METHOD FOR METERING ELECTRIC ENERGY IN A STATIC ELECTRIC ENERGY METER

摘要

A meter of electric energy that applies the method comprises a multiplexer (40), an A/D converter (50), a micro-controller (60), and a calculator apparatus (70). At a single-phase object, the metering signal (Uu1) of the voltage (U1) and the metering signal (Ii1) of the current (I1) have been connected to the input channels (1...4) of the multiplexer. The current metering signal (Ii1) has been divided into at least two branches, each of which branches has been connected to the input channels (2...4) of the multiplexer by means of an amplifier (3011, 3012, 3013) provided with fixed amplification of different magnitude. The input channels (1...4) of the multiplexer are constantly connected alternatingly to the output interface (15) of the multiplexer. Corresponding to each digital sample of the voltage metering signal (Uu1), for calculation of momentary power, out of the availabe amplified current signals (Ii11...Ii13), the digital sample of the current signal is selected which produces the highest non-saturated result of conversion in the A/D converter at each particular time. The method can be applied in single-phase and three-phase static meters of electric energy.