Background
[001] Technical Field
[002] The present invention generally relates to energy measurement, and more
specifically to an energy consumption alarm system/device.
[003] Related Art
[004] Energy consumption often needs to be measured to enable determination of the charges/tariff to be levied on the consumer for consumption of the energy. With respect to a device or system that consumes electrical energy, consumed energy is the product of the voltage applied to the device/system, the current drawn by the device/system, and the duration for which the device/system is operational (and draws electrical power).
[005] Energy meters (Watt-hour meters) are typically installed in consumer premises (e.g., house, factory) to measure energy consumption. The source of the energy may be a national or regional power grid or a standalone power plant (solar, fossil fuel, etc.). Typically, the energy consumption in a billing cycle (e.g., one month, quarterly, etc.) is recorded by an energy meter, for example, in terms of energy units (typically kilowatt hours), and the corresponding charges payable by the consumer are computed (either manually or in an automated fashion). However, there is a general need to provide a device/system that is additionally capable of generating alarms (e.g., to alert the consumer) based on energy usage. Such alarms may be designed with a view to enable cost savings, energy consumption planning, etc. to the consumer and/or producer of the energy.
Brief Description of Drawings [006] The present invention will be described with reference to the accompanying drawings, which are described briefly below. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. [007] Figure (Fig.) 1 is a block diagram illustrating a conventional (prior) energy measurement system.

[008] Figure 2 is a block diagram illustrating the details of an energy consumption
alarm system in an embodiment of the present invention.
[009] Figure 3 is a block diagram illustrating the details of a signal Measurement
and processing module in an embodiment of the present invention.
[0010] Figure 4 is a block diagram illustrating the details of a data acquisition and
processing module in an embodiment of the present invention.
[0011] Figure 5 is a block diagram illustrating the details of an output module in
an embodiment of the present invention.
[0012] Figure 6 is a block diagram illustrating the details of an alarm control
module in an embodiment of the present invention.
Detailed Description [0013] 1.Overview
[0014] A system for issuing energy consumption alarms includes an output device to generate an alarm and a processor. The processor is operable to compute electrical energy consumed by one or more appliances from a supply, and causes the output device to generate an alarm when a pre-determined condition with respect to the energy consumed is satisfied. The pre-determined condition can be when the energy consumed equals a pre-determined limit set by a user. [0015] Several aspects of the present invention will be clear by understanding the operation of some conventional prior systems, which do not implement one or more features of the present invention. Accordingly, one such example conventional system is described below first.
[0016] 2. Conventional System
[0017] Figure 1 is a block diagram illustrating the details of a conventional (prior) energy measurement system. Electrical supply 101 represents a power source that provides power for operation of one or more load devices (not shown). Signal measurement module 102 obtains instantaneous value of voltage level of electrical supply 101, and the current drawn by load device(s) from supply 101. Signal measurement module 102 may use current transformers for obtaining the current drawn from supply 101. The current and voltage values are provided in analog form to signal conditioning and memory module 102. Signal conditioning and

memory module 103 performs analog to digital conversion of the current and voltage values received in analog form. A processor contained in module 103 computes the energy consumed by multiplying current, voltage and the time for which current is drawn from supply 101. Instantaneous values (or values at every pre-defined interval, for example, every few milliseconds) of energy consumed (for example in terms of units such as Kilowatt-hour) are sent to output module 104, which displays the energy consumed on a display device contained in output module 104.
[0018] As may be appreciated, the prior energy measurement system merely computes the amount of energy consumed, and does not generate any alarms/alerts to alert the consumer regarding the energy consumed. [0019] Several aspects of the present disclosure are described below with reference to examples for illustration. However, one skilled in the relevant art will recognize that the disclosure can be practiced without one or more of the specific details or with other methods, components, materials and so forth. In other instances, well-known structures, materials, or operations are not shown in detail to avoid obscuring the features of the disclosure. Furthermore, the features/aspects described can be practiced in various combinations, though only some of the combinations are described herein for conciseness.
[0020] 3. Energy Consumption Alarm System
[0021] Figure 2 is a block diagram illustrating the details of an energy consumption alarm system in an embodiment of the present invention. The energy consumption alarm system not only computes the amount of energy consumed, but also generates alarms/ alerts to alert the consumer or the producer regarding the energy consumed. Electrical supply 201 shown in Figure 2 is same as supply 101 (of Figure 1), and is a source of electrical power (typically alternating current), such as for example, electrical mains provided at house, factories etc., and supplied by a national or regional power grid (230 Volts, 50 Hertz in India). Alternatively, supply 201 can correspond to a supply generated by a stand-alone power plant based on fossil fuel, solar energy, etc., also. One or more appliances (e.g., lights, machines, etc.) may be connected to supply 201 (although not

shown), and consume energy when operational. Energy consumption alarm system 200 is shown containing signal measurement and processing module 202, data acquisition and processing module 203, output module 204 and alarm module 205. Each module may be implemented as a corresponding card (on a printed circuit board/PCB), with appropriate connections between the cards. The details of each module and its operation are described below with reference to corresponding Figures.
[0022] 4. Signal Measurement and Processing Module
[0023] Figure 3 is a block diagram illustrating the details of Signal Measurement and Processing Module 202 in an embodiment of the present invention. Module 202 is shown containing voltage measurement block 301, current measurement block 303, voltage signal conditioning block 302, current signal conditioning block 304, and voltage regulator 305.
[0024] Voltage measurement block 301 receives supply 201, and contains circuits for generating a signal representing the voltage (e.g., 230 volts) of supply 201. In an embodiment, voltage measurement block 301 contains resistive and capacitive elements, and/or transformer for stepping-down voltage of supply 201 to a lower (standardized) reference value. Additionally, block 310 may also perform rectification of the stepped-down AC supply. Block 301 forwards the stepped-down voltage in analog form to voltage signal conditioning block 302. [0025] Voltage signal conditioning block 302 contains an analog to digital converter (ADC), and generates digital values representing the magnitude of the voltage received from block 301. The sampling rate, i.e., the number of voltage samples per second, may be pre-programmed to be a desired number, for example one sample every millisecond. Block 302 forwards the digital voltage values on path 209. Each voltage sample may be appended with a time stamp indicating the time instant at which the corresponding samples were generated, thereby enabling computation of energy consumption as a later step. The time stamps may be obtained from a time-keeping circuitry such as a real-time clock (RTC), not shown, but contained in system 200. The voltage values may be transmitted on path 209 according to a protocol convention, such as for example a serial protocol

(e.g., RS-232), or in general, consistent with the interface that receives the digital values transmitted on path 209.
[0026] Current measurement block 303 contains a current transformer that is magnetically coupled to the electrical supply 201 (e.g., phase wire of supply 201), and generates an output signal representing the magnitude of instantaneous current drawn from supply 201. Block 303 provides the output signal in analog form to current signal conditioning block 304.
[0027] Current signal conditioning block 304 contains an analog to digital converter (ADC), and generates digital values representing the magnitude of the current received from block 303. The sampling rate, i.e., the number of voltage samples per second, may be pre-programmed to be a desired number, for example, one sample every millisecond. In general, the sampling rate of the ADC contained in block 304 is the same as the sampling rate of the ADC of block 302. Further, the sampling instants of ADC of block 302 and the ADC of block 304 are synchronized such that respective voltage and current samples are obtained at the same time instant. Block 304 forwards the digital current values on path 210. Each current sample may be appended with a time stamp indicating the time instant at which the corresponding sample was generated. The current values may be transmitted on path 210 according to a protocol convention, such as for example a serial protocol (e.g., RS-232), or in general, consistent with the interface that receives the digital values transmitted on path 210.
[0028] Voltage regulator 305 receives supply 201 and performs voltage step down of the supply voltage to a smaller voltage, rectifies the stepped-down voltage, filters the rectified voltage, and operates to generate a regulated power supply from the rectified and filtered voltage. The regulated power supply is used for powering all the circuits/components/ICs in all the modules of system 200. Voltage regulator provides the regulated voltage on path 211.
[0029] 5. Data Acquisition and Processing Module
[0030] Figure 4 is a block diagram illustrating the details of Data Acquisition and Processing Module 203, in an embodiment of the present invention. Data acquisition and Processing Module 203 is shown containing Processor 402, Flash

Storage 403, Memory 404 and Signal, Input-Output and network interfaces (also termed interface blocks herein) 401-A and 401-B. Data acquisition and Processing Module 203 receives power for operation on path 211.
[0031] Each of interface blocks 401-A and 401-B is designed consistent with the interface requirements between processor 402 and external circuits/devices, and contains interface circuitry to enable processor 402 to communicate with external circuitry/devices. Merely as an example, each of blocks 401-A and 401-B can be a serial interface such as RS-232. However, interface blocks 401-A and 401-B are not limited to such serial interfaces, and any implementation suitable for enabling communication between processor 402 and external circuits/devices (i.e., external to module 203) can be used to implement these blocks.
[0032] Flash storage 403 represents a non-volatile memory (computer readable storage medium in general), which may be used to store instructions for execution by processor 402, as well as data. Memory 404 represents a volatile memory such as SRAM (Static Random Access Memory), and may be used to store temporary data. Processor 402 represents one or more processing units and executes instructions stored in the form of program code in flash storage 403. [0033] Interface block 401-A forwards the digital voltage and current samples received on paths 209 and 210 to processor 402. Processor 402 calculates the voltage of supply 201, and current drawn by one or more loads from supply 201, from the received voltage and current samples. In an embodiment, processor determines the voltage of supply 201, current drawn from supply 201, and the power-factor (phase angle between voltage and current of supply 201) every second (which may be viewed as a reference duration), based on multiple current and voltage samples received for that second. Processor 402 determines instantaneous power every second by multiplying the corresponding voltage, current and power-factor values determined for that second. Processor 402 computes energy consumption for a period of time by adding instantaneous power values for each 1-second interval in that period of time (T). For example, to determine energy consumed between 10AM and 11AM on a particular day, processor 402 adds all the instantaneous power values computed for each 1-

second interval between 10AM and 11AM for that day. In addition, processor 402 translates the energy consumption value thus computed to the number of units of energy consumed. For example, in India, one kilowatt-hour equals one unit of energy for the purposes of cost computation. Processor 402 converts the energy consumed (e.g., in Watt-hours) into the equivalent number of energy units. Various other techniques (different from the specific technique noted above) for computation of instantaneous power and energy consumed can also be used by processor 402, and is well-known in the relevant arts.
[0034] Processor 402 forwards the instantaneous power values determined for each second (along with the corresponding time instant details), as well as the present value of energy consumed (in terms of number of units, i.e., Kilowatt-hours), for storage in flash storage 403, and also to modules 204 and 205 via interface block 401-B. Processor 402 also computes the charges for the units of energy consumed, based on tariff data, slab rates, etc., pre-stored in flash storage 403, and also compares the computed charges to one or more limits specified by a user (as described below). Based on the comparison, processor 402 may issue an alert command to cause an alarm to be generated by alarm unit 603 as described below.
[0035] It is to be understood that processor 402 can be replaced by dedicated digital hardware units such as programmable logic devices, field programmable logic arrays (FPGA), etc., which can perform the same/similar operations performed by processor 402 as described above. In such an embodiment, the operation described herein is achieved not by virtue of execution of instructions by a processor, but instead hard-wired by the implementation of the dedicated digital hardware.
[0036] According to an aspect of the present invention, one or more alarms are generated by processor 402 when energy consumption approaches a pre-defined value set by a user. For example, a user of system 200 may provide as inputs to system 200 limits (for example, either in terms of energy units consumed or corresponding charges/tariff) , which when approached causes processor 402 to generate an alarm, as described below.

[0037] In an embodiment, the limits are the boundaries of rate slabs set by the energy supplying authority (e.g., electricity boards of various states in India). As is well known, the tariff for energy consumption may be set according to rate slabs. Thus, for example, one tariff rate (e.g., one rupee) may be set for energy consumption from 1 to 100 units, a next tariff rate (e.g., one rupee and fifty paise) may be set for energy consumption from 101 to 200 units, and so on. Thus, it may be appreciated that when energy consumption approaches 100 units (e.g., when energy consumed equals 90 units) for example, the consumer is benefited by being alerted to such condition, since a higher tariff rate is applicable for units greater than 100. Accordingly, the user may decide to switch off one or more or all appliances connected to supply 201, so that energy consumption does not exceed the number of units in the current slab (1-100). The user may resume energy consumption at a later time/date, for example when a next billing cycle (e.g., 1st of next month) commences, when the tariff computation starts again from the lowermost slab (1-100). Details of the tariff operation, such as tariff slabs (for one or more geographical areas, such as states) may either be pre-stored in flash storage 403, or provided by a user via input block 602 noted below. Operation of the embodiment is described further in sections below.
[0038] Processor 402 forwards each computed energy consumption value to interface block 401-B.
[0039] 6. Output Module
[0040] Figure 5 is a block diagram illustrating the details of output module 204 in an embodiment. Output module 204 is shown containing Signal, Input-Output and network interface (also termed interface block herein) 501, processor 502 and display 503. Output module 204 receives power for operation on path 211. [0041] Interface block 501 is designed consistent with the interface requirements between processor 502 and external circuits/devices via path 212, and contains interface circuitry to enable processor 502 to communicate with external circuitry/devices (for example in other modules). Interface block 501 may be designed/implemented similar to interface blocks 401-A and 401-B of module 203. Interface block 501 receives power and units of energy values in digital form

(computed by processor 402) from interface block 401-B, and forwards the power and energy values to processor 502.
[0042] Processor 502 operates as a display controller and is designed to interface directly with display 503, to drive display 503 to display information. Display 503 may be implemented, for example, as a Liquid Crystal Display card, or LED (light emitting diode) display, or any other available display technology, and displays information (e.g., text/graphics) received from processor 402 (via processor 502 and the corresponding interface blocks).
[0043] Thus, processor 502 receives data regarding instantaneous power as well as energy consumed from supply 201 (including number of units of energy consumed, time, date, charges for number of units of energy consumed), and forwards the data for display on display 503. Although, not shown, processor 402 can also forward the data noted above to external devices/systems, such as for example a computer terminal, and the computer terminal may in turn display the data on a monitor.
[0044] 7. Alarm Control Module
[0045] Figure 6 is a block diagram illustrating the details of alarm control module 205 in an embodiment of the present invention. Alarm control module 205 receives power for operation on path 211, and is shown containing signal, IO and network interface (interface block) 601, alarm unit 603 and input block 602. [0046] Interface block 601 provides the communication interface between input block 602 and external modules (e.g., interface block 401-B) connected to path 213, as well as between alarm unit 603 and external modules connected to path 213. Input block 602 enables inputs to be received from a user, and can be, for example a touchpad/keypad or voice-command module. Input block 602 forwards input data entered by a user to processor 402 via the corresponding interface blocks. Alarm unit 603 represents an output device, and can be implemented, for example, as a buzzer. Alarm unit 603 may additionally contain circuitry to receive commands from processor 402, and to generate corresponding audible sounds. Thus, processor 402 can cause alarm unit 603 to generate an audible warning

when energy consumption approaches or exceeds a corresponding limit (e.g., slab
boundaries).
[0047] Working of system 200 in an embodiment of the present invention is now
further described.
[0048] 8. Working of System
[0049] When system 200 is switched on, output module 204 displays a welcome note and a message prompting the user to enter the state (e.g., Tamil Nadu, Karnataka, etc.), or a geographical area subject to a corresponding energy tariff in general, in which system 100 is deployed. The user provides such information via input block 602, which forwards the information to processor 402 via the corresponding interface blocks, and thereafter stored by processor 402 in flash storage 403.
[0050] The user is then prompted to set an alarm either based either on the number of units of energy consumed (e.g., 90 or 100 units or equivalent kilowatt hours) or charges (e.g., in Rupees). Processor 402 operates to compute energy consumption as described above, and when the energy consumed reaches a limit (units or cost specified by user), processor 402 sends a command to cause alarm unit 603 to signal an audible alarm. In addition, processor 402 can also cause a corresponding ‘alert’ message to be displayed on display 503. For example, the user can cause system 200 to issue an audible alert/alarm whenever the energy consumed approaches a tariff slab boundary (e.g., 90 units assuming a slab boundary exists at 100 units). The user is also provided the feature of being able to reset system 200 (for example at end of a billing cycle, monthly, quarterly, etc.), so that energy consumption computation starts again from zero. [0051] A consumer is thus provided with the facility of being able to monitor his energy consumption, and to take preventive action to limit energy consumption if so desired.
[0052] 9. Conclusion
[0053] While various embodiments of the present invention have been described
above, it should be understood that they have been presented by way of example

only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments.

I/We Claim:
1. A system for issuing energy consumption alarms comprising:
an output device to generate an alarm; and
a processor to compute electrical energy consumed by one or more appliances from a supply, wherein said processor causes said output device to generate said alarm when a pre-determined condition with respect to said energy consumed is satisfied.
2. The system as claimed in claim 1, wherein said pre-determined condition
is satisfied when said energy consumed equals a pre-determined limit.
3. The system as claimed in claim 2, wherein said pre-determined limit is
provided to said processor as an input by a user, said system further comprising:
an input block to receive said pre-determined limit from said user, said input block to forward said pre-determined limit to said processor,
wherein said output device is a buzzer, said alarm being an audible sound.
4. The system as claimed in claim 3, wherein said pre-determined limit is
one of a value of units of said energy consumed and a charge for said units of energy
consumed.
5. The system as claimed in claim 4, wherein a tariff for said energy
consumed is in the form of different slabs, wherein said tariff for one slab is different
from a tariff for another slab.
6. The system as claimed in claim 3, further comprising:
a first circuit for sensing a voltage of said supply;
a second circuit for sensing a current drawn by one or more appliances from said supply;
a first analog to digital converter to generate a first set of digital samples representing said voltage at corresponding time instants;

a second analog to digital converter to generate a second set of digital samples representing said current at said corresponding time instants,
wherein said processor determines magnitudes of said voltage and said current in a reference duration, as well as a power factor value for said reference duration, by processing said first set of digital samples and first set of digital samples obtained for said reference duration,
wherein said processor determines a power consumed in said reference duration by multiplying said voltage, said current, and said power factor value,
wherein said processor determines energy consumed in a desired duration by summing power consumption values in said desired duration,
wherein said processor converts said energy consumed into an equivalent number of energy units.
7. A method of issuing energy consumption alarms by a system, said
method comprising:
computing, by a processor contained in said system, electrical energy consumed by one or more appliances from a supply;
determining, by said processor, whether a pre-determined condition with respect to said energy consumed is reached;
issuing, by said processor, a command when said pre-determined condition is satisfied; and
generating an alarm by an output device in said system in response to receipt of said command.
8. The method as claimed in claim 7, wherein said pre-determined
condition is when said energy consumed equals a pre-determined limit set by a user.
9. The method as claimed in claim 8, said pre-determined limit is one of a
value of units of said energy consumed and a charge for said units of energy
consumed.

10. The method as claimed in claim 9, further comprising:
sensing, by a first circuit in said system, a voltage of said supply;
sensing, by a second circuit in said system, a current drawn by one or more appliances from said supply;
generating, by a first analog to digital converter, a first set of digital samples representing said voltage at corresponding time instants;
generating, by a second analog to digital converter, a second set of digital samples representing said current at corresponding time instants,
wherein said computing determines magnitudes of said voltage and said current in a reference duration, as well as a power factor value for said reference duration, by processing said first set of digital samples and first set of digital samples obtained for said reference duration,
wherein said computing determines a power consumed in said reference duration by multiplying said voltage, said current, and said power factor value,
wherein said computing determines energy consumed in a desired duration by summing power consumption values in said desired duration,
wherein said computing converts said energy consumed into an equivalent number of energy units.