Patent Description:
The present disclosure relates generally to utility meters. Specifically, the present disclosure relates to systems and methods of sensing load-side voltages within a metrology device such as an electrical power meter.

Utility metering units or devices such as electric, water, and gas meters are devices that measure the amount of the utility such as electricity, water, and gas consumed by a residence, a commercial property, or an electrically powered device. As consumers of the utility consume the utility, the consumer is expected to compensate the entity providing the utility (e.g., utility company). Oftentimes, the consumer is either unable or unwilling to provide such compensation, and the utility company may restrict the consumer's access to the utility by physically disconnecting the utility from the consumer's building or engaging a disconnect device that restricts consumption of the utility.

For example, electrical power measured by a utility metering unit such as an electrical power meter, may be remotely disconnected by an administrator operating at a central office located remote with respect to the consumer's building. This remote disconnection of the electrical power may be performed by remotely instructing the electrical power meter to stop providing the electrical power via a power line communication (PLC) system with a disconnect signal being communicatively propagated through a network of electrical power meters communicated using a PLC communications technology. The disconnect signal may cause a disconnect switch to open causing electricity to cease to flow through the electrical power meter into the consumer's building.

In instances where electrical power is disconnected from the consumer's building, the consumer may attempt to obtain electrical power from an alternative electrical power source including, for example, from a generator connected to the consumer's building, an alternative power source such as a photovoltaic cell array, by running electrical cable from a neighboring building and utilizing the electrical power supplied to the neighboring building, or by some other means of obtaining electrical power apart from the electrical power utility provider. The consumer may also attempt to bypass the electrical power meter altogether. In these instances, and before the utility is restored to the consumer's building, a voltage is created on the load-side of the electrical power meter via the alternative electrical power source.

In instances where the consumer properly compensates the utility company for the consumed utility (e.g., electrical power), the consumed utility may be restored to the consumer's building once again for consumption. In past utility restoration processes, a technician may physically visit the consumer's building and restore access to the utility. During the visit by the technician, the technician may be able to determine whether the alternative source of electrical power is still connected to the consumer's building, and may disconnect the alternative source of electrical power to avoid damage to the electrical power meter, the devices and/or circuits associated with the alternative source of electrical power, the consumer's building, and other property.

However, because the utility company can restore the electrical power to the consumer's building remotely via an administrator operating at the central office and the PLC system, the utility company may not be aware of the alternative electrical power source coupled to the load-side of the electrical power meter without a physical inspection by the technician. Reconnecting the electrical power to the consumer's building via instruction to the electrical power meter via the PLC system may cause a number of issues. For example, a technician that may be otherwise dispatched to reconnect the electrical power, is not dispatched because the reconnection is performed remotely. Thus, no inspection of the consumer's building is made including a determination as to whether the alternative electrical power source is coupled to the load-side of the electrical power meter and/or whether a voltage is present on the load-side of the electrical power meter which indicates that the alternative electrical power source is present.

Not performing such an inspection to detect load-side voltages may result in serious damage to, for example, devices and/or circuit elements electrically coupled to the load-side of the electrical power meter should the disconnect switch of the electrical power meter be closed. For example, damage to a generator or other power circuit(s) included within, for example, the neighboring building that are coupled to the load-side of the electrical power meter may occur including shorting out of the power circuit(s). Further, reconnection of the electrical power to the electrical power meter without performing load-side detection in the presence of a load-side voltage may result in damage to the electrical power meter including catastrophic damage to electrical components therein. Still further, such oversight in load-side detection in the presence of a load-side voltage may result in other types of serious electricity-related incidents and accidents including electricity-related fires.

<CIT> describes an arrangement for use in a utility meter including at least one circuit path, a three phase service switch, and a three phase monitoring unit. The at least one circuit path operably couples a source of electrical energy to a load. The service switch is operably coupled to the at least one circuit path and is configurable in an open state and a closed state. The monitoring unit is operably coupled to the at least one circuit path between the load and the service switch and is configured to detect a presence and an absence of line voltage on the load. The monitoring unit is further configured (i) to generate an open circuit signal responsive to the detection of the absence of line voltage on the load, and (ii) to generate a closed circuit signal responsive to the detection of the presence of line voltage on the load.

As mentioned above, a utility metering unit (also referred to herein as a "utility meter" or a "metrology device") may be instructed by a remote central office to remotely open and close a disconnect switch of the utility metering unit (e.g., electrical power meter) to disconnect and connect/reconnect the utility service (e.g., electrical power) provided via the utility metering unit. However, the presence of a load-side voltage at the utility metering unit may protect the utility metering unit, devices and/or circuits associated with an alternative source of electrical power coupled to the load-side of the utility metering unit, the consumer's building, and other property from being damaged.

In some areas of the world, government or industry testing requirements may include functionality for detecting load-side voltage with a solid-state meter in order to avoid the potential of damage in instances where the alternative source of electrical power is coupled to the load-side of the utility metering unit as described herein. For example, the National Electrical Manufacturers Association (NEMA) has released standard C12. <NUM> in <NUM> entitled, "Test Requirements for Metering Devices Equipped with Service Switches" (hereinafter "NEMA C12. <NUM> includes requirements that previously established methods may not meet. For example, NEMA C12. <NUM> includes requirements for an electric meter to be able to detect the presence of a back-feed voltage on the load-side terminals and prevent closure of the disconnect switch in the event that back feed voltage above a certain level or threshold is detected. These requirements specify back feed voltage thresholds that are to be used to determine when to close or refrain from closing the disconnect switch of the utility metering unit. These thresholds may be different depending on whether the voltage detected on the load-side terminals of the meter are in-phase or out-of-phase with each other.

In the examples described herein, a load-side voltage detection module for a metrology device according to claim <NUM> may be used to identify instances where the disconnect switch of the metrology device may be closed safely without risk of the damage to the utility metering unit, devices and/or circuits associated with an alternative source of electrical power coupled to the load-side of the utility metering unit, the consumer's building, and other property described herein. Further, the examples described herein provide systems and methods to remotely disconnect and connect/reconnect the utility service (e.g., electrical power) provided via the utility metering unit without the need to dispatch a technician to the utility metering unit while maintaining the safety measures afforded by the load-side detection module.

Examples described herein provide a load-side voltage detection module for a metrology device. The load-side voltage detection module may include a plurality of first resistors electrically coupled to a first load-side terminal, the first resistors being in series, and a plurality of second resistors electrically coupled to a second load-side terminal, the second resistors being in series. The load-side voltage detection module may also include a voltage divider electrically coupled between a first line-side terminal and a second line-side terminal, the voltage divider creating a reference voltage (e.g., a virtual ground voltage) for the load-side voltage detection module. The load-side voltage detection module may also include a pulse generator to generate a pulse based on detection of voltage, the pulse indicating a voltage on the first load-side terminal and/or the second load-side terminal above at least one threshold.

The first load-side terminal and the second load-side terminal are in phase or out of phase with respect to one another. The first resistors and the second resistors have different resistance values. In one example, the pulse generator may include a first diode, a second diode in series with the first diode, a capacitor in parallel with the first diode, a first transistor, a second transistor in series with the first transistor, the first transistor and the second transistor being in parallel with the capacitor, and an optoisolator electrically coupled to the second transistor, the optoisolator generating the pulse on an isolated output. The pulse may be output to an application specific integrated circuit (ASIC) of the metrology device. The voltage divider creates a virtual ground.

In one example, the pulse generator may include a first transistor electrically coupled to the first resistors, and a second transistor electrically coupled to the second resistors, the first transistor and the second transistor generating the pulse on an isolated output.

Examples described herein also provide a metrology device including a load-side voltage detection module. The load-side voltage detection module includes a plurality of first resistors electrically coupled to a first load-side terminal, the first resistors being in series, a plurality of second resistors electrically coupled to a second load-side terminal, the second resistors being in series, a voltage divider electrically coupled between a first line-side terminal and a second line-side terminal, the voltage divider creating a reference voltage for the load-side voltage detection module, and a pulse generator to generate a pulse based on detection of voltage, the pulse indicating a voltage on at least one of the first load-side terminal or the second load-side terminal above at least one threshold.

The pulse generator includes a first diode, a second diode in series with the first diode, a capacitor in parallel with the first diode, a first transistor, a second transistor in series with the first transistor, the first transistor and the second transistor being in parallel with the capacitor, and an optoisolator electrically coupled to the second transistor, the optoisolator generating the pulse on an isolated output. The pulse generator includes a first transistor electrically coupled to the first resistors, and a second transistor electrically coupled to the second resistors, the first transistor and the second transistor generating the pulse on an isolated output.

The first load-side terminal voltage and the second load-side terminal voltage may be out of phase with respect to one another. The first resistors and the second resistors have different resistance values. The pulse may output to an application specific integrated circuit (ASIC) of the metrology device. The voltage divider may be used to create a reference voltage (e.g., a virtual ground voltage). The metrology device may further include a load-side voltage disconnect switch electrically coupled to the load-side voltage detection module.

Examples described herein also provide a network that includes a metrology device communicatively coupled within the network, and a central office communicatively coupled to the metrology device at least in part over a power line. The metrology device includes a metrology unit. The metrology unit includes a load-side voltage detection circuit. The load-side voltage detection module includes a plurality of first resistors electrically coupled to a first load-side terminal, the first resistors being in series, a plurality of second resistors electrically coupled to a second load-side terminal, the second resistors being in series, a voltage divider electrically coupled between a first line-side terminal and a second line-side terminal, the voltage divider creating a reference voltage (e.g., a virtual ground voltage) for the load-side voltage detection module, and a pulse generator to generate a pulse based on detection of voltage, the pulse indicating a voltage on at least one of the first load-side terminal or the second load-side terminal above at least one threshold.

The pulse generator may include a first diode, a second diode in series with the first diode, a capacitor in parallel with the first diode, a first transistor, a second transistor in series with the first transistor, the first transistor and the second transistor being in parallel with the capacitor, and an optoisolator electrically coupled to the second transistor, the optoisolator generating the pulse on an isolated output.

The pulse generator may include a first transistor electrically coupled to the first resistors, and a second transistor electrically coupled to the second resistors, the first transistor and the second transistor generating the pulse on an isolated output.

The first resistors and the second resistors have different resistance values, and the voltage divider may be a virtual voltage divider. The network may further include a load-side voltage disconnect switch electrically coupled to the load-side voltage detection module.

Additionally, the techniques described in this disclosure may be performed as a method and/or by a system having non-transitory computer-readable media storing computer-executable instructions that, when executed by one or more processors, performs the techniques described above.

Turning now to the figures, <FIG> is a diagram showing a high-level view of a network architecture <NUM> including nodes <NUM> configured with a load-side voltage detection module. <FIG> also includes a component diagram of example components of a node <NUM> that includes a load-side voltage detection (LVD) module <NUM>. The network architecture <NUM> includes a plurality of node(s) <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-N, where N is any integer greater than or equal to <NUM> (collectively referred to herein as node(s) <NUM> unless specifically addressed otherwise). The nodes <NUM> are communicatively coupled to each other via direct communication paths or "links. " In this example, N represents a number of nodes in an autonomous routing area (ARA), such as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), neighborhood area network (NAN), field area network (FAN), personal area network (PAN), among other types of networks. As an example, nodes <NUM> may be configured in a radio frequency (RF) mesh, a power line communication (PLC) mesh, or both. In one example, nodes <NUM> may be part of a low power and lossy network (LLN).

As used in the present specification and in the appended claims, the term "link" is meant to be understood broadly as any direct communication path between two nodes (e.g., a "one hop" transmission that does not pass through or become propagated by another node). Each link may represent a plurality of channels or one or more variable data rate channels over which a node <NUM> is able to transmit or receive data. Each link may include multiple communication technologies, such as, for example, one or more RF communication technologies, one or more PLC communication technologies, or both (among other communication technologies). Thus, the communication technologies may utilize RF signals and/or PLC signals (among other types of signals) in communicating with one another and with other devices, systems, and networks such as, for example, a central office <NUM>.

One or more channels may use a power line communication (PLC) system to communicate using a PLC communications technology. Thus, a link may include portions based on multiple communication medias including PLC portions. Likewise, various links may use multiple different PLC communications technologies (e.g., various modulation techniques, bandwidths, data rates, center frequencies, protocols, etc.).

The channels on a link may include a control channel and multiple data channels. In one example, the control channel may be utilized for communicating one or more messages between nodes to specify one of the data channels utilized to transfer data. Transmissions on the control channel may be shorter relative to transmissions on the data channels. Once specified, the nodes <NUM> may move to the data channel for communication.

Each of the nodes <NUM> may be implemented as, or associated with, any of a variety of computing devices such as, for example, smart utility meters (e.g., electric, gas, and/or water meters), sensors (e.g., temperature sensors, weather stations, frequency sensors, etc.), control devices, transformers, routers, servers, relays (e.g., cellular relays), switches, valves, power line communication (PLC) transceivers, combinations of the foregoing, or any device couplable to a communication network and capable of sending and/or receiving data.

In this example, the nodes <NUM> may also be configured to communicate with one or more central processing facilities such as the central office <NUM> via an edge device (e.g., cellular relay, cellular router, edge router, destination oriented directed acyclic graph (DODAG) root, etc.) which serves as a connection point of the ARA to a backhaul network(s), such as the Internet or one or more public or private intranets. In the illustrated example, node <NUM>-<NUM> and/or <NUM>-<NUM> may serve as edge devices and/or cellular relays to relay communications from the other nodes <NUM>-<NUM> through106-<NUM> and <NUM>-<NUM> through <NUM>-N of the ARA to and from the central office <NUM> via the network(s) <NUM>.

As an example, node <NUM>-N may be representative of each of the nodes <NUM> and includes a radio (e.g., a transceiver) <NUM>, a PLC transceiver <NUM>, a processing unit <NUM>, and a memory <NUM>.

The radio <NUM> may include a radio frequency (RF) transceiver that may be configured to receive RF signals associated with multiple different RF communication technologies (e.g., frequency shift keying (FSK), offset quadrature phase shift keying (OQPSK), orthogonal frequency-division multiplexing (OFDM), code-division multiple access (CDMA), etc.) at a variety of data rates, and transmit RF signals via one or more of a plurality of RF communication technologies. The radio <NUM> may include a multiple protocol receiver and may be configured to listen for a plurality of different RF communication technologies in a parallel fashion across multiple links. The radio <NUM> may also be configured to determine, or facilitate determination of, a received signal strength, such as a "received signal indicator" (RSI) for one or more of the plurality of different RF communication technologies.

In some implementations, each of the nodes <NUM> includes a single radio <NUM> configured to send and receive data on multiple different channels, such as the control channel and multiple data channels of each communication link. The radio <NUM> may also be configured to implement a plurality of different data rates, protocols, signal strengths, and/or power levels. The network architecture <NUM> may represent a heterogeneous network of nodes <NUM>, in that the nodes <NUM> may include different types of nodes (e.g., smart meters, cellular relays, sensors, etc.), different generations or models of nodes, and/or nodes that otherwise are capable of transmitting on different channels and using different communication technologies, data rates, protocols, signal strengths, and/or power levels.

The power line communication (PLC) transceiver <NUM> is configured to transmit and/or receive one or more communication signals on electrical power wiring, including local power wiring and long distance high voltage transmission lines. The PLC transceiver <NUM> may transmit and/or receive different types of power line communications that include one or more PLC communication technologies (e.g., narrowband PLC, broadband PLC, power line digital subscriber line (PDSL), power line telecom (PLT), power line networking (PLN), broadband over power lines (BPL), etc.) having one or more frequency bands, channels, data rates and/or types of modulation that may depend on the propagation characteristics of the power wiring used.

The processing unit <NUM> is coupled to the radio <NUM>, the PLC transceiver <NUM>, and the memory <NUM>, and may include one or more processor(s) <NUM> communicatively coupled to the memory <NUM>. The memory <NUM> may be configured to store one or more software and/or firmware modules <NUM>, which are executable on the processor(s) <NUM> to implement various functions. While the modules are described herein as being software and/or firmware executable on a processor, in other examples, any or all of the modules may be implemented in whole or in part by hardware (e.g., as an application specific integrated circuit (ASIC), a specialized processing unit, digital signal processor, etc.) to execute the described functions. In the example of <FIG>, the memory <NUM> includes any software and/or firmware executable to bring about any function of the node <NUM> as a utility meter and a device within a network of nodes <NUM> including send and receive communications, detect utility consumption, and process data, among other functions of a utility meter.

The memory <NUM> may comprise computer-readable media and may take the form of volatile memory, such as random access memory (RAM) and/or non-volatile memory, such as read only memory (ROM) or flash RAM. Computer-readable media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data for execution by one or more processors of a computing device. Examples of computer-readable media include, but are not limited to, phase change memory (PRAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device. As defined herein, computer-readable media does not include communication media, such as modulated data signals and carrier waves.

The network(s) <NUM> may represent a backhaul network, which may itself comprise a wireless or a wired network, or a combination thereof. The network(s) <NUM> may be a collection of individual networks interconnected with each other and functioning as a single large network (e.g., the Internet and/or one or more intranets). Further, the individual networks may be wireless or wired networks, or a combination thereof.

The central office <NUM> may be implemented by one or more computing devices, such as servers, personal computers, and laptop computers, among others. The one or more computing devices may be equipped with one or more processor(s) communicatively coupled to memory. In some examples, the central office <NUM> includes a centralized meter data management system which performs processing, analysis, storage, and/or management of data received from one or more of the nodes <NUM>. For example, the central office <NUM> may process, analyze, store, and/or manage data obtained from a smart utility meter, sensor, control device, router, regulator, server, relay, switch, valve, and/or other devices included as the nodes <NUM>. Although the example of <FIG> illustrates the central office <NUM> in a single location, in some examples the central office may be distributed amongst multiple locations and/or may be eliminated entirely (e.g., in the case of a highly decentralized distributed computing platform).

Electrical power may be measured by the node <NUM>-N (and other nodes <NUM>) as the power is used or consumed by a consumer. In one example, a transformer (not shown) delivers power to a consumer by an electrical conductor <NUM>. In one example, the quantity of power that is delivered is measured by a metrology unit <NUM> associated with node <NUM>-N. The metrology unit <NUM> associated with node <NUM>-N is able to detect, measure, interrupt, and protect the node <NUM>-N from the power delivered over the conductor <NUM>. The electrical power measured by the metrology unit <NUM> may be transmitted to the central office <NUM>, and the central office <NUM> may be configured to include collection engine (CE) functionality. In one example, aspects of the CE functionality may be distributed, partly or fully, within some or all of the nodes <NUM>. The central office <NUM> and its functionality may be centralized within a utility company, distributed among locations within the network <NUM>, and/or located in a data center location or "cloud" environment.

The node <NUM>-N further includes a load-side voltage detection (LVD) module <NUM>. The LVD module <NUM> serves to detect whether a load-side voltage (e.g., a back-feed voltage) exists on the load-side of the metrology unit <NUM> of the node <NUM>-N. Further, the LVD module <NUM> serves to determine if and when a load-side voltage (LV) disconnect switch <NUM> may be closed to allow electrical power from the utility provider to be provided to the consumer's building to which the node <NUM>-N (e.g., the electrical power meter) is coupled.

The LVD module <NUM> of the node <NUM>-N includes an LVD circuit <NUM>. The LVD circuit <NUM> is described herein in connection with the examples of <FIG> and <FIG>. As indicated in <FIG>, the LVD circuit <NUM> may include a first version <NUM>-<NUM> or a second version <NUM>-<NUM>. In electrical power meter technologies, form <NUM> meter and form <NUM> meter are available for residence and commercial property applications. A form <NUM> meter is a relatively more common meter form and is most commonly used in a120 V/ <NUM> V, single phase three wire service. The form <NUM> meter is commonly found in residential applications as well as many small business or commercial applications. A form <NUM> meter is a self-contained meter that may be used on a few different services including, for example, a <NUM> wire delta three phase service and a single phase service that is pulled off of a three phase transformer. For example, if a <NUM> V/<NUM> V four wire wye transformer feeds the building and the consumer desires only a single phase, two legs and the neutral may be pulled off the transformer to obtain the single phase.

With reference to the various forms of meters described herein, the "form" designation is in practice a two-part identifier. The number indicates how the meter is wired electrically, and the letter suffix denotes the mechanical form factor of the meter. Thus, the systems and methods described herein may be used in an "S" base meter (e.g. form <NUM>, form <NUM>, etc.), an "A"-base meter (e.g. form 2A, form 12A, etc.), or other meter forms. A form <NUM> meter, for example, is electrically identical to a form 2A meter but includes a different mechanical form factor. To refer to a specific electrical form, irrespective of the mechanical form factor of the meter, only the form number is utilized herein.

In the example of <FIG>, the first version <NUM>-<NUM> of the LVD circuit <NUM> is applicable to a form <NUM> meter. In contrast, in the example of <FIG>, the second version <NUM>-<NUM> of the LVD circuit <NUM> is applicable to a form <NUM> meter. The first version <NUM>-<NUM> and the second version <NUM>-<NUM> will be described in more detail herein in connection with <FIG> and <FIG>, respectively.

The node <NUM>-N further includes the load-side voltage (LV) disconnect switch <NUM> mentioned above. In one example, the LV disconnect switch <NUM> may be included as a part of the LVD module <NUM>. In one example, the LV disconnect switch <NUM> may be a separate module or circuit with respect to the LVD module <NUM>. An LV disconnect switch <NUM> is a switch used to disconnect and/or connect/reconnect electrical services to the building to which the node <NUM>-N is coupled. As described herein, the existence of the LV disconnect switch <NUM> within the node <NUM>-N is at least partially the reason for additional regulations and/or standards (e.g., NEMA C12. <NUM>) to be propagated in order to increase safety when operating the node <NUM>-N. In the examples described herein, the LV disconnect switch <NUM> may be opened or closed by a technician located at the node <NUM>-N. In this example, the technician may physically inspect and confirm whether a load-side voltage is applied to the node <NUM>-N by inspecting whether an alternative power source is electrically coupled to the node <NUM>-N. An alternative electrical power source may include, for example, a generator connected to the consumer's building, an alternative power source such as a photovoltaic cell array, electrical cable originating from a neighboring building and utilizing the electrical power supplied to the neighboring building, or by some other means of obtaining electrical power apart from the electrical power utility provider. Thus, the technician, through physical inspection, may remedy the load-side voltage provided by the alternative power source by disconnecting the alternative power source from the load side of the node <NUM>-N.

In one example, however, the LV disconnect switch <NUM> may be opened or closed by a technician sending a signal to the node <NUM>-N from the central office <NUM>, for example, to the node <NUM>-N. In this example, the technician may not be physically located next to the node <NUM>-N and cannot physically inspect and confirm whether a load-side voltage is applied to the node <NUM>-N. Thus, the LVD circuit(s) <NUM> may be used to detect if a load-side voltage is present at the node <NUM>-N.

In the examples described herein, the LV disconnect switch <NUM> may be restricted from closing in instances where the LVD circuit <NUM> of the LVD module <NUM> indicates or detects that a load-side voltage is applied to the load-side of the node <NUM>-N. In one example, a notification may be sent to a technician located at the central office <NUM> or another individual via a computing device. In this example, the notification may be presented on an output device of a computing device and may indicate that a load-side voltage is present at the load-side of the node <NUM>-N. Further, in this example, the technician or other user may be restricted from remotely closing the LV disconnect switch <NUM> via a signal sent to the node <NUM>-N. The manner in which a signal indicating a load-side voltage is present at the load-side of the node <NUM>-N is produced will be described herein in connection with <FIG> and <FIG>.

Having described the environment in which the node <NUM> operates, the physical elements of the node <NUM> (e.g., utility meter) will now be described in connection with <FIG>. Although the nodes <NUM> have been referred to as "nodes" within this description, the nodes <NUM> may also be referred to as a utility metering unit, a utility meter, or a metrology device, and will be referred to as a utility meter in connection with <FIG> to invoke the physical aspects of the utility meter <NUM>.

<FIG> illustrates a load-side voltage detection (LVD) circuit <NUM> for a form <NUM> utility meter <NUM>, according to an example of the principles described herein. The LVD circuit <NUM> of the LVD module <NUM> of <FIG> is the first version <NUM>-<NUM> that provides load-side detection for the form <NUM> utility meter <NUM>. The first version <NUM>-<NUM> of the circuit includes a pulse generator <NUM> created by the components to the right of test point <NUM>. On a positive swing of the input voltage (and in instances where the input voltage is above a first threshold), a first capacitor <NUM> charges up to a maximum level set by a clamp voltage of a first diode <NUM> in parallel with the first capacitor <NUM>. In contrast, on a negative swing of the input voltage (and in instances where the input voltage is above a second threshold) a first transistor <NUM> turns on, which causes a second transistor <NUM> to turn on and discharge the capacitance held by the first capacitor <NUM> though an optoisolator <NUM>, creating a pulse on the isolated output <NUM>. The presence of the optoisolator <NUM> in the circuit of <FIG> creates an isolation boundary (e.g., isolation voltage) in the output signal. The optoisolator <NUM> connects input and output sides with a beam of light modulated by input current, and transforms the input signal into light, sends it across a dielectric channel, captures light on the output side, and transforms the light back into electric signal. In one example, the optoisolator <NUM> may be unidirectional and cannot transmit power. The optoisolator <NUM> may modulate the flow of energy already present on the output side.

The output of the optoisolator <NUM> may be fed to an LVD input of a metrology ASIC (not shown) such as a MI6 metrology ASIC and indicates the presence of a voltage on one or both load-side terminals of the utility meter <NUM>. Further, in the example of <FIG>, the first version <NUM>-<NUM> of the circuit utilizes a virtual ground signal provided by a voltage divider <NUM> to emulate a neutral (e.g., earth ground) which is not present in a form <NUM> utility meter. The first version <NUM>-<NUM> of the circuit may, for example, monitor each of the two load-side voltage terminals independently. Further, the first version <NUM>-<NUM> of the circuit may have different threshold voltages depending on whether the two load-side terminal voltages are in-phase or out-of-phase. The function and purpose of the various elements of the first version <NUM>-<NUM> of the circuit will now be described in more detail.

In instances where test point <NUM> is at a positive voltage during a positive swing of the input voltage, the first diode <NUM> is reverse biased such that it blocks current and forces the current to flow through the capacitor <NUM> and to the second diode <NUM>. This results in the capacitor <NUM> charging. In instances where test point <NUM> is at a negative voltage during a negative swing of the input voltage, the second diode <NUM> is reversed biased and the first diode <NUM> is forward biased. This results in the negative voltage between the capacitor <NUM> and the first transistor <NUM> such that the first transistor <NUM> and the second transistor <NUM> as mentioned above are turned on. In this manner, the capacitive charge held by the capacitor <NUM> is dumped into the optoisolator <NUM>. The diode (e.g., a light-emitting diode (LED)) in the optoisolator <NUM> is forward biased by the voltage and causes an isolated output pulse to be output by the optoisolator <NUM>. In this manner, the capacitor <NUM> charges on the positive voltage swing, and dumps its charge into the optoisolator <NUM> on the negative voltage swing.

The first version <NUM>-<NUM> of the circuit includes a first load-side voltage (LV) terminal <NUM> that carries a first load designated as "LOAD_A," meaning load-side A. Thus, the first LV terminal <NUM> may carry phase A of the load coupled to the load side of the first version <NUM>-<NUM> of the utility meter <NUM>. A second LV terminal <NUM> may carry a second load designated as "LOAD _C," meaning load-side C. Thus, the second LV terminal <NUM> may carry phase C of the load coupled to the load side of the first version <NUM>-<NUM> of the utility meter <NUM>. The first LV terminal <NUM> includes a plurality of first resistors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-M where M is any integer greater than or equal to <NUM> (collectively referred to herein as first resistor(s) <NUM> unless specifically addressed otherwise). In the example of <FIG>, six (<NUM>) first resistors <NUM> are included in the first LV terminal <NUM> and are coupled in series. However, any number of first resistors <NUM> may be included in the first LV terminal <NUM>. Similarly, the second LV terminal <NUM> includes a plurality of second resistors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-P where P is any integer greater than or equal to <NUM> (collectively referred to herein as second resistor(s) <NUM> unless specifically addressed otherwise). In the example of <FIG>, six (<NUM>) second resistors <NUM> are included in the second LV terminal <NUM> and are coupled in series. However, any number of second resistors <NUM> may be included in the second LV terminal <NUM>.

The first version <NUM>-<NUM> of the circuit further includes a virtual ground (designated as "VGND" in <FIG>). The virtual ground may be created by a voltage divider <NUM> where the voltage divider is any passive linear circuit that produces an output voltage at test point <NUM> that is a fraction of the voltage at LINE_A. LINE_A Voltage division is the result of distributing the input voltage among the voltage divider resistors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-R of the voltage divider, where R is any integer greater than or equal to <NUM> (collectively referred to herein as voltage divider resistor(s) <NUM> unless specifically addressed otherwise). The voltage divider includes the voltage divider resistors <NUM> connected in series, with the voltage at LINE_A applied across the voltage divider resistors <NUM> and the output voltage emerging from the connection between them at test point <NUM>. VGND is a voltage that approximates the subtraction of LINE_C from LINE_A, which should approximate <NUM> volts relative to earth ground (neutral). VGND is coupled to the voltage divider <NUM> at test point <NUM>. In one example, the voltage divider resistors <NUM> may have a resistive value of <NUM> megaohms (MΩ).

In order to function as a load-side voltage detector, the sum of the first resistor values <NUM> of the first LV terminal <NUM> and the sum of the second resistor values <NUM> of the second LV terminal <NUM> have total resistance values that are different. The difference in resistance between the first resistors <NUM> and the second resistors <NUM> results in a clear detection of a load-side voltage. If, for example, the sum of the resistance values of the first resistors <NUM> and the sum of the second resistor values <NUM> were the same, a virtual ground would be created, and detection of the load-side voltage would be impossible. Thus, with the total resistance values of the first resistors <NUM> and the total resistance values of the second resistors <NUM> being different and in instances where the same voltage is applied to both the first LV terminal <NUM> and the second LV terminal <NUM> with respect to virtual ground (e.g., located at test point <NUM>), the output detected at test point <NUM> will be a voltage value other than ground. In one example, the resistance values of each of the first resistors <NUM> may be <NUM> kiloohms (kΩ) and the resistance values of each of the second resistors <NUM> may be <NUM> kΩ. However, any differentiation in resistive values may serve to allow for a detection of a load-side voltage at either or both of the first LV terminal <NUM> and the second LV terminal <NUM>, and even in instances where the voltages at the first LV terminal <NUM> and the second LV terminal <NUM> are in phase or out of phase.

In this manner, if there is voltage present in either the first LV terminal <NUM> (coupled to LOAD_A or A phase voltage) or the second LV terminal <NUM> (coupled to LOAD_C or C phase voltage), or if there is voltage present on both the first LV terminal <NUM> and the second LV terminal <NUM> (even if the voltages are the same), the first version <NUM>-<NUM> of the circuit can detect that load-side voltage. Further, any load-side voltage at the first LV terminal <NUM> and/or the second LV terminal <NUM> may be detected irrespective of those voltage values, the phases of the voltages, or the presence of a voltage at one LV terminal <NUM>, <NUM> and not the other. Thus, in any scenario of a load-side voltage being present on the utility meter <NUM>, that load-side voltage can be detected and closure of the LV disconnect switch <NUM> may be restricted and/or notification to not close the LV disconnect switch <NUM> may be transmitted to a technician. The ability to detect a load-side voltage in the manner provided by the first version <NUM>-<NUM> of the LVD circuit <NUM> increases safety in operating the utility meter <NUM> by reducing the potential for damage to or loss of property and reducing or eliminating the potential for a technician or other individual from being harmed by any resulting electrical shock or electricity-related fires that may result if the LV disconnect switch <NUM> were allowed to close in the presence of a load-side voltage at the LV terminals <NUM>, <NUM>.

As described above, a voltage may be detected at either or both of the LV terminals <NUM>, <NUM> and that voltage may be detected by and may be used to drive the pulse generator <NUM>. In one example, the voltage(s) from either or both of the LV terminals <NUM>, <NUM> may be above a number of thresholds in order to activate the pulse generator <NUM> and allow the pulse generator <NUM> to function. These thresholds may define voltages referred to as load-side closing (LSC) threshold voltages below which the utility meter <NUM> may recognize load side conditions as safe. For descriptive purposes, these threshold(s) may be referred to as a "back feed voltage threshold" or an "LSC threshold. " In one example where the voltage sensed at test point <NUM> is below the threshold, the risk of damage to property or life may be de minimis or non-existent and it may be safe to close the LV disconnect switch <NUM>. In one example, the threshold(s) may be set at, for example, approximately <NUM> volts (V). In this example, if LOAD_A or LOAD_C is below <NUM> V with respect to the virtual ground (VGND) created by the voltage divider <NUM>, the LV disconnect switch <NUM> will be allowed to close. In contrast, if LOAD_A or LOAD_C is above <NUM> V with respect to the virtual ground (VGND) created by the voltage divider <NUM>, the LV disconnect switch <NUM> will not be allowed to close. Examples of thresholds that may be set for different scenarios include those thresholds defined in the NEMA C12. <NUM> at tables <NUM> through <NUM> (and associated <FIG>) of that standard.

As a voltage is detected at test point <NUM> above the threshold(s), the pulse generator <NUM> begins to operate and produce a pulse that is fed to an LVD input at LVD of <FIG> of the metrology ASIC (not shown) to detect the presence of the voltage on one or both LV terminals <NUM>, <NUM> of the utility meter <NUM>. The input voltage at test point <NUM> is fed into the pulse generator <NUM> to drive the pulse generator <NUM>.

The pulse generator <NUM> of the first version <NUM>-<NUM> of the LVD circuit <NUM> includes a first diode <NUM> in series with a second diode <NUM>. The triangles in the symbols of the diodes <NUM>, <NUM> point to the forward direction (e.g., in the direction of conventional current flow). In one example, the diodes <NUM>, <NUM> may be Schottky diodes. In one example, the first diode <NUM> and the second diode <NUM> have a clamp voltage rating of <NUM> V.

A first capacitor <NUM> included in the pulse generator <NUM> may be coupled in parallel with the first diode <NUM> and may have a capacitance rating of <NUM> microfarad (µF). During a positive swing of the voltage sensed at test point <NUM>, the capacitor <NUM> charges up to a maximum voltage defined by the clamp voltage of the first diode <NUM> (e.g., <NUM> V). During a negative swing of the voltage sensed at test point <NUM>, the capacitor <NUM> is then discharged through the first transistor <NUM>, turning on the first transistor <NUM>, and through the second transistor <NUM>, turning on the second transistor <NUM>. In one example, the first transistor <NUM> and the second transistor <NUM> may be any type transistor such as, for example, a bipolar junction transistor (BJT), a field-effect transistor (FET), or a metal-oxide semiconductor field-effect transistor (MOSFET), among other types of transistors. In one example, the first transistor <NUM> and the second transistor <NUM> may be included as one or more integrated circuits in order to save space on a printed circuit board (PCB), save time in manufacturing the utility meter <NUM> and/or the LVD module <NUM>, or other purpose. In one example, the first transistor <NUM> is an NPN-type BJT transistor. Further, in one example, the second transistor <NUM> is a PNP-type transistor.

Once turned on, the first transistor <NUM> and the second transistor <NUM> provide a signal to the optoisolator <NUM>. The optoisolator <NUM> may be any electronic device that transfers electrical signals between two isolated circuits by using electromagnetic radiation (e.g., light). The optoisolator <NUM> prevents high voltages from negatively affecting the system receiving the signal such as the metrology ASIC (not shown) (e.g., an MI6 metrology ASIC). In one example, the optoisolator <NUM>, as mentioned above, includes a light-emitting diode (LED) and a phototransistor. In another example, the optoisolator <NUM> includes an LED-photodiode, an LED-light activated silicon controlled rectifier (LASCR), a lamp-photoresistor pair, or other types of optoisolators. The optoisolator <NUM> may transfer digital (e.g., on-off) signals or analog signals. The output of the optoisolator <NUM> is a pulse on the isolated output.

The pulse generator <NUM> also includes a pull-down resistor <NUM> to ensure that the LVD output is <NUM> V unless a pulse output is received from the optoisolator <NUM>. Because the optoisolator <NUM> does not include a component that can pull the signal down to <NUM> V, the pull-down resistor <NUM> can pull down that voltage until a pulse (e.g., with a voltage such as <NUM> V) is present on the output of the optoisolator <NUM>. In one example, the pull-down resistor <NUM> may be a <NUM> kΩ resistor.

The capacitor <NUM> functions as a pulse spreader. The pulse that is output by the optoisolator <NUM> is a relatively brief pulse with a positive polarity, output high active state, and in order for the metrology ASIC (not shown) (e.g., an MI6 metrology ASIC) to detect the pulses from the optoisolator <NUM>, the capacitor <NUM> holds a charge created by the output pulse of the optoisolator <NUM> and spreads the pulse width of the output pulse to a width that the metrology ASIC (not shown) (e.g., an MI6 metrology ASIC) can detect and recognize. Also, the capacitor <NUM> serves to reduce noise on the output pulse from the optoisolator <NUM> (e.g., radio frequency (RF) filtering).

In some instances, LOAD_A and LOAD_C may be in-phase or out-of-phase with respect to one another. In an instance where LOAD_A and LOAD_C are in-phase, the voltage sensed at test point <NUM> is increased and, in turn, reduces the input voltage required to make the pulse generator <NUM> operate. In contrast, in instances where LOAD_A and LOAD_C are out-of-phase, the two loads would have to be at a higher level in order to produce enough voltage at test point <NUM> in order to cause the pulse generator <NUM> to operate. Stated another way, in instances where LOAD_A and LOAD_C are in-phase, their respective voltages add together and in instances where LOAD_A and LOAD_C are out-of-phase, their respective voltages subtract from one another. Thus, because each of the first LV terminal <NUM> and the second LV terminal <NUM> may be independently analyzed due to the inclusion of the voltage divider <NUM> in the first version <NUM>-<NUM> of the LVD circuit <NUM>, the in-phase or out-of-phase state of LOAD_A and LOAD_C is irrelevant.

<FIG> illustrates an LVD circuit for a form <NUM> utility meter <NUM>, according to an example of the principles described herein. The LVD circuit <NUM> of the LVD module <NUM> of <FIG> is the second version <NUM>-<NUM> that provides load-side detection for the form <NUM> utility meter <NUM>. The form <NUM> utility meter <NUM> may include two voltages with respect to neutral that may not be perfectly opposing, but may be offset by, for example, <NUM> degrees (rather than <NUM> degrees) out-of-phase. For example, for a <NUM> V input, instead of seeing <NUM> V between LOAD_A and LOAD_C, approximately <NUM> V would be sensed. In the form <NUM> utility meter <NUM>, a connection to neutral is required in order to make an accurate measurement of electrical energy consumption as performed by the utility meter <NUM>. The form <NUM> utility meter <NUM> provides for an easier way to balance loads on the incoming utility service.

The second version <NUM>-<NUM> of the circuit includes a pulse generator <NUM> created by the components to the right of test point <NUM>. Further, the second version <NUM>-<NUM> of the circuit includes a first LV terminal <NUM> and a second LV terminal <NUM> as will be described in more detail below. However, unlike the first version <NUM>-<NUM> of the LVD module <NUM> of <FIG>, the second version <NUM>-<NUM> of the LVD module <NUM> of <FIG> does not include a voltage divider <NUM>, but is, instead, grounded via a number of mains ground connections designated as MGND and having neutral potential.

The second version <NUM>-<NUM> of the circuit may be thought of as two separate voltage detection circuits which operate independently when not considering resistors <NUM>-<NUM> and <NUM>-<NUM>. Resistors <NUM>-<NUM> and <NUM>-<NUM> are included so that two phases either work together or against one another depending on whether the two voltages at the first LV terminal <NUM> and the second LV terminal <NUM> are in-phase or out-of-phase. Further, in a similar manner as described above in connection with the form <NUM> utility meter <NUM> and its first version <NUM>-<NUM> of the circuit, the form <NUM> utility meter <NUM> and its second version <NUM>-<NUM> of the circuit, the detection thresholds are changed based on the phase between the first LV terminal <NUM> and the second LV terminal <NUM>.

The second version <NUM>-<NUM> of the circuit includes a first load-side voltage (LV) terminal <NUM> that carries a first load designated as "LOAD_A," meaning load-side A. Thus, the first LV terminal <NUM> may carry phase A of the load coupled to the load side of the second version <NUM>-<NUM> of the utility meter <NUM>. A second LV terminal <NUM> may carry a second load designated as "LOAD _C," meaning load-side C. Thus, the second LV terminal <NUM> may carry phase C of the load coupled to the load side of the second version <NUM>-<NUM> of the utility meter <NUM>. The first LV terminal <NUM> includes a plurality of first resistors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-s where s is any integer greater than or equal to <NUM> (collectively referred to herein as first resistor(s) <NUM> unless specifically addressed otherwise). In the example of <FIG>, eight (<NUM>) first resistors <NUM> are included in the first LV terminal <NUM> and are coupled in series. However, any number of first resistors <NUM> may be included in the first LV terminal <NUM>. Similarly, the second LV terminal <NUM> includes a plurality of second resistors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>,. , <NUM>-T where T is any integer greater than or equal to <NUM> (collectively referred to herein as second resistor(s) <NUM> unless specifically addressed otherwise). In the example of <FIG>, eight (<NUM>) second resistors <NUM> are included in the second LV terminal <NUM> and are coupled in series. However, any number of second resistors <NUM> may be included in the second LV terminal <NUM>.

In order to function as a load-side voltage detector, the first resistors <NUM> of the first LV terminal <NUM> and the second resistors <NUM> of the second LV terminal <NUM> do not require that their respective resistance values be different unlike the example of <FIG>. Because each LV terminal <NUM>, <NUM> is electrically coupled to ground (e.g., MGND), their respective voltages may be independently measured which results in a clear detection of a load-side voltage at either LV terminals <NUM>, <NUM>. In one example, the resistance values of each of the first resistors <NUM> and the second resistors <NUM> may be <NUM> kiloohms (kΩ). However, any resistive values may serve to allow for a detection of a load-side voltage at either or both of the first LV terminal <NUM> and the second LV terminal <NUM>, and even in instances where the voltages at the first LV terminal <NUM> and the second LV terminal <NUM> are in phase or out of phase.

In this manner, if there is voltage present in either the first LV terminal <NUM> (coupled to LOAD_A or A phase voltage) or the second LV terminal <NUM> (coupled to LOAD_C or C phase voltage), or if there is voltage present on both the first LV terminal <NUM> and the second LV terminal <NUM> (even if the voltages are the same), the second version <NUM>-<NUM> of the circuit can detect that load-side voltage. Further, any load-side voltage at the first LV terminal <NUM> and/or the second LV terminal <NUM> may be detected irrespective of those voltage values, the phases of the voltages, or the presence of a voltage at one LV terminal <NUM>, <NUM> and not the other. Thus, in any scenario of a load-side voltage being present on the utility meter <NUM>, that load-said voltage can be detected, and closure of the LV disconnect switch <NUM> may be restricted and/or notification to not close the LV disconnect switch <NUM> may be transmitted to a technician. The ability to detect a load-side voltage in the manner provided by the second version <NUM>-<NUM> of the LVD circuit <NUM> increases safety in operating the utility meter <NUM> by reducing the potential for damage to or loss of property and reducing or eliminating the potential for a technician or other individual from being harmed by any resulting electrical shock or electricity-related fires that may result if the LV disconnect switch <NUM> were allowed to close in the presence of a load-side voltage at the LV terminals <NUM>, <NUM>.

As described above, a voltage may be detected at either or both of the LV terminals <NUM>, <NUM> and that voltage may be detected by and may be used to drive the pulse generator <NUM>. In one example, the voltage(s) from either or both of the LV terminals <NUM>, <NUM> may be above a number of thresholds in order to activate the pulse generator <NUM> and allow the pulse generator <NUM> to function. These thresholds may define voltages referred to as load-side closing (LSC) threshold voltages below which the utility meter <NUM> may recognize load side conditions as safe. For descriptive purposes, these threshold(s) may be referred to as a "back feed voltage threshold" or an "LSC threshold. " In one example where the voltage sensed at test point <NUM> is below the threshold, the risk of damage to property or life may be de minimis or non-existent and it may be safe to close the LV disconnect switch <NUM>. In one example, the threshold(s) may be set at, for example, approximately <NUM> volts (V). In this example, if LOAD_A or LOAD_C is below <NUM> V with respect to ground (e.g., MGND), the LV disconnect switch <NUM> will be allowed to close. In contrast, if LOAD_A or LOAD_C is above <NUM> V with respect to ground (e.g., MGND), the LV disconnect switch <NUM> will not be allowed to close. Examples of thresholds that may be set for different scenarios include those thresholds defined in the NEMA C12. <NUM> at tables <NUM> through <NUM> (and associated <FIG>) of that standard.

As a voltage is detected at test point <NUM> above the threshold(s), the pulse generator <NUM> begins to operate and produce a pulse that is fed to an LVD input at LVD of <FIG> of the metrology ASIC (not shown) to detect the presence of the voltage on one or both load-side terminals <NUM>, <NUM> of the utility meter <NUM>. The input voltage at test point <NUM> is fed into the pulse generator <NUM> to drive the pulse generator <NUM>.

The pulse generator <NUM> of the second version <NUM>-<NUM> of the LVD circuit <NUM> includes a first dividing resistor <NUM>-<NUM> and a second dividing resistor <NUM>-<NUM> that serve to create a reference voltage and/or reduce the magnitude of the input voltage from the first LV terminal <NUM> and a second LV terminal <NUM> so the voltage can be measured. The first dividing resistor <NUM>-<NUM> and the second dividing resistor <NUM>-<NUM> may create the reference voltage with respect to ground (e.g., MGND) as depicted in <FIG>.

A first diode <NUM> and a second diode <NUM> may be electrically coupled in series with a respective one of the first dividing resistor <NUM>-<NUM> and the second dividing resistor <NUM>-<NUM>. Further, a third diode <NUM> is electrically coupled to the first diode <NUM> in series, and a fourth diode <NUM> is electrically coupled to the second diode <NUM> in series. Again, the triangles in the symbols of the diodes <NUM>, <NUM> point to the forward direction (e.g., in the direction of conventional current flow). As indicated above, neutral or ground exists within the circuit and is located between the third diode <NUM> and the fourth diode <NUM>.

Resistors <NUM>-<NUM> and <NUM>-<NUM> serve to reduce current flow to respective transistors <NUM>-<NUM>, <NUM>-<NUM>, and/or adjust signal levels flow to the respective transistors <NUM>-<NUM>, <NUM>-<NUM>. The respective transistors <NUM>-<NUM>, <NUM>-<NUM> may include any type transistor such as, for example, a bipolar junction transistor (BJT), a field-effect transistor (FET), or a metal-oxide semiconductor field-effect transistor (MOSFET), among other types of transistors. In one example, the respective transistors <NUM>-<NUM>, <NUM>-<NUM> may be included as one or more integrated circuits in order to save space on a printed circuit board (PCB), save time in manufacturing the utility meter <NUM> and/or the LVD module <NUM>, or other purpose. In one example, the respective transistors <NUM>-<NUM>, <NUM>-<NUM> may include MOSFETS. A first capacitor <NUM> and the second capacitor <NUM> are located between the respective resistors <NUM>-<NUM> and <NUM>-<NUM> and the respective transistors <NUM>-<NUM>, <NUM>-<NUM>. The first capacitor <NUM> and the second capacitor <NUM> serve as noise filters. In one example, the first capacitor <NUM> and the second capacitor <NUM> may have a capacitance of <NUM> picofarads (pF).

Further, a first pull-down resistor <NUM> and a second pull-down resistor <NUM> are also located between the respective resistors <NUM>-<NUM> and <NUM>-<NUM> and the respective transistors <NUM>-<NUM>, <NUM>-<NUM>. Resistors <NUM>-<NUM>, <NUM>-<NUM><NUM>, and <NUM> serve as voltage dividers to adjust the load side voltage detection thresholds. In one example, the first pull-down resistor <NUM> and the second pull-down resistor <NUM> may have a resistance of <NUM> kΩ.

A first MOSFET <NUM>-<NUM> and a second MOSFET <NUM>-<NUM> are located in series with the resistors <NUM>-<NUM> and <NUM>-<NUM>. The output of the first MOSFET <NUM>-<NUM> and a second MOSFET <NUM>-<NUM> may be fed to an LVD input of a metrology ASIC (not shown) such as a MI6 metrology ASIC and indicates the presence of a voltage on one or both load-side terminals of the utility meter <NUM>. Resistor <NUM> may serve to reduce current flow and/or adjust signal levels flow in a similar manner as resistors <NUM>-<NUM> and <NUM>-<NUM>.

In a similar manner as presented above in connection with the first version <NUM>-<NUM> of the LVD module <NUM> of <FIG>, in instances where a voltage is sensed at either the first LV terminal <NUM> (e.g., LOAD_A is present) or the second LV terminal <NUM> (e.g., LOAD_C is present), the voltage(s) will cause pulses to be detectable on the drain of either or both of the transistors <NUM>-<NUM>, <NUM>-<NUM>. In instances where LOAD_A and LOAD_C are in phase, the two loads work together to reduce the threshold required to detect the voltages due to the inclusion of resistors <NUM>-<NUM> and <NUM>-<NUM>. In instances where LOAD_A and LOAD_C are out of phase, the two loads work against one another and a relatively higher voltage is required to be detectable on the collectors of either or both of the transistors <NUM>-<NUM>, <NUM>-<NUM>.

Having described the examples of <FIG> and <FIG>, it is noted that the LVD pulses output by the first version <NUM>-<NUM> of the LVD circuit <NUM> depicted in <FIG> are positive polarity pulses or output high pulses where the output LVD pulse is normally low (e.g., approximately <NUM> V) and is high (e.g., approximately <NUM> V) when a pulse is output by the optoisolator <NUM>. In contrast, the LVD pulses output by the second version <NUM>-<NUM> of the LVD circuit <NUM> depicted in <FIG> are of opposite polarity compared to the example of <FIG>. Thus, the LVD pulses output by the second version <NUM>-<NUM> of the LVD circuit <NUM> depicted in <FIG> may be described as negative polarity pulses or output low pulses where the output LVD pulse is normally high (e.g., approximately <NUM> V) and is low (e.g., approximately <NUM> V) when a pulse is output by the transistors <NUM>-<NUM>, <NUM>-<NUM>. However, either version <NUM>-<NUM>, <NUM>-<NUM> of the LVD circuit <NUM> depicted in <FIG> and <FIG> may be altered such that they are low active (e.g., negative polarity) or high active (e.g., positive polarity).

<FIG> illustrates a load-side voltage (LV) disconnect switch <NUM> of a utility meter <NUM>, according to an example of the principles described herein. The LV disconnect switch <NUM> serves to connect, disconnect, and/or reconnect electrical power services to a residence or commercial building as described herein. In the event that a back-feed voltage is detected by the first version <NUM>-<NUM> or the second version <NUM>-<NUM> of the LVD circuit <NUM> depicted in <FIG> and <FIG>, respectively, the LV disconnect switch <NUM> may be precluded from closing and allowing electrical current to flow via the utility meter <NUM>. In other words, LVD circuit <NUM> of the LVD module <NUM> serves to determine if and when the LV disconnect switch <NUM> may be closed to allow electrical power from the utility provider to be provided to the consumer's building to which the node <NUM>-N (e.g., the electrical power meter or utility meter as referred to herein) is coupled.

The LV disconnect switch <NUM> may include a line side designated as "A", and a corresponding "LOAD_A" located on the load side of the utility meter <NUM>. This LOAD_A line couples to the first LV terminals <NUM>, <NUM> of <FIG> and <FIG>, respectively. Similarly, the LV disconnect switch <NUM> may include a line side designated as "C", and a corresponding "LOAD_C" located on the load side of the utility meter <NUM>. This LOAD_C line couples to the second LV terminals <NUM>, <NUM> of <FIG> and <FIG>, respectively. A first resistor <NUM> is included between the line side C and a first switch <NUM> and a second resistor <NUM> is included between the line side A and a second switch <NUM>. The switches allow electricity to flow to the utility meter <NUM> and may be controlled by an actuator <NUM> coupled to the switches <NUM>, <NUM> via a control line <NUM>. In this manner, a signal may be sent from, for example, the central office <NUM>, to instruct the actuator <NUM> to disconnect or connect/reconnect the electricity from or to the utility meter <NUM>.

<FIG> illustrates a computing system diagram illustrating a configuration for a data center that may be utilized to implement aspects of the technologies disclosed herein. The example data center <NUM> shown in <FIG> includes several server computers 502A-502F (which might be referred to herein singularly as "a server computer <NUM>" or in the plural as "the server computers <NUM>") for providing computing resources. In some examples, the resources and/or server computers <NUM> may include, or correspond to, any type of networked device described herein including, for example, the central office <NUM> and the nodes <NUM>. Although described as servers, the server computers <NUM> may comprise any type of networked device, such as servers, switches, routers, hubs, bridges, gateways, modems, repeaters, access points, etc..

The server computers <NUM> may be standard tower, rack-mount, or blade server computers configured appropriately for providing computing resources. In some examples, the server computers <NUM> may provide computing resources <NUM> including data processing resources such as VM instances or hardware computing systems, database clusters, computing clusters, storage clusters, data storage resources, database resources, networking resources, virtual private networks (VPNs), and others. Some of the server computers <NUM> may also be configured to execute a resource manager <NUM> capable of instantiating and/or managing the computing resources. In the case of VM instances, for example, the resource manager <NUM> may be a hypervisor or another type of program configured to enable the execution of multiple VM instances on a single server computer <NUM>. Server computers <NUM> in the data center <NUM> may also be configured to provide network services and other types of services.

In the example data center <NUM> shown in <FIG>, an appropriate LAN <NUM> is also utilized to interconnect the server computers 502A-502F. It may be appreciated that the configuration and network topology described herein has been greatly simplified and that many more computing systems, software components, networks, and networking devices may be utilized to interconnect the various computing systems disclosed herein and to provide the functionality described above. Appropriate load balancing devices or other types of network infrastructure components may also be utilized for balancing a load between data centers <NUM>, between each of the server computers 502A-502F in each data center <NUM>, and, potentially, between computing resources in each of the server computers <NUM>. It may be appreciated that the configuration of the data center <NUM> described with reference to <FIG> is merely illustrative and that other implementations may be utilized.

In some examples, the server computers <NUM> and or the computing resources <NUM> may each execute/host one or more tenant containers and/or virtual machines (VMs) to perform techniques described herein including, for example, instructing a node <NUM> to disconnect or connect/reconnect electrical power to the node <NUM> via the LV disconnect switch <NUM>.

In some examples, the data center <NUM> may provide computing resources, like tenant containers, VM instances, VPN instances, and storage, on a permanent or an as-needed basis. Among other types of functionality, the computing resources provided by a cloud computing network may be utilized to implement the various services and techniques described above. The computing resources <NUM> provided by the cloud computing network may include various types of computing resources, such as data processing resources like tenant containers and VM instances, data storage resources, networking resources, data communication resources, network services, VPN instances, and the like.

Each type of computing resource <NUM> provided by the cloud computing network may be general-purpose or may be available in a number of specific configurations. For example, data processing resources may be available as physical computers or VM instances in a number of different configurations. The VM instances may be configured to execute applications, including web servers, application servers, media servers, database servers, some or all of the network services described above, and/or other types of programs. Data storage resources may include file storage devices, block storage devices, and the like. The cloud computing network may also be configured to provide other types of computing resources <NUM> not mentioned specifically herein.

The computing resources <NUM> provided by a cloud computing network may be enabled in one example by one or more data centers <NUM> (which might be referred to herein singularly as "a data center <NUM>" or in the plural as "the data centers <NUM>"). The data centers <NUM> are facilities utilized to house and operate computer systems and associated components. The data centers <NUM> typically include redundant and backup power, communications, cooling, and security systems. The data centers <NUM> may also be located in geographically disparate locations. One illustrative example for a data center <NUM> that may be utilized to implement the technologies disclosed herein is described herein with regard to, for example, <FIG>.

<FIG> illustrates a computer architecture diagram showing an example computer hardware architecture <NUM> for implementing a computing device that may be utilized to implement aspects of the various technologies presented herein. The computer hardware architecture <NUM> shown in <FIG> illustrates the central office <NUM>, the nodes <NUM> (e.g., utility meters), and/or other systems or devices associated with the central office <NUM>, the nodes <NUM> (e.g., utility meters) and/or remote from the central office <NUM>, the nodes <NUM> (e.g., utility meters), a workstation, a desktop computer, a laptop, a tablet, a network appliance, an e-reader, a smartphone, or other computing device, and may be utilized to execute any of the software components presented herein. The computer <NUM> may, in some examples, correspond to a network device (e.g., central office <NUM>, the nodes <NUM> (e.g., utility meters) and associated devices) described herein, and may comprise networked devices such as servers, switches, routers, hubs, bridges, gateways, modems, repeaters, access points, etc..

The computer <NUM> includes a baseboard <NUM>, or "motherboard," which is a printed circuit board to which a multitude of components or devices may be connected by way of a system bus or other electrical communication paths. In one illustrative configuration, one or more central processing units (CPUs) <NUM> operate in conjunction with a chipset <NUM>. The CPUs <NUM> may be standard programmable processors that perform arithmetic and logical operations necessary for the operation of the computer <NUM>.

These basic switching elements may be combined to create more complex logic circuits, including registers, adders-subtractors, arithmetic logic units, floating-point units, and the like.

The chipset <NUM> provides an interface between the CPUs <NUM> and the remainder of the components and devices on the baseboard <NUM>. The chipset <NUM> may provide an interface to a RAM <NUM>, used as the main memory in the computer <NUM>. The chipset <NUM> may further provide an interface to a computer-readable storage medium such as a read-only memory (ROM) <NUM> or non-volatile RAM (NVRAM) for storing basic routines that help to startup the computer <NUM> and to transfer information between the various components and devices. The ROM <NUM> or NVRAM may also store other software components necessary for the operation of the computer <NUM> in accordance with the configurations described herein.

The computer <NUM> may operate in a networked environment using logical connections to remote computing devices and computer systems through a network, such as the network(s) <NUM>. The chipset <NUM> may include functionality for providing network connectivity through a Network Interface Controller (NIC) <NUM>, such as a gigabit Ethernet adapter. The NIC <NUM> is capable of connecting the computer <NUM> to other computing devices within the central office <NUM>, the nodes <NUM> (e.g., utility meters) and external to the central office <NUM>, the nodes <NUM> (e.g., utility meters). It may be appreciated that multiple NICs <NUM> may be present in the computer <NUM>, connecting the computer to other types of networks and remote computer systems. In some examples, the NIC <NUM> may be configured to perform at least some of the techniques described herein, such as sending of data or instructions, and/or other techniques described herein.

The computer <NUM> may be connected to a storage device <NUM> that provides non-volatile storage for the computer. The storage device <NUM> may store an operating system <NUM>, programs <NUM>, and data, which have been described in greater detail herein. The storage device <NUM> may be connected to the computer <NUM> through a storage controller <NUM> connected to the chipset <NUM>. The storage device <NUM> may consist of one or more physical storage units. The storage controller <NUM> may interface with the physical storage units through a serial attached SCSI (SAS) interface, a serial advanced technology attachment (SATA) interface, a fiber channel (FC) interface, or other type of interface for physically connecting and transferring data between computers and physical storage units.

The computer <NUM> may store data on the storage device <NUM> by transforming the physical state of the physical storage units to reflect the information being stored. The specific transformation of physical state may depend on various factors, in different examples of this description. Examples of such factors may include, but are not limited to, the technology used to implement the physical storage units, whether the storage device <NUM> is characterized as primary or secondary storage, and the like.

For example, the computer <NUM> may store information to the storage device <NUM> by issuing instructions through the storage controller <NUM> to alter the magnetic characteristics of a particular location within a magnetic disk drive unit, the reflective or refractive characteristics of a particular location in an optical storage unit, or the electrical characteristics of a particular capacitor, transistor, or other discrete component in a solid-state storage unit. Other transformations of physical media are possible without departing from the scope and spirit of the present description, with the foregoing examples provided only to facilitate this description. The computer <NUM> may further read information from the storage device <NUM> by detecting the physical states or characteristics of one or more particular locations within the physical storage units.

In addition to the storage device <NUM> described above, the computer <NUM> may have access to other computer-readable storage media to store and retrieve information, such as program modules, data structures, or other data. It may be appreciated by those skilled in the art that computer-readable storage media is any available media that provides for the non-transitory storage of data and that may be accessed by the computer <NUM>. In some examples, the operations performed by the central office <NUM>, the nodes <NUM> (e.g., utility meters) and or any components included therein, may be supported by one or more devices similar to computer <NUM>. Stated otherwise, some or all of the operations performed by the central office <NUM>, the nodes <NUM> (e.g., utility meters), and or any components included therein, may be performed by one or more computer devices operating in a cloud-based arrangement.

By way of example, and not limitation, computer-readable storage media may include volatile and non-volatile, removable and non-removable media implemented in any method or technology. Computer-readable storage media includes, but is not limited to, RAM, ROM, erasable programmable ROM (EPROM), electrically-erasable programmable ROM (EEPROM), flash memory or other solid-state memory technology, compact disc ROM (CD-ROM), digital versatile disk (DVD), high definition DVD (HD-DVD), BLU-RAY, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store the desired information in a non-transitory fashion.

As mentioned briefly above, the storage device <NUM> may store an operating system <NUM> utilized to control the operation of the computer <NUM>. According to one example, the operating system <NUM> comprises the LINUX operating system. According to another example, the operating system comprises the WINDOWS® SERVER operating system from MICROSOFT Corporation of Redmond, Washington. According to further examples, the operating system may comprise the UNIX operating system or one of its variants. It may be appreciated that other operating systems may also be utilized. The storage device <NUM> may store other system or application programs and data utilized by the computer <NUM>.

In one example, the storage device <NUM> or other computer-readable storage media is encoded with computer-executable instructions which, when loaded into the computer <NUM>, transform the computer from a general-purpose computing system into a special-purpose computer capable of implementing the examples described herein. These computer-executable instructions transform the computer <NUM> by specifying how the CPUs <NUM> transition between states, as described above. According to one example, the computer <NUM> has access to computer-readable storage media storing computer-executable instructions which, when executed by the computer <NUM>, perform the various processes described above with regard to <FIG>. The computer <NUM> may also include computer-readable storage media having instructions stored thereupon for performing any of the other computer-implemented operations described herein.

The computer <NUM> may also include one or more input/output controllers <NUM> for receiving and processing input from a number of input devices, such as a keyboard, a mouse, a touchpad, a touch screen, an electronic stylus, or other type of input device. Similarly, an input/output controller <NUM> may provide output to a display, such as a computer monitor, a flat-panel display, a digital projector, a printer, or other type of output device. It will be appreciated that the computer <NUM> might not include all of the components shown in <FIG>, may include other components that are not explicitly shown in <FIG>, or might utilize an architecture completely different than that shown in <FIG>.

As described herein, the computer <NUM> may comprise one or more of the central office <NUM>, the nodes <NUM> (e.g., utility meters), and/or other systems or devices associated with the central office <NUM>, the nodes <NUM> (e.g., utility meters) and/or remote from the central office <NUM>, the nodes <NUM> (e.g., utility meters). The computer <NUM> may include one or more hardware processor(s) such as the CPUs <NUM> configured to execute one or more stored instructions. The CPUs <NUM> may comprise one or more cores. Further, the computer <NUM> may include one or more network interfaces configured to provide communications between the computer <NUM> and other devices, such as the communications described herein as being performed by the central office <NUM>, the nodes <NUM> (e.g., utility meters), and other devices described herein. The network interfaces may include devices configured to couple to personal area networks (PANs), wired and wireless local area networks (LANs), wired and wireless wide area networks (WANs), and so forth. For example, the network interfaces may include devices compatible with Ethernet, Wi-Fi™, and so forth.

The programs <NUM> may comprise any type of programs or processes to perform the techniques described in this disclosure for a central office <NUM> and/or the nodes <NUM> (e.g., utility meters) as described herein. The programs <NUM> may enable the devices described herein to perform various operations.

In the examples described herein, a load-side voltage detection module for a metrology device may be used to identify instances where the disconnect switch of the metrology device may be closed safely without risk of the damage to the utility metering unit, devices and/or circuits associated with an alternative source of electrical power coupled to the load-side of the utility metering unit, the consumer's building, and other property described herein. Further, the examples described herein provide systems and methods to remotely disconnect and connect/reconnect the utility service (e.g., electrical power) provided via the utility metering unit without the need to dispatch a technician to the utility metering unit while maintaining the safety measures afforded by the load-side detection module.

While the present systems and methods are described with respect to the specific examples, it is to be understood that the scope of the present systems and methods are not limited to these specific examples. Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the present systems and methods are not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the scope of the present systems and methods.

Claim 1:
A load-side voltage detection module for a metrology device comprising:
a plurality of first resistors (<NUM>) electrically coupled to a first load-side terminal (<NUM>), the first resistors (<NUM>) being in series;
a plurality of second resistors (<NUM>) electrically coupled to a second load-side terminal (<NUM>), the second resistors (<NUM>) being in series and having resistance values different with respect to the first resistors (<NUM>);
a voltage divider (<NUM>) electrically coupled between a first line-side terminal and a second line-side terminal, the voltage divider (<NUM>) creating a reference voltage for the load-side voltage detection module; and
a pulse generator (<NUM>) to generate a pulse based on detection of voltage at at least one of the first load-side terminal (<NUM>) and the second load-side terminal (<NUM>), the pulse indicating a voltage on at least one of the first load-side terminal (<NUM>) or the second load-side terminal (<NUM>), above at least one threshold.