why 4 to 20 ma ,why not 0 to 20 or 3 to 15 or anything
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Answer Posted / wilson
Most people has got the answer correct for "why 4-20mA and
not 0-20mA". Yes, it is to prevent undetected failure of
circuit or instrument.
As for "why not 3 to 15 or anything". I assumed the
question is not "why not 3-15mA" because not one use 3-
15 "mA", if really you have to ask that, you might as well
ask why not 2.314 to 33.776 mA.
3 to 15 is used, but in pneumatic system and the unit is in
PSI. i.e. 0.2 to 1.0 bar. The reason for 3PSI (or 0.2bar)
is the same as 4mA, to prevent undetected failure.
| Is This Answer Correct ? | 17 Yes | 10 No |
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