DTSD8777 、 DSSD8777 series three-phase electromc multi-function watt-hour meter is a new generation product that can measure reactive energy and active energy with multi-tariff, it is designed by modularization, its multi functions can be combined freely to meet users requirements. Each performance index of it conforms to standard DL/T 614-1997 Multifunctional Watt-hour Meter and standard DL/T 645-1997 Multi-function Watt-hour Meters Communication Protocol as well as total technical requirements for three-phase electronic multi-function watt-hour meters stipulated in standard GB/T17 215.321-2008/IEC 61036.