Do the electrical ground and the instrument ground need to be connected together?
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As the title suggests, in a factory, should the electrical ground grid and the DCS grounding system be connected together? Some believe that they should not be connected, out of concern that lightning waves from thunderstorms might penetrate into the DCS through the electrical ground grid. Others think they should be connected to prevent potential differences from arising. Please discuss the actual situations in your respective companies and provide your opinions
Comply with the \"Code for Design of Grounding of Instrumentation in Petrochemical Industries\" SHT 3081 and the \"Code for Design of Grounding of Instrumentation Systems\" HG/T 20513-2014.
Both of these specifications require connection to the electrical ground, unless the resistance of the electrical ground network is greater than 4 ohms
From a regulatory perspective, there should be no problem connecting it to the electrical grid. However, I have also seen drawings produced by some DCS manufacturers that separate electrical grounding from instrument grounding. In practice, what I often encounter is that the protected areas are connected to the main grounding grid, while separate grounding piles are used for the instruments.