DDS557 single phase electronic watt-hour meter adopt a large scale of integrated circuits and SMT technology. Type DDS557 single phase electronic watt-hour meter adopt a large scale of ... frequency 50 Hz or 60 Hz single phase AC electricity net and which is installed in meter box indoors or outdoors.Accuracy(Class ... 10A, 10/40A, 15/60A, 20/80A, 20/100A DDS557 single phase electronic watt-hour meter