For a precision and simultaneous analog signal data acquisition; several force, temperature and acceleration transducer outputs are coupled to a daq board input channels through signal conditioning modules for each channel. These modules acts like differential inputs they have very high CMR, they provide ch-ch isolation and also provide built in anti-aliasing filters.
So far so good, but I still have AC line interference coupling through power supplies. And if I connect power supply DC ground terminal to earth terminal the interference disappears.
I tried to draw the scenario below where switches indicates connection option between the power supply DC ground and the earth. In the diagram two channels shown as example and in real there will be around 15 where cable lengths are around 12 meters:
Is there any issue with such a scheme for the above diagram? I know if there would be no isolation modules there would be ground loops but in this case there seems to be complete isolation but still I don’t have more experience beyond this argument for the overall system here.