adopting advanced microelectronics, lsic, digital processing technology and smt technics, our newly developed dds1661din rail mounted single phase kwh meter utterly conform to the relative technic requirement of grade 1 single phase kwh meter of iec 62053-21. it can precisely calculate the active energy loss of rp 50hz or 60hz single-phase ac network. reliable, small size, light, gorgeous and easy installation, it is widely-used and convenient collaborating.