Why 24VDC power Supply is used as standard for all loop
powered transmitters?
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Answer Posted / lokendra
dear friends
as per ISA standards 24 VDC is the minimum possible voltage
at which the spark will not come,we know our transmitters
will give max output current of 27 mA here they have limit
this current bcause the power we get is less than 1 watt
(P=VxI)648mW which is not capable of producing a spark thus
they have avoided spark generation by selecting 24 VDC and
limiting currnt to 27mA.this comes under extrisic safety.
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