Overall charcteristics of prepaid energy meter Methodology. Collection of revenues. Loading the credit revenue into the meter. Decrementing the revenue. Providing the alarm. Disconnection. Security of transactions. Unloading the revenue.
Components of prepaid energy meter EEPROM IC (Smart card) AT89S52 16*2 LCD ULN2003 AT2402 Digital energy meter
EEPROM IC It is called as smart card. It is a electrical erasable read only memory. It is to upload the amount recharge in form of electrical energy. The contents are automatically deleted once it is inserted inside the card reader.
AT89S52 It belongs to family of microcontrollers. It has total 40 pins. 32 I/O lines. 8K flash memory ROM and 256K RAM. It operates at 33KHz frequency. Addressing similar to 8051 microcontroller. Only pin nos 12,31,40,34-39,22,21,25,28 are used for our purpose.
ULN2003 It consists of seven independent darlington connection. It acts as a current amplifier circuit. It is used to run a high voltage/current peripheral circuits. When input terminal is high it offers low impedance path other wise it offers a high impedance. Any two input and output are used for our purpose.
AT2402 and 16*2 LCD display Chip is used to read data from eeprom through card reader. All the data are transmitted serially in 8 bit words. It also verifies the code prior to read operation(PSC). 16*2 LCD display has two row screen and each row displays 16 digit at a time. It also acts as a tariff indicator, indicates amount of electricity consume and remaining.
Working principle of digital energy meter Output in form of frequency. Energy consume proportional to output frequency. Relatively cheaper meter. Human error are reduced while calculating. Opto coupler is used for calculation of pulses. Output frequency can be selected for other purpose also , such as running a stepper motor an electromagnetic register.
Benefits to consumers Pay as you go. No need to stand in queue. No surprising bills. No bill disputes. Allow customer to budget expenses. Help customer contribute towards energy conservation.
Benefits to utilities Up front payment for electricity. Lower overheads. No billing hassles. No disconnection/reconnection. Tamper and fraud detection. Money and time based load connection and disconnection. Load/demand control.