Controlling pulsed operation of a power supply during a power outage

A power supply control circuit for controlling operation of a power supply for an electricity meter during an alternating current (AC) power outage includes: an input section configured to receive a representation of an output voltage of the power supply and a power loss signal; a comparator section configured to generate an output signal based on the power loss signal and the representation of the output voltage; and a feedback control section configured to control a feedback signal to the power supply based on the output signal from the comparator section. When activated by the output signal from the comparator section, the feedback control section is configured to change the feedback signal with respect to the feedback signal from a feedback circuit caused the output voltage. The change in the feedback signal causes the power supply to stop supplying the output voltage.

BACKGROUND

An electricity meter measures electrical power consumed by a customer of an electric utility provider. The electricity meter is plugged into a meter socket that is mounted in an enclosure on a building or other structure, and draws its operating power from the electrical power distribution grid. Electricity meters record electric energy consumption and communicate the information as well as status information of the meter itself to the utility provider for monitoring and billing. When power outages occur, an electricity meter no longer has the ability to communicate with the utility provider.

In order to operate a radio to enable the electricity meter to provide a “last gasp” communication to the utility provider when a power outage occurs, electricity meters may rely on energy stored in storage capacitors to maintain operation of communication circuitry for a limited period of time. The stored energy needs to be sufficient to operate the electricity meter power supply to maintain radio operation. The capacitors needed to store sufficient energy to operate the radio for a long enough period of time can be large and expensive. Efficient power supply operation can maximize the time the radio can be operated on the limited energy available from the storage capacitors.

SUMMARY

Systems and methods for operation of an offline switching power supply for an electricity meter during a power outage may be provided.

According to various aspects there is provided a power supply control circuit for controlling operation of a power supply for an electricity meter during an alternating current (AC) power outage. In some aspects, the power supply control circuit may include: an input section configured to receive a representation of an output voltage of the power supply and a power loss signal; a comparator section configured to generate an output signal based on the power loss signal and the representation of the output voltage; and a feedback control section configured to control a feedback signal to the power supply based on the output signal from the comparator section. When activated by the output signal from the comparator section, the feedback control section may be configured to change the feedback signal with respect to the feedback signal generated by a feedback circuit based on the output voltage. The change in the feedback signal may cause the power supply to stop supplying the output voltage.

According to various aspects there is provided an electricity meter. In some aspects, the electricity meter may include: a power supply; and a power supply control circuit for controlling operation of the power supply for an electricity meter during an alternating current (AC) power outage. The power supply control circuit may include: an input section configured to receive a representation of an output voltage of the power supply and a power loss signal; a comparator section configured to generate an output signal based on the power loss signal and the representation of the output voltage; and a feedback control section configured to control a feedback signal to the power supply based on the output signal from the comparator section. When activated by the output signal from the comparator section, the feedback control configured to change the feedback signal with respect to the feedback signal generated by a feedback circuit based on the output voltage. The change in the feedback signal may cause the power supply to stop supplying the output voltage.

According to various aspects there is provided a method for controlling operation of a power supply for an electricity meter during an alternating current (AC) power outage. In some aspects, the method may include: receiving, by a power supply control circuit, an AC power loss signal; generating, by the power supply control circuit, a false feedback signal to the power supply, wherein the false feedback signal is different than a feedback signal generated by an output voltage of the power supply, wherein the false feedback signal causes the power supply to stop supplying the output voltage; determining that the output voltage of the power supply reached a lower voltage threshold; and in response to determining that the output voltage of the power supply reached the lower voltage threshold, ceasing generation of the false feedback signal.

DETAILED DESCRIPTION

While certain embodiments are described, these embodiments are presented by way of example only, and are not intended to limit the scope of protection. The apparatuses, methods, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the example methods and systems described herein may be made without departing from the scope of protection.

An electricity meter measures electrical power consumed by a customer of an electric utility provider. The electric electricity is plugged in to a meter socket that is mounted in an enclosure on a building or other structure and provides a connection between the electric power delivered by the electrical utility and the customer. The electricity meter measures and controls the electricity delivered to the customer premises via the grid. The electricity meter may be combined with a communications module to enable the meter to communicate with other meters and with the utility. The electricity meter may be part of a utility management system.

FIG.1is a diagram illustrating an example of a utility management system100according to various aspects of the present disclosure. Referring toFIG.1, the utility management system100may include an electricity meter105, a head-end system110, and a storage device120. WhileFIG.1illustrates one electricity meter105for ease of explanation, one of ordinary skill in the art will appreciate that a plurality of electricity meters105may be included in the disclosed utility management system100without departing from the scope of the present disclosure.

The electricity meter105may monitor and/or record the energy usage at the customer premises130and communicate the information about energy usage to the head-end system110. For example, the electricity meter105may continually monitor and record total energy usage at the customer premises130. In accordance with various aspects of the present disclosure, the electricity meter105may monitor and/or record days of the week and times of the day related to energy usage at the customer premises130and communicate the information to the head-end system110. In addition, the electricity meter105may perform as a sensor to detect and/or record abnormal measurements and/or events, for example, but not limited to, power outages. One of ordinary skill in the art will appreciate that other information, for example, but not limited to, average power consumed, peak power, etc., may be monitored and communicated by the electricity meter105.

The electricity meter105may communicate with the head-end system110via wired or wireless communication interfaces known to those of skill in the art using communication protocols appropriate to the specific communication interface. Different wired or wireless communication interfaces and associated communication protocols may be implemented on the electricity meter105for communication with the head-end system110. For example, in some embodiments a wired communication interface may be implemented, while in other embodiments a wireless communication interface may be implemented for communication between the electricity meter105and the head-end system110. In some embodiments, a wireless mesh network may connect a plurality of electricity meters105. The plurality of electricity meters105may transmit data to a collector (not shown) that communicates with another network to transmit the data to the head-end system110. The electricity meters105may use radio frequency (RF), cellular, or power line communication to communicate. One of ordinary skill in the art will appreciate that other communication methods may be used without departing from the scope of the present disclosure.

The head-end system110may include a storage device120. The storage device120may be, for example, but not limited to, one or more hard-disk drives, solid-state memory devices, or other computer-readable storage media. One of ordinary skill in the art will appreciate that other storage configurations may be used without departing from the scope of the present disclosure. A database125may be stored on the storage device120. The database125may store information collected from the electric meters105. For example, the database125may include days of the week and times of the day correlating with load is operating information, for example, but not limited to, average power consumed by the load, peak power consumed by the load, etc. One of ordinary skill in the art will appreciate that this information is exemplary and that other information may be included in the database125without departing from the scope of the present disclosure.

The head-end system110and the electricity meter105may be connected to an electrical power distribution grid140. The electrical power distribution grid140may include generating stations (not shown) that produce electric power (not shown), electrical substations (not shown) for stepping electrical voltage up for transmission or stepping electrical voltage down for distribution, high voltage transmission lines (not shown), and distribution lines (not shown).

FIG.2is a simplified block diagram illustrating an example of an electricity meter200according to some aspects of the present disclosure. The electricity meter200may be, for example, the electricity meter105ofFIG.1. The electricity meter200may also be referred to as a smart meter or a smart electricity meter. The electricity meter200may include a control circuit205, a memory220, a communications module230, various sensors240, a power supply260, and one or more storage capacitors270.

The control circuit205may include a processor210, a memory220, measurement circuitry250, and a power supply control circuit265. The processor210may be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device. The processor210may be in electrical communication with the memory220, the communications module230, and the sensors240. The processor210may control overall operation of the electricity meter200. The processor210may receive data generated by various sensors240of the electricity meter200including, but not limited to, energy use, voltage, current, etc., and may perform operations on, or processing of, the data. The processor210may communicate with the communications module230to transmit various operational parameters (e.g., energy usage), diagnostic data (e.g., error conditions), or other electric meter information (e.g., GPS coordinates) to a head-end system and/or to other electric meters via a wired or wireless network.

The memory220may be a storage device such as a solid state storage device or other storage device, and may be a combination of volatile and non-volatile storage or memory. In some implementations, portions of the memory may be included in the processor210. The memory220may be configured to store instructions executable by the processor210, as well as data generated by the various sensors240of the electricity meter200, and other applications executable by the processor210.

The communications module230may be a wired or wireless transceiver operable to communicate via various wired or wireless protocols as known in the field for example, but not limited to, the AMI protocol, RF protocols, cellular protocols, PLC network protocols, etc. The communications module230may include a processor235configured to control operation of the communications module230. In some implementations, the communications module230may include AMI devices and/or AMR devices, including an AMI radio and/or an AMR radio237. The AMI radio and/or AMR radio237may transmit data to and receive data from the head-end system using radio frequency (RF) technologies or power line communication (PLC). The communications module230may enable the electricity meter200to communicate with other electricity meters in a network (e.g., an AMI network) and with the utility provider (e.g., a head-end system). The communications module230may transmit data and alarm signals to the utility provider and receive any of updated program instructions, firmware updates, updates to other settings, or other communications.

The sensors240may include, but are not limited to, voltage sensors, current sensors, accelerometers, tilt switches, temperature sensors, and other sensors configured to monitor electrical and physical characteristics of the electricity meter200.

The measurement circuitry250may interface with the sensors240. The measurement circuitry250may include an analog-to-digital (A/D) converter256configured to receive analog signals from the sensors240and convert the analog signals to digital values that may be operated on by the processor210.

The power supply260may be a direct current (DC) power supply and may receive a primary DC voltage generated by rectifying a primary alternating current (AC) voltage from the grid to which the electricity meter200is connected. The power supply260may also be referred to herein as an offline switching power supply or an offline power supply. In some implementations, power supply260may receive and rectify the primary AC voltage. The power supply260may generate a lower secondary voltage DC from the primary DC voltage. The secondary DC voltage generated by the power supply260may supply DC power to other components of the electricity meter200.

The power supply control circuit265may control the amount of time the power supply260can operate at its operational switching frequency during a loss of primary AC voltage from the grid. The power supply control circuit265may receive an AC power loss signal and may cause the power supply260to operate only after the secondary DC voltage decreases to a specified lower threshold value and may cause the power supply260to cease operation when the secondary DC voltage increases to a specified upper voltage threshold. The power supply control circuit265may cause the on-off duty cycle of the power supply260to continue as the secondary DC voltage reaches the lower and upper threshold values until the energy stored in the primary holdup capacitors270is depleted.

The electricity meter200may further include one or more regulated power supplies262. The regulated power supplies262may receive the secondary DC voltage output from the power supply260and may regulate the secondary DC voltage to lower DC voltages for operating other circuitry of the electricity meter200, for example, but not limited to, the AMI radio and/or AMR radio237.

The storage capacitors270may provide primary power to the electricity meter200for a short period of time immediately after a power outage. The storage capacitors270may be electric double layer capacitors (EDLC), also referred to as an ultracapacitors or supercapacitors, or another type of capacitor. The storage capacitors270may store sufficient energy to operate the power supply260for a limited period of time to enable the electricity meter200to transmit a “last gasp” message to the head-end system. The last gasp message may include a notification of the power outage as well as other information (e.g., energy usage, error conditions, or other electric meter information) at the time power was lost.

While offline switching power supplies can alter their operation to increase their efficiency while supplying power to low loads, operation can still be lossy with low efficiencies (e.g., less than 50%). The default low load control mechanisms of offline switching power supplies maintain good regulation on the output, and therefore operate switching cycles at frequencies in the kHz range to maintain the regulation.

According to some aspects of the present disclosure, the operational time for the electricity meter to transmit a “last gasp” message may be extended by pulsed operation of the offline switching power supply. The pulsed operation may be achieved by overriding a feedback signal to the offline switching power supply, thereby extending the off time of the on-off periodic operation of the offline switching power supply for a longer than typical duration. When the offline switching power supply is turned back on, it may operate at near full load which is higher on the power supply efficiency curve.

While the extended off time can introduce a large ripple on the secondary voltage, the increased ripple can be acceptable for some applications such as providing power for the electricity meter during a power outage. The pulsed operation of the offline switcher can allow higher efficiency switching cycles to be used which translates into higher energy transfer from primary to secondary of the power supply. The higher energy transfer can result in longer holdup times for the secondary voltages of the electricity meter during a power outage. Under expected use case applications in an electricity meter, an approximately 7.5% increase in the holdup time may be provided.

FIG.3is a simplified block diagram illustrating an example of an electric meter300including a power supply control circuit365according to some aspects of the present disclosure. Referring toFIG.3, the electricity meter300may include an offline switching power supply310, a first regulated power supply320, a second regulated power supply325, and control circuit305. The control circuit305may be, for example, the control circuit205inFIG.2. The power supply control circuit365may be part of the control circuit305or may be circuitry separate from the control circuit. The power supply control circuit365may be, for example, the power supply control circuit265inFIG.2. The offline switching power supply310may operate with an input voltage from a primary DC voltage of the electricity meter300. The primary DC voltage may be a generated from an AC line voltage rectified by a full wave rectifier302. The primary DC voltage may be, for example, 350 volts DC (VDC) or another DC voltage. The offline switching power supply310may supply a secondary DC voltage Vsec to the first regulated power supply320and the second regulated power supply325.

The offline switching power supply310may be a switching power supply, for example, but not limited to a buck-boost power supply or other power supply, operable to convert the primary DC voltage into a lower secondary DC voltage Vsec. The secondary DC voltage Vsec may be for example, 12 VDC or another DC voltage. The offline switching power supply310may convert the primary DC voltage to the secondary DC voltage Vsec by periodically transferring energy stored in the primary winding of the coupled inductor315to the secondary winding of the coupled inductor315. Electrical isolation (e.g., galvanic isolation) between circuitry connected to the primary DC voltage and circuitry connected to the secondary DC voltage may be provided by the coupled inductor315. In some implementations, the coupled inductor315may be a transformer. Isolated feedback of the secondary DC voltage Vsec may be provided to the offline switching power supply310via an isolation device312, for example, but not limited to, an opto-coupler or other isolation device.

The first regulated power supply320may be a switching power supply or other power supply operable to convert the secondary DC voltage Vsec provided by the offline switching power supply310to a lower voltage, for example 3.6 VDC or another DC voltage. The first regulated power supply320may supply power for components of the electricity meter300, for example, but not limited to, the AMI radio and/or AMR radio330.

The second regulated power supply325may be a switching power supply or other power supply operable to convert the secondary DC voltage Vsec provided by the offline switching power supply310to a lower voltage, for example 3.3 VDC or another DC voltage. The second regulated power supply325may supply power for auxiliary circuitry and/or components that are not required to be operated during an AC power outage. The auxiliary circuitry340and/or components may be switched off during an AC power outage.

When an AC power outage occurs, the power supply control circuit365may receive an AC power loss signal352from AC power loss detection circuitry (not shown) indicating the loss of AC power. The power supply control circuit365may operate to provide a false feedback signal354to the offline switching power supply310via the isolation device312. The false feedback signal354may provide an indication to the offline switching power supply310that the secondary DC voltage Vsec is higher than the actual secondary DC voltage Vsec. Providing a false feedback signal indicating that the secondary DC voltage Vsec is higher than the actual secondary DC voltage Vsec can cause the offline switching power supply310to remain in an off state (e.g., no switching) for longer periods of time.

When the secondary DC voltage Vsec reaches a specified lower threshold value, the power supply control circuit365may provide the actual feedback signal (e.g., the feedback signal generated by the actual secondary DC voltage Vsec) to the offline switching power supply310. The lower threshold value may be a minimum voltage needed to operate specified components of the electric meter, for example, but not limited to, the AMI/AMR radio or other components. The actual feedback signal may provide an indication to the offline switching power supply310that the secondary DC voltage Vsec is below the regulation point, thereby causing the offline switching power supply310to begin operating at its full operational frequency duty cycle in an attempt to quickly reach its normal regulated secondary DC voltage Vsec output. In some implementations, the offline switching power supply may operate with a fixed duty cycle and variable switching frequency. In such implementations, the offline switching power supply may increase its switching frequency to attempt to reach its normal regulated secondary DC voltage Vsec output.

When the secondary DC voltage Vsec reaches a specified upper threshold value, the power supply control circuit365may again operate to provide a false feedback signal354to the offline switching power supply310. The specified upper threshold value may be set lower than the normal regulated secondary DC voltage. The false feedback signal354may provide an indication that the secondary DC voltage Vsec is higher than the actual secondary DC voltage Vsec, thereby causing the offline switching power supply310to turn off (e.g., stop switching). The power supply control circuit365may cause the on-off duty cycle of the offline switching power supply310to continue as the secondary DC voltage reaches the lower and upper voltage thresholds until the energy stored in the primary holdup capacitors370is depleted.

FIG.4is a simplified schematic diagram illustrating an example of a power supply control circuit400according to some aspect of the present disclosure. The power supply control circuit400may be, for example, the power supply control circuit365inFIG.3. Referring toFIG.4, the power supply control circuit365may include an input section401, a comparator section402, and a feedback control section403.

The input section401may include components that function to monitor AC power loss352and the output voltage Vsec404, and provide an input signal to the comparator section402For example, application of the output voltage Vsec404to the comparator section may be controlled by a first switching device405and a second switching device410may monitor for AC power loss352. The switching devices may be, for example, transistors such as MOSFETS, bipolar transistors, or other transistor types. In some implementations, the functions of the input section401may be provided by analog circuitry such as operational amplifiers, or by a processor configured to monitor for AC power loss and control the output voltage, or via logic gates controlled by a processor.

The comparator section402may include a comparator420and feedback components. The comparator may be, for example, but not limited to, an operational amplifier, a processor, logic gates, etc. The feedback control section403may include a third switching device415.

During normal operation of the electricity meter, a feedback circuit450senses the output voltage Vsec404and provides a sense signal452to the isolation device312. The sense signal452causes the isolation device312to generate a feedback signal354to the offline switching power supply310. The feedback signal354enables the offline switching power supply310to regulate the output voltage Vsec404to a specified voltage, for example, 12 VDC or another DC voltage.

The output voltage Vsec404of the offline switching power supply310may be applied to the first switching device405. In some implementations, a representation of the output voltage Vsec404may be applied to the first switching device405. For example, the representation may be a scaled output voltage of a voltage divider or other voltage dependent on the output voltage Vsec404may be applied to the first switching device405. The first switching device405may be, for example, a p-channel MOSFET or another switching device. When a loss of AC power is detected, power loss detection circuitry (not shown) may generate an AC power loss signal352to the second switching device410. The second switching device410may be, for example, an n-channel MOSFET or another switching device.

When the AC power loss signal352is received, the second switching device410may cause the first switching device405to provide the output voltage Vsec404of the offline switching power supply310or the representation of the output voltage Vsec404to a first input422(e.g., the positive input) of the comparator420. A reference voltage406may be applied to a second input424(e.g., the negative input) of the comparator420. The reference voltage406may be, for example, an operating voltage for a specified component, for example, the AMI/AMR radio330, or other portion of circuitry of the electricity meter. The reference voltage406may be a voltage generated by regulating the output voltage Vsec404of the offline switching power supply310to a lower voltage, for example, 3.6 VDC or another voltage. In some implementations, a representation of the reference voltage406may be applied to the to a second input424of the comparator420. For example, the representation may be a scaled output voltage of a voltage divider or other voltage dependent on the operating voltage for the specified component may be applied to the second input424of the comparator420.

With the output voltage Vsec404or the representation of the output voltage Vsec404applied to the first input422of the comparator420just after the AC power loss signal352signal is received, the output signal of the comparator420may change the feedback signal. For example, the output signal of the comparator420may be in a high state, thereby causing the third switching device415to conduct current. The third switching device415may be, for example, an n-channel MOSFET or another switching device. The current conducted through the third switching device415is drawn through the isolation device312, thereby causing the isolation device312to generate a higher feedback signal354(e.g., a false feedback signal) than generated from the sense signal452provided by the feedback circuit450based on the output voltage Vsec404. The higher feedback signal354may cause the offline switching power supply310to remain in an off state (e.g., no switching) even though the actual output voltage Vsec404decreases below the specified regulation point for the output voltage Vsec404. In some implementations, the operation of the comparator420may cause the feedback signal to decrease.

After a period of time, the output voltage Vsec404may decrease to a specified lower threshold value, for example, 4 VDC or another DC voltage, since the offline switching power supply310is in an off state. The lower threshold value may be higher than a minimum voltage needed to operate a specified component of the electric meter, for example, but not limited to the AMI/AMR radio or other component. When the output voltage Vsec404decreases to the specified lower threshold value, the output signal of the comparator420may change to a low state, thereby causing the third switching device415to cease conducting current. The sense signal452provided by the feedback circuit450may cause the isolation device312to generate a feedback signal354based on the actual output voltage Vsec404. Since the actual output voltage Vsec404may be much lower (e.g., 4 VDC) than the specified regulation point for the output voltage Vsec404, the feedback signal354may cause the offline switching power supply310to turn on at substantially its full operational switching frequency duty cycle to bring the output voltage Vsec404into regulation.

As the output voltage Vsec404increases toward the specified regulation point (e.g., 12 VDC) an upper threshold value may be reached. The upper threshold value may be lower than the specified regulation point, for example 10 VDC or another voltage. In some implementations, the upper threshold value may be may be a scaled representation of the specified regulation point. For example, the representation may be a scaled output voltage of a voltage divider or other voltage dependent on the specified regulation point. When the output voltage Vsec404reaches the upper threshold value, the output signal of the comparator420may again change from a low state to a high state, thereby causing the third switching device415to conduct current. The output signal of the comparator in the high state may be proportional to the output voltage Vsec404and may decrease along with the decreasing output voltage Vsec404. The current conducted by the third switching device415may cause the isolation device312to generate the false (e.g., higher or lower) feedback signal354which may cause the offline switching power supply310to go to an off state (e.g., no switching) even though the output voltage Vsec404is below the specified regulation point.

The power supply control circuit400may cause the on-off duty cycle of the offline switching power supply310to continue as the output voltage Vsec404reaches the lower and upper thresholds until the energy stored in the primary holdup capacitors370is depleted. The upper and lower voltage thresholds that cause the comparator420to change state may be set by appropriate selection of feedback components in the comparator section402to provide hysteresis for the comparator420as known to those skilled in the art.

FIG.5is a flowchart illustrating an example of a method500for operation of an offline switching power supply for an electricity meter during a power outage according to aspects of the present disclosure. Referring toFIG.5, at block510, an AC power loss signal may be received. Duty cycle control circuitry, for example, the power supply control circuit400, may receive an AC power loss signal from AC power loss detection circuitry indicating the loss of AC power to the electricity meter.

At block520, a false feedback signal may be generated. When the AC power loss signal is received, the power supply control circuit may generate a false (e.g., higher or lower) feedback signal to the offline switching power supply (e.g., the offline switching power supply310). The false feedback signal may provide an indication to the offline switching power supply that the output voltage of the offline switching power supply is higher than the actual output voltage. The false feedback signal can cause the offline switching power supply to remain in an off state (e.g., no switching) for longer periods of time.

At block530, it may be determined whether the output voltage reached a lower threshold value. The lower threshold value may be a voltage higher than a minimum voltage needed to operate a specified component of the electric meter, for example, but not limited to the AMI/AMR radio or other component. In response to determining that the output voltage has not reached the lower threshold value (530-N), the false feedback signal may continue being generated at block520.

In response to determining that the output voltage has reached the lower threshold value (530-Y), at block540, the false feedback signal may cease being generated. The power supply control circuit may stop generating the false (e.g., higher or lower) feedback signal to the offline switching power supply, and the actual feedback signal may be generated by a feedback circuit of the electricity meter. The feedback circuit senses the output voltage and provides a sense signal to an isolation device that causes the isolation device to generate a feedback signal to the offline switching power supply based on the actual output voltage. The feedback signal enables the offline switching power supply to regulate the output voltage404to a specified voltage, for example, 12 VDC.

At block550, it may be determined whether the output voltage reached to an upper threshold value. As the output voltage Vsec404increases toward the specified regulation point for the output voltage (e.g., 12 VDC) an upper threshold value may be reached. The upper threshold value may be lower than the specified regulation point, for example 10 VDC or another voltage. In some implementations, In some implementations, the upper threshold value may be may be a scaled representation of the specified regulation point. In response to determining that the output voltage is not greater than or equal to the upper threshold value (550-N), the actual feedback signal, rather than the false feedback signal, may continue to be generated at block540.

In response to determining that the output voltage has not reached the upper threshold value (550-Y), the false feedback signal may again be generated at block520. The power supply control circuit may cause the on-off duty cycle of the offline switching power supply to continue as the output voltage reaches the lower and upper voltage thresholds until the energy stored in the primary holdup capacitors is depleted.

The specific operations illustrated inFIG.5provide a particular method for operation of an offline switching power supply for an electricity meter during a power outage according to an embodiment of the present disclosure. Other sequences of operations may also be performed according to alternative embodiments. For example, alternative embodiments of the present disclosure may perform the operations outlined above in a different order. Moreover, the individual operations illustrated inFIG.5may include multiple sub-operations that may be performed in various sequences as appropriate to the individual operation. Furthermore, additional operations may be added or removed depending on the particular applications.

The method500, may be embodied on a non-transitory computer readable medium, for example, but not limited to, the memory220or other non-transitory computer readable medium known to those of skill in the art, having stored therein a program including computer executable instructions for making a processor, computer, or other programmable device execute the operations of the methods.

The examples and embodiments described herein are for illustrative purposes only. Various modifications or changes in light thereof will be apparent to persons skilled in the art. These are to be included within the spirit and purview of this application, and the scope of the appended claims, which follow.