DSSD1789/DTSD1789 three-phase three-wire/four-wire multifunction smart energy meter has the functions of active and reactive time-sharing rate electric energy metering, data processing, real-time monitoring, automatic control, information interaction, etc. It can support three-phase three-wire and three-phase four-wire systems. It is suitable for power plants, substations and various enterprises and institutions with high reliability and high stability electric energy measurement requirements.