[attachment=14190]
FIG.1. BLOCK DIAGRAM OF PRE PAID ENERGY METER
The aim of this project is to design a prepaid energy meter to monitor the consumption of electricity in domestic needs. The standard business model of electricity retailing involves the electricity company billing the customer for the amount of energy used in the previous month or quarter. In some countries, if the retailer believes that the customer may not pay the bill for what ever reason a prepayment meter may be installed. This requires the customer to make advance payment before using the electricity. If the available credit is exhausted then the supply of electricity is automatically cut off by a relay.
Here analog energy meter is replaced by a digital energy meter. The digital energy meter used here is a high accuracy, low cost, single phase power meter based on the ADE7757.The meter is designed for use in single phase 2 wire distribution system. A relay is connected in between power lines and the load. The relay is controlled by the primary controller.
Microcontroller 89C51 acts as the primary controller. The primary controller collects information from digital energy meter as well as from the smart card. Smart gives information about the limitation of units. The digital energy meter reading is compared with the smart card information by the primary controller and hence suitably primary controller controls the relay.
CIRCUIT DIAGRAM:-
FIG. 02.BLOCK DIAGRAM
COMPONENTS DESCRIPTION:-
1. I.C.’S:-
(A.) AT89S52:-
FIG. 03.I.C.AT89S52
Description:-
The ISL8200MMREP is a simple and easy to use high power, current-sharing DC\DC power module for Datacom\Telecom\FPGA power hungry applications. All that is needed is the ISL8200MMREP, a few passive components and one VOUT setting resistor to have a complete 10A design ready for market.The ease of use virtually eliminates the design and manufacturing risks while dramatically improving time to market.Need more output current? Just simply parallel up to six ISL8200MMREP modules to scale up to a 60A solution.The simplicity of the ISL8200MMREP is in its Off The Shelf, unassisted implementation. Patented current sharing in multi-phase operation greatly reduces ripple currents, BOM cost andcomplexity.
The ISL8200MMREPs thermally enhanced, compact QFN package, operates at full load and over-temperature, without requiring forced air cooling. It's so thin it can even fit on the back side of the PCB. Easy access to all pins with few external components, reduces the PCB design to a component layer and a simple ground layer.
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8Kbytes of in-system programmable Flash memory. The device is manufactured usingAtmel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pinout. The on-chip Flash allows the programmemory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.By combining a versatile 8-bit CPU with in-system programmable Flash ona monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides ahighly-flexible and cost-effective solution to many embedded control applications.The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytesof RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, asix-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator,and clock circuitry. In addition, the AT89S52 is designed with static logic for operationdown to zero frequency and supports two software selectable power saving modes.
The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, andinterrupt system to continue functioning. The Power-down mode saves the RAM contentsbut freezes the oscillator, disabling all other chip functions until the next interruptor hardware reset.