The model DDS3666 &DTS3666 wall amount single-phase & three phase electronic meter is designed to measure active electric energy in a single-phase circuit with a 50Hz/60Hz reference frequency. It features excellent accuracy, reliability, stability and feasibility. It is integrated with internationally advanced ultralow power consumption LSIC, microprocessor and SMT technique. Using international brand long-life devices as its key parts increases its reliability and service life. The manufacture of the product complies with all technical indexes of IEC 62053-21 Class 1  AC Active Watt-hour Meter and GB/T17215.321-2008 Class1  Alternating Current Active Energy Meter for the single-phase static &three phase watt-hour meter.