* Three phase active electric energy measuring and no calibration needed within service life; * Prepayment energy consuming system by use of CPU type IC card, Protecting against tamper & fraud ; * One meter with one IC card which adopts special security measures, safe and reliable; * Warning when residual energy is deficient to remind users of purchasing energy in time, trip at overload automatically and recording the numbers of tripping; * Multi-rate function: three tariffs, twelve time sections; provide total reactive energy data; * Display remaining energy, accumulated energy, alarming energy limit, preset load-limit, consult energy ; * Wide limit temperature range * No deviation occurred under normal delivery condition, calibration is unnecessary before installation and random installation location.