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Why 4-20 mA signal is preferred over a 0-10V signal?

Answers:

Generally in a transistor some amount of voltage is required for turning it on. This voltage is the cut in voltage. Up to this voltage the exists a nonlinearity in its characteristics. Beyond this cut in voltage the char. of transistor is linear. This nonlinear region lays between 0-4ma, beyond 4ma it linear. This is why 4-20 ma range is used.

Yes

If the control cable is get damaged then it will report to plc ( controller)...so it will help to know it is not communicating...

As voltage signal is affected by an external noise but current cannot be affected that's why 4-20 mA signal is preferred.

because when a signal wire 0-10v goes too far or too long there' s a voltage drop. but if you used 4-20mA current signal you will get the same signal of 4-20mA even your signal cable is very long.

yes

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