FIELD OF INVENTION
[001] The present invention relates in general to energy meters. The 5 present invention more particularly relates to a compact din-rail mountable current limiter with pre-paid multiple source energy meter.
BACKGROUND/PRIOR ART
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[002] Currently, consumers opt for multiple power sources to ensure un-interrupted power. Power is used from mains/utility, diesel, solar generators, wind powered sources, battery etc. Hence electricity meters are also required for multiple sources.
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[003] Separate energy meters are known to have been provided for multiple power supplies which creates a complex wiring system. However, the system is bulky, therefore occupies more installation space. Overloading issues are often faced as the extra current drawn from the system by consumer is dangerous for these supply systems as 20 well as for consumer. It also puts a lot of pressure on the auxiliary power source as multiple users draw power from same auxiliary source. Often builders have to install current limiters for these sources in addition to energy meter. It further compounds the problem of wiring complexity and utilization of space. 25
[004] Also in post-paid meters, as there is no restriction, so consumers often receive large bills due to brake free electricity consumption.
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[005] The few prior-art devices which perform such functions have a huge size and non-standard mounting. Hence, they cannot be mounted in standard power boards/ mounting boards/ MCB distribution boards. As they are not mountable on standard din-rails, a customized solution 5 is needed for every application which is inconvenient. It also consumes more time of electrician during installation and maintenance.
[006] A big size is also a disadvantage as space is crucial factor in modern housing societies where generally multiple consumer’s energy 10 meters are installed together in a compound or lobby.
[007] In view of the above, there is a requirement to devise a compact meter without compromising on its functional capabilities.
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[008] Publication No. US6097182 (A) discloses an electronic energy meter for use with a 3-wire delta service having a resistive voltage divider for sensing and scaling the line voltages. The resistive voltage divider includes three resistive dividers, one being associated with each phase of the electrical energy being metered. Each resistive divider 20 includes a current limiter for reducing the current into the meter to a safe level when the meter electronics are operating at an elevated level, and a resistor for scaling the line voltage to a predetermined maximum peak-to-peak value.
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[009] The aim of this invention is energy metering for a wide range of voltages with a single meter. It is neither pre-paid nor a multi-source meter. Further, it also does not have load limiting functionality, i.e.
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when current drawn from mains/auxiliary sources exceeds a threshold value, the circuit gets disconnected.
[0010] Publication No. CN203445786 (U) is directed to a three-phase electric energy meter and provides a low power consumption high 5 precision three-phase power supply module with overload protection used in a three-phase electric energy meter with a zero line judgment function. The three-phase power supply module comprises a rectifying circuit, a set-down circuit, a zero line judging circuit, a high-frequency filtering circuit, a switch power supply circuit, a rectifying and voltage 10 stabilizing circuit and an overcurrent protection circuit.
[0011] It is not a multi-source energy meter with pre-paid recharging facility. Further they have described about a circuit for zero line judgement and overload protection specific to power supply module. 15
[0012] Publication No. CN203445603 (U) makes a disclosure regarding a three-phase electric energy meter with overload protection. The three-phase power module comprises a rectifying and filtering circuit, a set-down circuit, a switch power supply circuit, a rectifying and voltage 20 stabilizing circuit and an overload protection circuit which are connected orderly.
[0013] This is directed to an overload protection circuit for power supply unit. 25
[0014] Publication No. CN203720260 (U) is related to an electric energy meter having a power protection circuit. The meter comprises an
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electric energy meter body and a communication module and is characterized by further comprising the power protection circuit. The input terminal of the power protection circuit is connected with the electric energy meter body, while the output terminal of the power protection circuit is connected with the communication module. The 5 power protection circuit comprises a current sampling circuit unit, a voltage comparison circuit unit, and an on-off control circuit unit. The current sampling circuit unit and the voltage comparison circuit unit are connected electrically.
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[0015] The above discusses about a circuit for operating the power supply unit during overload/ short-circuit.
[0016] Publication No. CN2709984 (Y) provides a protection switch of electric energy meter, comprising a spliced box body. A movable contact 15 arranged inside the box body is electrically connected with an overload protection assembly by a conductive band. The inner part of a wire inlet of the box body is provided with a platy terminal and a cable clamp which is used for clamping external cables. One lateral wall of the box body is provided with a wire outlet, and the inner part of the wire outlet 20 is provided with a connecting terminal which is electrically connected with the overload protection assembly. The protection switch of electric energy meter of the utility model can be installed inside an electric energy meter and form an entirety with the electric energy meter, in order to avoid the complicated operation of the electric energy meter and 25 a protection switch of the electric energy meter which are mounted separately, and reduce the mounting space being occupied.
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[0017] The given invention proposes an electric meter with meter protection switch and overload protection assembly comprising over-voltage protection coil, bimetal, fixed and moving contacts, mechanical switch assembly etc. with no relay based auto overload cut-off facility.
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[0018] Further their invention does not discuss about pre-paid and multi-source compact energy meter with no communication port etc.
[0019] Publication No. CN2909270 (Y) discloses an electric energy meter, in particular to an overload protection energy meter, including a circuit 10 breaker and an energy meter. The circuit breaker is fixed on the soleplate of the energy meter and is positioned below the energy meter instrument and the circuit breaker is connected with the output circuit of the meter.
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[0020] The given invention proposes to use an energy meter with a circuit-breaker attached to it in a defined arrangement. Further it is not a pre-paid and multi-source energy meter with relay based over-load cut-off facility.
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[0021] Publication No. CN202256422 (U) discloses a modularized intelligent electric energy meter, comprising a microcontroller, a storage module, a display module, an overload protection module, a clock 25 module, a power supply processing module, a load identification electric energy metering module, a carrier wave module and a relay control module which are integrated on a system chip, wherein the storage
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module, the display module, the overload protection module, the clock module, the power supply processing module, the load identification electric energy metering module, the carrier wave module and the relay control module are all connected with the microcontroller one end of each one of the overload protection module, the power supply processing 5 module, the load identification electric energy metering module and the carrier wave module is connected with a live line, while the other end of each one of the overload protection module, the power supply processing module, the load identification electric energy metering module and the carrier wave module is connected with a null line. 10
[0022] This invention does not discuss about multi-source energy metering with no pre-paid energy meter. It does not focus on the compact size and assembly of such a multi-functional energy meter.
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[0023] Publication No. CN202693644 (U) is directed to a novel remote monitoring integrated meter reading box. The novel remote monitoring integrated meter reading box comprises a multifunctional electric energy meter module, and further comprises an electric leakage protector, an LCD panel, a wireless communication module, an electric meter 20 acquisition RS485 interface, and an infrared/RS232 interface which are connected with the multifunctional electric energy meter module. The electric leakage protector is used for cutting off the power supply in overload and electric leakage. The LCD panel is used for the data display of a multifunctional electric energy meter. The wireless communication 25 module is used for sending abnormal data information and real-time electric meter data information of the multifunctional electric energy meter to a user. The RS485 interface is used for bus acquisition of user
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field electric meter data, and transmits the user field electric meter data to a power supply department base station. The infrared/RS232 interface is used for carrying out system software upgrading on the multifunctional electric energy meter.
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[0024] The proposed invention talks about an integration module with energy meters which can be used for leakage protection, wireless communication etc. It does not mention about din-rail mountable, compact or pre-paid energy meter nor it is designed for multiple energy sources. It also does not use relay based current limiting for multiple 10 power sources.
[0025] Publication No. CN202748872 (U) discloses a prepayment electric energy meter. The prepayment electric energy meter comprises a central control module, a display module, a charging module, a remote 15 communication module and an electric energy monitoring module, wherein the display module, the charging module, the remote communication module and the electric energy are respectively connected with the central control module. The prepayment electric energy meter is characterized in that the central control module is 20 respectively connected with an electricity stealing monitoring module and an overload monitoring module. The electricity stealing monitoring module is arranged, so that the electric energy meter can timely find an electricity stealing behavior and timely notifies the electric power company of the condition by the remote communicating module. The 25 overload monitoring module is used, so that the overload monitoring module sends a special signal to the central control module when the current of the electric energy meter continuously exceeds safety limit
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current for 10 seconds, so that the central control module controls the electric energy meter to complete a turn-off operation.
[0026] The given invention is not a multi-source energy meter. Further it does not talk about compact size, design and assembly of din-5 rail mountable pre-paid energy meter with relay based overload cut-off facility.
[0027] Publication No. CN202794333 (U) discloses a wind power electric energy meter based on DSP and ARM. The electric energy 10 meter comprises a mutual inductance unit composed of a current transformer and a voltage transformer; a difference amplifier connected with the mutual inductance unit; an anti-aliasing filter connected with the difference amplifier; a phase lock frequency multiplying unit and an A/D converter both connected with the anti-aliasing filter. A DSP 15 processor connected with the A/D converter; a FLASH, an SRAM, a serial port expander and an ARM processor all are connected with the DSP processor; a data memory, a short message alarm, a display and man-machine interface and an Ethernet interface connected with the ARM processor; and a CPLD logic controller cooperating with the phase 20 lock frequency multiplying unit, the A/D converter, the FLASH, the SRAM, the serial port expander and the DSP processor.
[0028] The given invention discloses a specific wind power energy meter based on DSP and ARM. It is not related to the compact size and 25 assembly of a prepaid multi-source energy meter with over-load cutoff facility.
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[0029] Publication No. CN205375815 (U) discloses a wisdom energy modularization monitoring system based on smart electric meter, including smart electric meter, wherein the smart electric meter input is connected with current transformer, gas flow signal end and liquid flow signal end. Smart electric meter has data 5 acquisition module through RS485 interface connection, data acquisition module passes through the ethernet and connects the energy monitoring module of enterprise, and data acquisition module still is connected with the data upload module. The data upload module is passed through the ethernet and is connected to the outer net 10 with the energy management platform module of data upload to appointed address.
[0030] The given invention proposes an electricity meter for smart grids for gas, liquid metering in addition to electricity metering. 15
[0031] Indian Publication No. 153/MUM/2012 discloses a data fetching system adapted for remotely fetching the data from a DIN mountable energy meter. The data fetching system comprises a DIN mountable Wi-Fi module adapted to communicate with the DIN mountable energy 20 meter through a first communication medium. The data fetching system includes a handheld data receiving device communicating with the DIN
mountable Wi-Fi module through a second communication medium. The data fetching system includes a plurality of screens on the handheld 25 data receiving device presented by a customized application loaded on the handheld data receiving device.
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[0032] It is not pre-paid nor does a multiple source energy meter, nor it have overload cut-off protection. It is not linked to the compact size and assembly of a multi-functional meter.
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[0033] Thus, none of the above can fulfill the requirements of the present invention for which it is designed.
[0034] In view of the above, there is a need of a simplified energy metering and current limiting solution, for multi-sources, which is 10 compact, easy to install and use.
[0035] Hence the present invention has been introduced to provide a compact din mountable current limiter with pre-paid energy meter for multiple sources. 15
OBJECTS OF THE INVENTION
[0036] The principal objective of the present invention is to provide a compact din-rail mountable current limiter with pre-paid energy meter 20 for multiple sources.
[0037] Another object of the present invention is to provide a light weight single unit which provides energy metering as well as current limiting of multiple power sources in compact size to save installation space. 25
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[0038] Yet another object of the present invention is to provide a smart multi-functional energy metering device having variable mounting options to impart flexibility and to reduce installation time and efforts.
[0039] Still another objective of the present invention is to provide a 5 compact energy meter with current limiter such that it can be installed in MCB distribution boards.
[0040] Further object of the present invention is to reduce wiring complexity. 10
[0041] Still further object of the present invention is to provide a smart energy metering device having means to communicate with user.
SUMMARY OF THE INVENTION 15
According to this invention, there is provided a compact din-rail mountable current limiter with pre-paid multiple source energy meter comprising main controller and energy metering unit, current limiting unit, power supply unit and communication unit provided in 20 connection, atleast one of which has individual electronic circuit board and a multiple layered structure to obtain compact device.
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[0042] A plurality of ports are provided for connecting different devices in series, which can be further connected to a central data consolidator unit and another port is provided for to and fro data exchange with
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user display, in which incoming and outgoing power terminals are provided at bottom side of the device.
[0043] The incoming phase terminals are connected to respective incoming copper bar passing through respective toroidal core current 5 transformer.
[0044] The main controller unit senses the current in each of said phases and signals to the current limiting unit, which actuates a relay to cut-off the particular phase in case of occurance of over-loading on 10 any of the phases.
[0045] The outgoing phase copper bars connect relay output to outgoing terminals, in which the incoming and outgoing neutral terminals are shorted via a copper bar. 15
[0046] The main controller and energy metering unit is placed above the CTs and incoming/outgoing copper bars, in which the current limiting unit is positioned above relays, adjacent to the main controller unit. 20
[0047] The four layered main controller and energy metering unit senses various parameters such as real-time power consumption (active power/apparent power/reactive power), voltage, current, frequency, power factor, kWh units till date, the source which is running 25 currently, remaining rupee balance etc. In addition to the above, there is provision of a display to indicate date, time, electrical
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parameters, running source and leftover prepaid balance; and a scroll button, an IRDA port and an indicator on the main unit.
[0048] The power supply unit is located in parallel to the side wall of the device, which converts three phase input voltage to appropriate DC 5 voltages for supplying to said other units.
[0049] The communication unit enables main controller unit to share information with data consolidator unit, other meter devices and display board at user end via communication ports. 10
[0050] The present invention is mountable on din rails including screw mounting feature.
[0051] The present invention is compact enough to be mountable in MCB 15 distribution boards.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0052] Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with 20 the accompanying drawings of the exemplary embodiments and wherein:
Figure 1 and 2 shows: Several external features of device of present invention. 25
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Figure 3 shows: Block diagram of a compact din-rail mountable current limiter with pre-paid multiple source energy meter according to present invention.
Figure 4 shows: Internal arrangement of device of present invention. 5
Figure 5 shows: Internal arrangement of device with some parts hidden in accordance with the present invention.
Figure 6 shows: Rear view of device of present invention.
Figure 7 shows: Different mounting options in given device 10 according to present invention.
Figure 8 shows: Two-step din-clip used in the invention.
Figure 9 shows: Complete views of device with outer dimensions highlighting the compactness of invention.
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DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
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[0053] The instant invention makes a disclosure regarding a technology pertinent to a compact din-rail mountable current limiter with pre-paid multiple source energy meter.
[0054] Accordingly the present invention provides a smart multi-25 functional single system for three-phase pre-paid current limiting as well as energy metering of multiple power sources, in a compact size such that it reduces wiring hassles and can be installed in limited space, even mounted on din-rail which saves time and effort. The
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design is such that it can also be mounted on standard MCB distribution boards. An optimized arrangement of multiple electronic units is done in the energy metering device to render the same compact.
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[0055] The device receives incoming from changeover switches or like devices which shifts load to auxiliary power source such as solar/wind/diesel gen-set etc. when mains power is off and shifts back to mains supply when it becomes available again. Such shifting of power source is done, according to the priority set by user, so that 10 uninterrupted power can be made available.
[0056] Now, reference may be made to fig. 1 and fig. 2 illustrating the external features of the device (1). By means of RJ-11 ports (2) and (3), different devices in the building can be looped in series and 15 connected to a central data consolidator unit (not shown). The RJ-11 port (4) is provided for to and fro data exchange with user display (not shown) installed at consumer end. The incoming and outgoing R, Y, B, N power terminals (5) are provided at bottom side of the device. For safety purposes, the communication ports (2, 3, 4) are covered by 20 shutter (6). Similarly load and source terminals (5) are also shrouded by terminal covers (7). On the front surface of device, an LCD screen (13), a scroll button (14) and an LED indicator (15) is provided. The entire internal assembly, described below, is enclosed inside a base (16) and cover (17). Both of them are sealed against tampering. 25
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[0057] In order to incorporate the circuit in such compact device, the electronic circuit for different functions are smartly compartmentalized and assembled in optimized and judicious manner. 5
[0058] Referring to fig 3 indicating block diagram depicting the inter-linkages of different units including Main Controller and Energy Metering Unit (100), Current limiting Unit (200), Power Supply Unit (300), and Communication Unit (400). Each of the units is having 10 individual electronic circuit boards leading to easy repair and maintenance.
[0059] Now reference may be made to fig. 4 and fig. 5. Here, fig. 4 shows internal assembly of the energy meter, while fig-5 shows the internal 15 assembly after removing main controller and energy metering unit (100) and terminal covers (7).
[0060] Inside the meter’s enclosure, the incoming phase terminals (R, Y, B) are connected to three incoming copper bars (8) which pass 20 through three toroidal core current transformers (9). Current in each phase is sensed, which is passed on to main controller and energy metering unit (100).
[0061] When over-loading occurs on any of the three phases, main 25 controller unit 100 senses the same and signals to current limiting unit 200. This unit 200 actuates the relay (10) (normally closed by
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default) which cuts-off that particular phase. Loads on other phases continue to run.
[0062] This way, while ensuring minimal disruption, the consumer is also warned regarding withdrawal beyond stipulated limits which 5 may be harmful or detrimental to source stability. When the load is reduced by user, it resumes connection once again and normal working state is restored. Current limiting option is available for all the sources whether it is mains/solar/diesel/wind etc. This way meter has integrated overload protection for both source and load at 10 consumer end. Outgoing phase copper bars (11) connect relay output to outgoing terminals. The incoming and outgoing neutral terminals are further shorted via a copper bar (12).
[0063] The main controller and energy metering unit (100) is placed 15 above the CTs (9) and incoming/outgoing copper bars (8, 11). The current limiting unit (200) is positioned above relays (10), adjacent to main controller unit (100).
[0064] Main controller unit (100) performs energy metering function and 20 stores the information about electrical units consumed by different sources individually in memory thereof. It also senses various parameters such as real-time power consumption (active power/apparent power/reactive power), voltage, current, frequency, power factor, kWh units till date, the source which is running 25 currently, remaining rupee balance etc. LCD screen (13) placed above the main PCB and visible from front of device, continuously displays date, time, above electrical parameters, and token balance available.
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Scroll button (14) is provided on main unit (100), accessible from the front of device. It can be used to manually scroll through the various parameters. An IRDA port (not visible) is provided on main unit (100) for updation of tariff rate using a hand-held device (not shown). An LED (15) is fitted in main unit (100) such that it is visible on front 5 surface, which blinks at the rate of say, 1600imp/KWh and is employed for calibration purposes.
[0065] This meter can be recharged in a pre-paid manner by token based system. The token is entered by user via display unit. Said meter gets 10 recharged by designated amount when it receives the token number through port-4 (shown in Fig. 2). Prepaid facility provides user the freedom to choose the amount he wants to spend on the energy.
[0066] According to the recharge amount and tariff rates for different 15 sources, the main unit is programmed to calculate how much balance amount is left. When entire prepaid balance is consumed in terms of energy, it cuts-off the relay outgoing. An anti-tampering sensing button is also installed in main PCB which is as per industry standards. 20
[0067] In order to incorporate such complex circuitry in compact device, and for effective utilization of space, the electronic circuit board for main controller and energy metering unit (100) is designed to be four layered. 25
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[0068] The power supply unit (300) is located in parallel to the side wall of device, which again contributes to compactness of device. It comprises of a switched mode power supply system. It converts three 5 phase input voltage (from incoming R, Y, B, N lines) to appropriate DC voltages, which is provided to other units.
[0069] The communication unit (400) enables main controller unit (100) to share information with data consolidator unit, other meter devices 10 and display board at user end via RJ-11 communication ports 2, 3 and 4. Communication is done by means of RS-485 wired communication protocol. This unit is placed next to main unit (100). It receives information about which source is running via external signal through ports 2, 3 and passes on this information to main unit 15 (100).
[0070] One unique feature of this device, besides compactness is the installation flexibility. For this different mounting options are given.
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[0071] Referring to the figure 6 and 7, mounting is possible on two types of din-rails – whether 35mm din rail (18) or 74 mm din rail (19). On the back surface of meter, integral recesses are provided for mounting on standard top hat type of din-rail. The upper recess (20 or 21) engages with upper flange of din-rail. Lower recess (20’ or 21’ 25 respectively) engages with lower flange of din-rail and the two-step din-clip (22) as shown in figure 6. The device also has general screw-mounting feature (23).
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[0072] Now, reference may be made to fig. 8. Two-step din-clip (22) locks the meter appropriately on both sizes of din-rail. The edge (24) engages lower flange of 74mm din-rail (19) between itself and the meter’s back surface. Similarly the edge (25) engages lower flange of 5 35mm din-rail (18) between itself and meter’s back surface. For removal of the meter, din-clip can be pulled down using screw-driver or hand, which disengages the locking with lower din-rail flange.
[0073] Further, the energy meter according to the present invention can 10 also be installed in MCB distribution boards. The height of meter and its top section compliments the dimensions of modular switchgear devices like MCB, Isolator, etc.
[0074] The top section (26) has same profile as modular circuit-breakers, 15 hence when installed in commonly available MCB distribution boards, it emerges out of the cut-out in DBs, for easy viewing of various parameters.
[0075] Figure 9 shows the final assembly of an exemplary embodiment of 20 proposed invention with different views and outer dimensions. This highlights the compact nature of device of the invention.
[0076] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such 25 variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM:
1. A compact din-rail mountable current limiter with pre-paid multiple source energy meter comprising main controller and energy metering unit, current limiting unit, power supply unit and communication unit provided in connection, atleast one of which 5 has individual electronic circuit board and a multiple layered structure.
2. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in claim 1 wherein said 10 device is mountable on various sizes of din-rails and also screw-mountable.
3. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in claim 1 or 2 wherein a 15 plurality of ports are provided for connecting the device to external units such as central data consolidator unit, other meters, and user display unit for to and fro data exchange and three-phase incoming and outgoing power terminals are provided and wherein these ports and terminals are covered by means of terminal covers 20 or shutters.
4. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in any of the preceding claims wherein the incoming phase terminals are connected to 25 respective incoming copper bar passing through respective toroidal core current transformer.
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4. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in any of the preceding claims wherein the main controller unit senses the current in each of said phases and signals to the current limiting unit, which actuates a relay to cut-off the particular phase in case of 5 occurrence of over-loading on any of the phases.
5. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in any of the preceding claims wherein the outgoing phase copper bars connect relay 10 output to outgoing terminals, in which the incoming and outgoing neutral terminals are shorted via a copper bar.
6. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in any of the preceding 15 claims wherein the main controller and energy metering unit is placed above the CTs and incoming/outgoing copper bars, in which the current limiting unit is positioned above relays, adjacent to the main controller unit.
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7. A compact din-rail mountable current limiter with pre-paid multiple source energy meter as claimed in any of the preceding claims which includes the multilayered main controller and energy metering unit, that senses various parameters such as 25 real-time power consumption (active power/apparent power/ reactive power), voltage, current, frequency, power factor, kWh units till date, the source which is running currently, remaining
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rupee balance etc; a display to indicate date, time, electrical
parameters, running source and leftover prepaid balance; and a
scroll button, an IRDA port and an indicator on the main unit.
8. A compact din-5 rail mountable current limiter with pre-paid
multiple source energy meter as claimed in any of the preceding
claims wherein the power supply unit is located in parallel to the
side wall of the device, which converts three phase input voltage
to appropriate DC voltages for supplying to said other units.
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9. A compact din-rail mountable current limiter with pre-paid
multiple source energy meter as claimed in any of the preceding
claims wherein the communication unit enables main controller
unit to share information with data consolidator unit, other meter
15 devices and display board at user end via communication ports.
10. A compact din-rail mountable current limiter with pre-paid
multiple source energy meter as claimed in any of the preceding
claims which is mountable in MCB distribution boards.