depicted, but may be generally correspond to, or be equivalent to the metrology circuit 120 of Figure 1 . As described above, such a metrology circuit may, for example, comprise a processor and may be configured for metering current and / or voltage, or determining, characterizing, monitoring and / or communicating and / or storing, logging and / or tracking one of more characteristics of current and / or voltage of an electrical power supply to or from the meter.

[0108] Thus, the circuit 200 of Figure 2 comprises:

[0109] at least one current sensing device, e.g. first current coil 215, configured to sense an electrical current at a first terminal 205 of the meter;

[0110] at least one voltage sensing device, e.g. voltage transformer 235; and an actuatable device, e.g. SPDT relay 240, coupled to the voltage sensing device and selectively configurable between a first state and a second state, wherein:

[0111] in the first state, e.g. the default state, the at least one voltage sensing device, e.g. voltage transformer 235, is configured to sense a first voltage between the first terminal 205 and a further terminal, e.g. third terminal 220, of the meter; and

[0112] in the second state the at least one voltage sensing device, e.g. voltage transformer 235, is configured to sense a second voltage between the first terminal 205 and a test point 275 of the meter.

[0113] In other examples, a default state of the SPDT relay 240 may connect the common terminal 250 to the second terminal 280 of the SPDT relay 240.

[0114] Figure 3 depicts a diagram of a circuit 300 for an electricity meter, wherein an actuatable device is implemented as a Form A relay, according to an example of the disclosure.

[0115] The circuit includes a first terminal 305 and a second terminal 310 of the meter. A first current coil 315 is proved in series between the first terminal 305 and the second terminal 310 for sensing a current flowing at the first terminal 305.

[0116] The circuit includes a third terminal 320 and a fourth terminal 325 of the meter. A second current coil 330 is proved in series between the third terminal 320 and the fourth terminal 325 for sensing a current flowing at the third terminal 320.The circuit includes a voltage transformer 335. A first terminal of the voltage transformer 335 is coupled to the first terminal 305 of the meter. A second terminal of the voltage transformer 335 is coupled to an actuatable device, which in the disclosed example is a Single Pole Single Throw relay (SPST) 240. The second terminal of the voltage transformer 335 is coupled to a first terminal 350 of the SPST relay 340.

[0117] Figure 3 depicts the SPST relay 340 in an actuated state. That is, in the example, the SPST relay 340 is a ‘Form A’ relay, and therefore when actuated the first terminal 350 of the SPST relay 340 is coupled to a second terminal 355 of the SPST relay 240.

[0118] The first terminal 350 of the SPST relay 340 is also coupled to a test point 375. Said test point 375 may comprise a conductive terminal, pin, probe-point, or the like, suitable for attachment of a conductive connector for applying a test voltage.

[0119] Furthermore, it can be seen that when the SPST relay 340 is not in the actuated state, the voltage transformer 335 is electrically isolated from the second current coil 330.

[0120] For completeness, a source 360 providing electrical power to the circuit 300 is also depicted, where the source is connected between the first terminal 305 and the third terminal 320 when the SPST relay 340 in an actuated state.

[0121] Although not depicted, in use a load may be provided between the second terminal 210 and the fourth terminal 325.

[0122] In an example use of the meter, a line voltage may be applied across the first terminal 305 and the third terminal 320 of the meter, inducing a flow of current from the source 260 to the load (not depicted).

[0123] A metrology circuit may be configured to control the SPST relay 340 and configured to received signals from each of the first current coil 315, the second current coil 330 and the voltage transformer 335. For simplicity of illustration, the metrology circuit is not depicted. As described above, such a metrology circuit may, for example, comprise a processor and may be configured for metering current and / or voltage, or determining, characterizing, monitoring and / or communicating and / or storing, logging and / or tracking one of more characteristics of current and / or voltage of an electrical power supply to or from the meter.

[0124] Thus, the circuit 300 of Figure 3 comprises:

[0125] at least one current sensing device, e.g. first current coil 315, configured to sense an electrical current at a first terminal 305 of the meter;

[0126] at least one voltage sensing device, e.g. voltage transformer 335; andan actuatable device, e.g. SPST relay 340, coupled to the voltage sensing device and selectively configurable between a first state and a second state, wherein:

[0127] in the first state, the at least one voltage sensing device, e.g. voltage transformer 335, is configured to sense a first voltage between the first terminal 305 and a further terminal, e.g. third terminal 320, of the meter; and

[0128] in the second state e.g. the default state, the at least one voltage sensing device, e.g. voltage transformer 335, is configured to sense a second voltage between the first terminal 305 and a test point 375 of the meter.

[0129] In other examples, a default state of the SPST relay 340 may be a closed state, e.g. connecting the first terminal 350 and the second terminal 355 of the SPST relay 340.

[0130] In a method of testing and / or calibrating any of the above-described meters, the actuatable device 240, 340 may be configured to effectively isolate the voltage transformer 235, 335 from a current coil 230, 330, thereby enabling a test and calibration systems (also known as a test or calibration panel) to apply voltages and currents independently to a meter under test.

[0131] Figures 2 and 3 depict examples of meter forms having two ports with two current coils and voltage transformer. It will be appreciated that the inventions disclosed herein is applicable to other meter forms with other amounts and configurations of ports and / or current coils and / or voltage transformers and / or actuatable devices.

[0132] Furthermore, Figures 2 and 3 depict examples of meter forms implementing Form C and Form A relays respectively. It will be appreciated by one of skill in the art that implementations implementing one or more Form B relays also fall within the scope of the disclosure.

[0133] For example, Figure 4 depicts a Form 2S meter configuration (as defined by ANSI standards), suitable for a single phase supply. The switch 405 (which may typically represent a manually removable link) may be considered to represent an actuatable device, e.g. a relay, as described above with reference to Figures 1 to 3. In other examples:

[0134] Figure 5 depicts a Form 12S meter wherein switches 505, 510 may be implemented as actuatable devices in accordance with the disclosed invention; Figure 6 depicts a Form 14S meter wherein switches 605, 610 may be implemented as actuatable devices in accordance with the disclosed invention; Figure 7 depicts a Form 15S meter wherein switches 705, 710 may be implemented as actuatable devices in accordance with the disclosed invention;- Figure 8 depicts a Form 17S meter wherein switches 805, 810, 815 may be implemented as actuatable devices in accordance with the disclosed invention; - Figure 9 depicts a Form 32S meter wherein switch 905 may be implemented as an actuatable device in accordance with the disclosed invention;

[0135] Figure 10 depicts a Form 43S meter wherein switches 1005, 1010 may be implemented as actuatable devices in accordance with the disclosed invention; Figure 11 depicts a Form 112S meter wherein switch 1110 may be implemented as an actuatable device in accordance with the disclosed invention; and Figure 12 depicts a Form 116S meter wherein switch 1205 may be implemented as an actuatable device in accordance with the disclosed invention.

[0136] It will be appreciated that this list is non-exhaustive, and other meter forms may also be adapted with actuatable devices in accordance with the disclosed invention.

[0137] Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure, which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in any embodiments, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.REFERENCE NUMERALS

[0138] 100 meter 300 circuit

[0139] 105 current coil 305 first terminal

[0140] 110 current coil 310 second terminal 115 actuatable device 315 first current coil 120 metrology circuit 35 320 third terminal

[0141] 125 base plate assembly 325 fourth terminal 130 common terminal 330 second current coil 135 test point 335 voltage transformer 140 coil 340 SPST relay

[0142] 145 first terminal 40 350 first terminal (of SPST 150 second terminal relay)

[0143] 165 communications module 355 second terminal (of 200 circuit SPDT relay)

[0144] 205 first terminal 360 source

[0145] 210 second terminal 45 375 test point

[0146] 215 first current coil 405 Switch

[0147] 220 third terminal 505, 510 Switches

[0148] 225 fourth terminal 605, 610 Switches

[0149] 230 second current coil 705, 710 Switches

[0150] 235 voltage transformer 50 805, 810 Switches

[0151] 240 SPDT relay 815 Switch

[0152] 250 common terminal 905 Switch

[0153] 255 first terminal (of SPDT 1005, 1010 Switches

[0154] relay) 1105 Switch 260 source 55 1205 Switch

[0155] 275 test point 1305, 1310, 1315 Switches 280 second terminal (of 1405, 1410, 1415, 1420 Switches SPDT relay)

Claims

CLAIMS1 . An electricity meter comprising:at least one current sensing device configured to sense an electrical current at a first terminal of the meter;at least one voltage sensing device; andan actuatable device coupled to the voltage sensing device and selectively configurable between a first state and a second state, wherein:in the first state the at least one voltage sensing device is configured to sense a first voltage between the first terminal and a second terminal of the meter; andin the second state the at least one voltage sensing device is configured to sense a second voltage between the first terminal and a test point of the meter.

2. The electricity meter of claim 1 , wherein the actuatable device comprises a relay.

3. The electricity meter of claim 1 or 2, wherein the actuatable device comprises at least one of:a single throw relay;a double throw relay;a latching relay;a sub-circuit4. The electricity meter of any preceding claim, wherein in the second configuration the at least one voltage sensing device is isolated from the at least one current sensing device.

5. The electricity meter of any preceding claim, wherein the first state is a default state of the actuatable device.

6. The electricity meter of any preceding claim wherein:in the first state the actuatable device connects the at least one voltage sensing device between the first terminal and the second terminal; andin the second state the actuatable device connects the at least one voltage sensing device between the test point and the second terminal.

7. The electricity meter of any preceding claim, wherein at least one of:the test point comprises a further terminal for coupling to an external voltage reference;the at least one current sensing device comprises at least one of: a current coil, an alternating current transformer; a Hall-Effect sensor; and / or the at least one voltage sensing device comprises at least one of: a current coil, a voltage transformer; a resistor divider network.

8. The electricity meter of any preceding claim, comprising a metrology circuit configured to:receive a signal from the at least one current sensing device to determine at least one characteristic of the electrical current; and / orreceive a signal from the at least one voltage sensing device to determine at least one characteristic of the first and / or second voltage.

9. The electricity meter of claim 8 wherein the metrology circuit is configured to control the actuatable device.

10. The electricity meter of any preceding claim, comprising a base plate assembly comprising the first and second terminals, the at least one current sensing device and the at least one voltage sensing device.11 . The electricity meter of claim 8, when dependent upon claim 6, comprising a printed circuit board coupled to the base plate assembly and comprising the metrology circuit.

12. The electricity meter of claim 11 , wherein the test point is disposed on the base plate assembly and conductively coupled to the metrology circuit on the printed circuit board.

13. The electricity meter of any preceding claim, comprising a communications module, and wherein the actuatable device is configured to transition betweenthe first state and the second state in response to a signal received by the communications module.

14. The electricity meter of any preceding claim, comprising a trigger circuit coupled to the test point, and wherein the actuatable device is configured to transition between the first state and the second state in response to a signal received at the test point.

15. The electricity meter of any preceding claim, wherein the meter is a multi-phase meter configured to meter an electric current and / or power and / or voltage of one or more phases of a multi-phase electrical power supply.

16. The electricity meter of any preceding claim, comprising:a plurality of current sensing devices, each current sensing device configured to sense an electrical current of a respective different phase of the multi-phase electrical power supply;a plurality of voltage sensing devices, each voltage sensing device associated with a respective different phase of the multi-phase electrical power supply;at least one actuatable device coupled to at least one of the plurality of voltage sensing devices, each at least one actuatable device selectively configurable between a first state and a second state, wherein:in the first state each at least one voltage sensing device is configured to sense a voltage of the respective phase of the multi-phase electrical power supply, andin the second state each at least one voltage sensing device is configured to sense a voltage at the test point or at a further test point of the meter.

17. A method of testing and / or calibrating an electricity meter, the method comprising:providing a meter according to any preceding claim;coupling a source of electrical power to the electricity meter, wherein a first source provides a test or calibration voltage to the test pin and a second source provides a test or calibration current to the first terminal;configuring the actuatable device into the second state.

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