Digital Watthour Meter Auto-Calibrate Using Microprocessor (original) (raw)

This paper introduces the design of a Single-phase watthour meter auto-calibrating. The important advantage of the watthour scale is the multiplication is done by the newly developed self-calibration multiplier (SCM) with superior stability. The self-calibration multiplier IC applies an analogue multiplier to perform the multiplication, detects and also compensates for large sources of error caused by changing the multiplication parameter including the output offset. According to this result, the self-calibration multiplier has stable input and output characteristics. The correction of the multiplication factor is based on an IC reference voltage that uses the Zener diode. Consequently, the stability of the self-calibration multiplier and the meter depends on the reference voltage stability. While the other pieces are additional circuits to adjust the zero load and the unnecessary full load.