Answer / 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.

Answer / sivakumar

see all loop powered transmitters are capable of
withstanding 10 t0 36v dc ...as per the process requirement
it will vary.. insome industries they are using 12v dc
also.. 24 vdc is used because as per ISA there are some
standards wich will match other process reqirement like
24vdc relays for digital control also wecan use 24dc to
energize tis relays

Answer / sagar

Because 24vdc is a minimum voltage where no possibilities of any kind of spark.
so we can prevent our costly instuments using 24 vdc.

Answer / venkatesh

all transmitters(24vdc) are using for very imp parmeters , so the 24v dc coming from smps or any dc power units and these working with 230v ac UPS SUPPLY so if anytime some powertrips will come this transmitters still working with on ups supply with smps outputs

Answer / maddy2504

It totally depends, 24 V DC 2 wire is not always applicable
every wehere some times it is 2 wire, 3 wire (2 cable for
power up & signal & 1 cable is for earthing), some times it
will 4 wire(2 for powerup & 2 for signal).

24 V Dc is for certain limit b'coz voltage will be drop in
that case w'll use 230v AC.

Answer / abdul

Give extra power supply damage this device because standard instrument give standard electrical signal 4-20 and 24 V dc

Answer / ankur gupta

it is not possible to design capacitors,resistors with
greater ratings.since size is the restriction.

Answer / ln sharma

as per international standard.

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