I use 7880 monitor high voltage like 690V or 1140V,so i want to use voltage transformer, but i don't know if i use voltage transformer ,how to monitor neutral voltage,i upload my sch.I hope you can give me some suggestion.PDF
It is okay to use a voltage transformer, that is indirect metering. For as long as the level on your secondary is within the limit of the analog input channel of the chip. The problem that you will encounter there are phase delay. Which can be solved by calibrating the phase.