How to log voltages in 220v network on arduino?

Question

Arduino

Gentlemen, help me solve the problem of logging the voltage in the network.
How much I searched on the Internet and did not find an AC voltage sensor for arduino.
There is an ACS712 for current, but no voltage.
Maybe I searched badly?
Ideally, I need something that can collect voltage from more than one input and pass parameters to the arduino.

Answer 1

So for anyone it will be necessary to have some kind of ADC, if you fence on a discrete ADC, it will turn out too difficult. Perhaps it is easier to develop a voltage measurement module on the same arduino with an 8-channel ADC and I2C output.
Separately, there is the question of galvanic isolation ... You can power this module through a 1: 1 voltage transformer and transmit data through an optocoupler, or you can galvanically decouple each input, but this will become too expensive - galvanic isolation modules, as used in oscilloscopes, cost from $ 50 a piece. But on the other hand, there will be no need to worry about different phases of voltages at individual inputs.
Well, in the end = ends, the cheapest way is to use low-power transformers for each input - there are transformers for 0.6W @ 6.3V with dimensions of 20x30mm - and galvanic isolation is for you, and cheap.

Answer 2

Might be worth picking it up yourself?
For example: http://cxema.my1.ru/publ/teorija/izuchaem_mikrokontrolery/tipovye_schemy_uzlov_vvoda_mk_datchiki_naprjazhenija_set_220_v/33-1-0-2430