Thank you very much for the reply, I forgot about an Schematic I will put it later.
I know what is power factor in the transmission, but my project is for power monitors as you said.
When I said " the error in Power Factor was terrible for small currents". The real problem in this was the consequences in other values, The EMON meter shows Real Power, Apparent Power and Reactive Power and all of this depends of the Power Factor Value, all this values was OK including in the low currents, the problem was when the Harmonic Content was high, And if you are metering small currents and non-lineal loads this meter does not works. I know this because I was using a fluke power meter and comparing the results.
The Acuvim-L not only shows Power Factor, It also has a large table of Values, Depending of the Model, In my case Acuvim-DL
and remember all is in three phase. Also it reads energy parameters, In my case i don't use it, maybe somebody is trying to read this somewhere and this is very useful.
But Why to do this?? The simple answer is to make one low cost power control. I am doing a project for control some non-lineal loads and that was the reason for making it works.
All the table is showed in this pdf, also there is the addresses of Modbus parameters.: