How to isolate analog voltage to feed into ADC!?

[electronicsIUST]

Hi, I want to measure phase to null voltage of a three phase system by using resistor divider and then isolate it and feed it into ADC of MCU. How do I can isolate voltages!? Actually I want to have an output voltage that is the same as input but with different grounds and I don't want to use transformer!

 

[KlausST]

Hi,

It seems you didn't much research on your own:
* transformer
* dedicated isolating voltage sensors
* isolating amplifiers
* linear operating optocouplers
* others

*****
All have their benefits and drawbacks..
Cost, effort, safety regulations, signal distortion, DC voltage, speed, accuracy, drift..

Generally I often prefer to use an external ADC with SPI interface.
Isolate the SPI interface and the power supply.
This usually gives very precise results, because the "isolation" itself introduces no errors.

Klaus

 

[esp1]

hi,
One option would be to use a HCNR200 opto analog isolator.
At the low end of the resistive divider chain, Vsense.
E