Hi,
I have to measure voltages of an galvanic isolated system with ADCs. The V_IN voltage is around 70V DC or 50V AC.
The idea is a difference measurement. It's not galvanic isolated anymore, but isolated through the high input impedance. So it's quasi isolated like differential probes for scopes. In Spice simulations it works very well.

Do you think this will work with an isolated V_IN without destroying anything even at higher voltages (<200V) or make it dangerous for a person?
Because the other grounds in the schematic are the analog grounds for the amplifiers and the ADCs. It's connected to the digital ground in one point. If you think, this will work, I'm unsure where to connect pin 1 of the AD629. Should it be connected to the analog ground or the isolated ground? I guess to the isolated one.
Thanks for your advice.
Best regards
Momchilo