Title of Invention

CARD OPERATED PREPAID ENERGY METER USING NOVEL CARD READING TECHNIQUE

Abstract

ABSTRACT CARD OPERATED PREPAID ENERGY METER USING NOVEL CARD READING TECHNIQUE A card based prepaid electrical energy meter comprises an electrical energy meter <2>, a prepaid programmed card (7) and a DC power supply (1) for the electronic circuitry. A novel card reading mechanism (6) is used for bidirectton transfer of data between the card and the meter. A microcontroller based control unit (5) reads the data from the card and controls/coordinates the metering activities. A load controller (4) is connected to the control unit (5) for connection and disconnection of mains AC power supply to a load (3) depending on existence of credit units of energy.

Full Text

The present invention relates to a card based prepaid electrical energy meter. Known prepaid energy meters using commercially available card readers are qui te expensive. In the present invention the reader with its associated software is embedded into the microcontroller, thereby making the system compact and cost effect ive. One object of the present invention therefore is to provide a prepaid electrical energy meter with a novel card reading technique. In the prepaid electrical energy meter of the present invention the consumers have to purchase energy units in advance of i ts consumption. The number of uni ts purchased is programmed on a card by the card vending machine, which can be located at the utility, for example at the electricity board or at its identified paints of sale. A load controller and a re lay are provided for connecting the supply to the load. The energy measurement section of the system cont inuously measures the energy consumption and the d isplay is updated accordingly. Advance notice can be given to the consumer that the available credit is nearing exhaustion at about 25K balance credi t. The supply is cut off from the load when the amount becomes equal to the purchased amount, unless fresh credi t has been obtained. After the meter accepts the fresh credit it will automatically restore supply to the consumer. The card reader to be used in the acheme of present invention consists of hardwares like smart card socket and associated circuitry together with unique customised software. The smart card sockets have been tailored to suit the requirement of reading the data from the card into a microcontroller based control unit. The control unit controls and coordinates all the metering activities. The card reading software is integrated into the microcontroller. Apart from reading data from the card, the mechanism will also write any information relating to the meter tampering status onto a card. This information can be read from the card by the ut i1i ty. The card reading mechanism enables bi-directional data transfer from the card to the meter and transferring the data from the meter to the card. Thus the present invention provides a card based prepaid electrical energy meter comprising: an electrical energy meter; a prepaid programmed cardj a DC power supply for electronic circuitry; a card reading mechanism for bidirectional data transfer between said card and said meterj a microcontrol1er based control unit for reading the data from the card and control1ing, coordinating the metering activities; and a load controller connected to said control unit for connection and dis¬connection of mains AC power supply to a load. The card based prepaid electrical energy meter of the present invention will now be described in detail referring to the accompanying drawing where; Figure 1 shows in block diagram form the prepaid energy meter of the presesnt invention. The consumers purchase the pre—paid card from a card vending machine The card vending machine is a microcontroller-based unit that is operated through a keypad. This is used to program the number of units into the consumer's card for which he pays in advance. In addition to the number of units, the type of installation (LT/HT> and the consumer number can also be programmed through the vending machine. The vending unit can also read the information on the card. It can be located at the utility, for example, the electricity boards or at the counters identified by the electricity boards. It consists of an LCD display that displays the data programmed into the card. A card reading mechanism 6 is used for bidi rection data transfer from a card 7 to an electrical energy meter 2 and from the meter 2 to the card 7. The card reader fa for the data transfer has been built into the control circuit with a software embedded into a microcontroller based control unit 5. The card reading mechanism comprises an 8-pin friction (or sliding) switch/socket interfaced to the microcontroller 5. When the card 7 is inserted into the socket, it is sensed by the microcontroller 5 that looks for data in the card 7. If it is a programmed card (with credit energy units), it reads this information and saves it in a non-volat ile memory. The card 7 is subsequently erased and the same card can be re-used. Also, in case the meter 2 has been tampered by wrong connection at the terminal block, this information is written on the card 7 by the meter 2 during the credit entry. The electricity board personnel can read this information during the next purchase of credit units by the user. The microcontroller based control unit 5 is used for reading the data from the card into it and for controlling and coord inat ing the metering activities. The actual energy (kWh) consumed is measured by an energy measurement ASIC ( Application Specific Integrated Circuit). The microcontroller reads the purchased energy from the card which has been programmed at the utility end and stores it in a non--volatile memory 4 after it cross-checks the meter consumer number. It then switches ON a relay 4 to establish supply to a load 3. As the energy is consumed, i t computes the net credit energy available and this information is also stored in the non^volat ile memory. The net credit energy and time are displayed on a LCD display 8. After 75X of the initial credit energy is exhausted, the microcontroller generates an LED and buzzer alarm to indicate low credit. Subsequent to this, it checks continuously for insertion of new card with credit. If additional credit is introduced, it adds this to the existing credit and re-computes 25*/. credit and continues operation. The 25X credit alarm is turned off. If fresh credit is not added, the meter continues to operate till credit reaches zero.The microcontroller 5 switches off the relay 4 and thereby cuts off the power supply to the load 3. A display and/or alarm is provided ( not shown) for dispi aying measured energy consumption and for giving an alarm before credit units are exhausted. The front panel of the meter can comprise of an 16 x 1 alphanumeric LCD display that displays the net energy at any point of time and also the time, ftpart from this it also has one LED for calibration, 2 LED for fault indication { one for reversal of current polarity and the other for earth loading > that are generated by the energy metering ASIC, one LED for 25*/. credit and one LED for zero credit indication. The microcontrol1er displays the credit an the LCD display and also initiates the alarms. A load controller comprising a latching relay 4 is used for connection and disconnection. The microcontroller 5 controls the operation of the load controller. On existence of a valid non-zero credit,the microcontroller 5 sufi tches ON the rel ay 4 and establ ishes supp ly to the load 3. When the credit reaches zero, the relay is switched OFF. WE CLAIM: 1. A card based preoaid electrical ener-gy meter comprising s - an electrical energy meter - a prepaid prpgrammed card (7); - a DC Power supply (1) for the electronic circuitry - a card reading mechanism (6) for bi-directional data transfer- between said card and said meter; - a microcontroller based control unit (5) for reading the data from the card and controlling, coordinating the metering activities; and - a load controller (4) connected to said control unit (5) for connection and disconnection of mains AC power supply to a load (3) depending on existence of credit units of energy. 2. The energy meter as claimed in claim 1 wherein said control unit (5>is configured for directly controlling transfer of data between the card reacting mechanism 3. The energy meter as claimed in claim i wherein said load controller comprises a latching relay (4). 4. The energy meter as claimed in claim i, wherein said energy meter (2) comprises a front panel for providing alphanumeric LCD display of the net energy. 5. The energy meter as claimed in the preceding claims wherein said control unit (5) is configured to display the 25*/. credi t and zero credi t an said LCD display and to initiate the alarms. 6. A card based prepaid electrical energy meter substantially as here in described and i1lustrated in the accompanying drawing.

Documents:

0443-mas-2002 abstract.pdf

0443-mas-2002 claims duplicate.pdf

0443-mas-2002 claims.pdf

0443-mas-2002 correspondence-others.pdf

0443-mas-2002 correspondence-po.pdf

0443-mas-2002 description (complete) duplicate.pdf

0443-mas-2002 description (complete).pdf

0443-mas-2002 description (provisional).pdf

0443-mas-2002 drawings duplicate.pdf

0443-mas-2002 drawings.pdf

0443-mas-2002 form-1.pdf

0443-mas-2002 form-19.pdf

0443-mas-2002 form-26.pdf

0443-mas-2002 form-3.pdf

0443-mas-2002 form-5.pdf