I have been testing an industrial system. I have developed a test device to properly test this industrial system. I am currently finalizing the test device and have put it in an enclosure to EMC proof it from external sources.
When probing around the industrial system with my multimeter I discovered that in the industrial system the 0V is connected to the EARTH(enclosure) via a 200k resistance. I don't know where the connection occurs, but I was a little surprised.
It does not seem to make sense cause this way, you loose the EMC proofing, right? Since the test device is also connected to the 0V it also looses its EMC proofing... The industrial systems' main components are a AC Drive, PLC and Power Supply. But I would suggest these components are designed to act as floating components if not EARTHed by the user.
Since I'm not the designer of the Industrial system and due to company rules, I can't go in depth on its workings and function. Though I am surprised that the EARTH connects to 0V.
Maybe an experienced engineer can enlighten me with some information on EARTHING, 0V reference points and EMC in industrial systems?