There is a potential difference of around 12V between the instrumentation circuit and the electrical circuit
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The PLC system of the lean liquid pump in our factory shuts down frequently due to vibration, but the vibration sensors appear to be functioning normally. There is a potential difference of around 12V between the instrument ground and the electrical ground; we suspect that this is caused by interference, but the source of this interference has not been identified yet. In order to eliminate this potential difference, it’s not possible to connect the negative terminal of the instrument to the instrument ground (as this results in a power loss). Could anyone help us determine what might be causing this issue?
According to the specifications, the instrument panel should be connected to the electrical plant’s grounding grid; otherwise, a potential difference will occur.
If you don’t understand, don’t act foolishly. No matter how it’s done, a factory grounding system has only one ground point, you know? Otherwise, a potential difference will arise. Those who work with instruments understand what P-grounding is.
It would be best to provide a wiring diagram. This kind of situation often occurs with the connection of instruments and control systems. The grounding method is indeed very important; if it’s difficult to resolve, an isolation-based connection method can be used ； Or can the instrument side be handled at ground potential?
When the instrument ground and the electrical ground are not connected together, there shouldn’t be a 12V potential difference. Either there is a problem with the electrical system, or there is an issue with the instrument ground, or the neutral and ground wires in the electrical system are connected together, or there is a device causing leakage current. It is recommended to check the grounding and measure the ground resistance; if the problem cannot be resolved, considering using a relay to isolate the electrical instruments electrically may be an option.