Hello,
I am setting up a system based upon a NI 9183 cDAQ chassis.
My aim is to build a robust system against EMC to do some analog measurements in a noisy environment.
I have connected all cable shields and hardware chassis to a shared protective earth (PE) point. This connects directly to the building PE through a schucko plug. The PSU used to power sensors, cdaq etc. is double isolated hence it has a floating +V and GND. If I measure between PE and my +V I read about 120VAC (this is also present on the GND line, very low current on both ) supposedly leaked by the Y capacitors in the PSU. To avoid this, I bond GND to PE at the PSU, this should be my only intentional connection point between PE and GND to avoid ground loops.
I have however noticed that the C screw terminal (-V, i.e. my GND) on my NI 9183 is bonded to the PE chassis screw (less than 0.3ohms), producing in this case a second bond and ground loops. Can I remove my GND and PE bond at the PSU and just leave the internal cDAQ bond as my sole star point?
I am not very experienced in this topic, so please if I am misinterpreting something or there is another way of going about this please let me know!
Thank you very much!
