General Introduction: Adopting special integrated circuit and manufactured with advanced SMT and re-flow soldering technology, DDSIY22 Single Phase Power Line Carrie Prepayment Electronic Meter can be used for measuring active and reactive electric power that requires both timesharing and prepayment. Large LCD displays energy consumed in big characters. The circuit design and component selection allow maximum tolerance thus the meter can run with stability, accuracy, high overload, low power consumption and reliability. Functions and Characteristics: Positive/negative active energy consumption measurement( negative active energy consumption will be counted into positive active energy consumption) CPU card prepayment, purchasing before using. Alarm at low remaining power to remind user of timely purchasing Carrier Wave communication through power lines with automatical relay function The meter can allow credit consumptions and the debit can be subtracted in the next transaction Load Control function and load can be setted. Real time clock The real status of relay can be checked automatically. Energy consumption frozen and stored function