A Low Cost, High Accuracy Watthourmeter

P. Petrovic (Yugoslavia)


electric utilities, dual-slope ADC, stroboscopic technique, watthourmeter.


This paper present a novel design of a high accuracy watthourmeter based on use of very slow, high precision and cheap dual slope A/D converters. Measurements of voltage and current are made in successive periods by a stroboscopic technique (synchronous undersampling). The assumed stationary of the electric utilities is validated by measurements with an experimental setup, consisting of a fast high precision sigma-delta ADC. The necessary synchronization is reached by software measurements of the frequency of the measured signal. Measurements performed on the electric utilities in Yugoslavia indicate that the voltage and current waveform remains unchanged while the required accuracy is maintained, so the error made when sampling during several periods is below the value required for class 0.1 instruments

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