different of instrument earth and electrical earth

Ronron,

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Regards,
Sapper

Dear,

Electrical Earth is the earthing grid made for safety of human . Wherein, the short circuit fault currents are passed into the earth, bypassing current path from operating person's body to the earth. same may protect the electrical equipment thru circuit breakers.

Instrument earth is the earthing system made for improvements in reliability / performance of the electronic instruments / plc systems / computers / digital sensors & process instruments , wherein, the leakage currents of electronic cards/ electromagnetic interferences generated currents / harmonics generated currents & voltages are by passed into the earthing system exclusively made for the instruments & other electronic systems.

Both the earthing systems should be electrically & physically isolated.

Best harry potter,

In your reply the above topic, you comment by saying "Both the earthing systems should be electrically & physically isolated". I can think that is true for instruments having their own power supply, but what if a control unit's control electronics OV are connected to the earth of its own power supply. Doing so, will that not provide a return path for noise and interference?