DDS901 are 2.0 electronic single phase watt-hour meters. They apply to the working condition of power electricity of 50Hz or 60Hz frequency, -10 50 environmental temperature and the humidity not more than 85%. This meter applies micro-electronic technology to measure the power. It gets voltage sampling signals from the divider. The current divider will get the current & voltage signals from multiplier and through frequency conversion, produce a counting pulse in which the frequency is in direct ratio with the voltage current. Then the counter is driven by frequency dividing stepping motor to meter the power