This application describes a low-cost, high-accuracy watt-hour meter based on the AD7755. The meter described is intended for use in single phase, twowire distribution systems. However the design can easily be adapted to suit specific regional requirements, for example in the Malaysia power is usually distributed to residential customers as single-phase, three-wire. The AD7755 is a low-cost, single-chip solution for electrical energy measurement. The AD7755 is comprised of two ADCs, reference circuit, and all the signal processing necessary for the calculation of real (active) power. The AD7755 also includes direct drive capability for electromechanical counters (i.e., the energy register), and has a high-frequency pulse output for calibration (CF). The AD7755 provides direct drive capability for this type of counter. The AD7755 also
provides a high-frequency output at the CF pin for the meter constant (3200 impulse/kWh).
The test circuit from datasheet AD7755
The picture of AD7755 that I ordered