Sriharsha Vedurmudi wrote:
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...Coming to your caution, can you please elaborate on the harm, the environment can cause on these sensor lines. Its nothing more than a meger contact (ON/OFF). What can go wrong?


Harsha,

Please THINK ! THIS IS THE REAL WORLD EVERYTHING GOES WRONG.

Is this a critical system ? YES.
How should it fail safe ?
How do I monitor sensors to make sure they are still valid ?
Will it handle the idiot who tests the system with a Megger (earth leakage tester)
Will it handle an idiot that connects it to a three phase supply ?

How will you screen for conducted interference, how do you stop your cables to the sensor from radiating ?

Think of the most crazy faults you can. THEN you can discount them, but only when you have thought hard about them.

Steve