Why we are using 4-20 mA as Analog signal transmission
other than 3 to 19 or 2 to 18 or 6 to 22 like wise ? What
is the reason behind using 4 & 20 mA? Can anyone give
proper technical reply ?

Answer Posted / ahmad

1- Any electronic circuit having its error, here Ico=3.85 ma(aprox=4 ma). that is why we do start from 4 ma.
2- it is also convertable to 1-5 volt, with precision resistance of 250 ohms.

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