We are developing a energy monitoring product in which we are using ADE7763 for calculating VRMS, IRMS, KVA and KW. The readings are matching to external power meter measurements when the currents are above 1A (full range is 40A) and power factor is more than 0.9. We are facing two different problems
1) As the power factor starts decreasing below 0.9 with current more than 1A, KW error goes as high 25%. Whereas VRMS, IRMS and KVA readings are accurate.
2) When the current is quite small (less than 0.8A) with very low power factor (around 0.2), the KW reading goes to MW range. IRMS, VRMS and KVA are accurate in this case as well.
Can anybody explain why we are seeing this behaviour.