The all items of capability standards of DDSY450 series meet the entire technology requirement of the GB/T1860.3-2001?Ammeter with prepaying fee? and GB/T17215-1998?Grade 1 and Grade2 quiescence style power ammeters?IEC 1036-1996 about the singlephase electron style ammeter with prepaying fee. 1.The measure with power electric energy can work for long time without being debugged. 2.Prepaying fee by IC or infrared card. 3.It will remind you when the remnant power is unwrought. 4.It can record the maximal load times happened. 5.Every use has his card all-alone,which possesses the excellent anti-forgoing. 6.It can show the current read power,remnant power,and accumulative total power,alarmed power,maximal overload and current overload. 7.Palmtop computer or connecting card can copy the user NO.and accumulative total power and other data. 8.Wide work temperature range:-25°C~+55°C. 9.It has the function long-distance and electric energy measure impulse outp.