canu tell me why 4-20 ma and why not this 3-25ma?please
give reason of this value.

Answer Posted / jose

Instruments have a nominal resistance of 250 ohms. With
that, the usual output of field instruments is 1-5 volts or
4-20 mA. If you put a 250 ohm resistor on a 1 volt output
the the result will be .004 amps or 4 mA. The same holds
true if you put a 250 ohm resistor accross a 5 volt output
you will get .020 amps or 20 mA.

Is This Answer Correct ?    32 Yes 9 No



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