A 3 Phase Digital Watthour Meter

Abstract:    This paper describes a microprocessor-controlled three-phase digital meter. The wattmeter is based on the sampling method and, on analogue-to-digital conversion; a single A/D converter ten-bit, built into the microprocessor is used. Transformer accuracy is demonstrated by overlaying noise on current and voltage signals and reducing uncertainty with an external resistive voltage divider. The wide range of current of passing voltage signals, in proportion to the input currents, through a programmable gain amplifier. The total counter pigment is not more than 0.1 per cent.