Self-calibrating standard watthour meter

A self-calibrating single-phase standard watthour meter is described. The significant feature of the watthour meter is that the multiplication is carried out by a newly developed self-calibrating multiplier (SCM) with excellent stability. The SCM uses an analog multiplying IC to perform multiplication, and detects and compensates for the significant error sources caused by the change of the multiplication coefficient and output offset. As a result, the SCM has stable input-output characteristics. The multiplication coefficient correction is based on a reference voltage IC which uses a Zener diode. Therefore, the stability of the SCM and the watthour meter depend on the stability of the reference voltage. The other features are that extra circuits for zero- and full load-adjustment are unnecessary