Main Features: 1. Accurate active energy measurement for long-term operation without calibration under normal operation condition; 2. IC card is adopted for prepaid energy consumption and able to display current read/surplus/accumulated/ energy value, preset permitted load value, alarming energy value, max load; 3. Alarm at low remaining power and switch off the power supply (power supply can be switch on by inserting user card) to remind the user of timely purchasing; 4. Recording the extraordinary events, automatically recording all data of illegal energy consumption events; 5. Reading user ID number and accumulated energy consumption by using collection card; 6. Featuring with tamper and fraud proof by using unique card for each user; 7. Large current capacity latching relay with low power consumption and high reliability; Switching off power supply and record No.s of the event in case of overload; 8. Provided both photo-electric insulated impulse test output and LED test output.