Answer Posted / saravanamurthy

Hi,

4-20 mA standard is mainly to differentiate the conditions
live zero and dead zero i.e let me tell an example consider
a level sensor fixed in a tank . now the tank is empty .
then the sensor will send the reading as 0mA this zero is
live zero, if there is no standard as 4-20mA. in the same
case if there is any problem in the sensor output then also
the reading ll be 0mA this zero is Dead zero.In order to
differentiate the fault and the original process condition
we have chose this range as the standard.

Thanks & Regards,

S.I.Saravanamurthy.

Your comments are welcome

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