Answer / chandrasekaran.n

This is only concept of live zero & dead zero.live zero is
4ma.because if any faulty in your sensor are signal
transmitting field cable are your power source fuse failure
you can easily find out that live zero concept.

Answer / shazly

it gives us the ability for knowing if there is cuttig in
the wire.but if we use 0-20 if there is a cutting in the
wire it will indicate also 0 which we have and i will not
give us any idea if there is cutting or not

Answer / boobalan

4-20mA is used to identify the process zero.

Answer / dean hardage

The use of a current loop is to allow operation of the
intrument over a relatively long distance. The use of 4-20
milliaps make possible the use of a 'live' zero and
provides for an indication of a wire break. It also allows
for loop powered instruments to function. At zero current,
the electronics of a loop powered transmitter would not
work and the sensor would be effectively dead.

Answer / s.chandra mowli

for example take a temperature process
0 degree it must indicate -0 ma
suppose if there is any fault in the circuit then for any slight increase in temperature it indicates only zero
in order to differentiate the malfunction of instrument
we use live zero and dead zero
the instrument is biased to 4 ma to indicate the proper function of the the instrument that is Live zero
if it indicates 0 then is a malfunction in instrument that is Dead Zero

Answer / m.mohan

4 MA

LIVE ZERO DEAD ZERO CONCEPT

20MA

ELECTRICALLY UPTO 20MA THERE IS NO CREATING A SPARK
IN THE TIME OF SHORTED LOOP.ALSO CURRENT TRAVELLING LONG
DISTANCE WITHOUT NO DROP.(UPTO 1500m)

the main purpose for choosing 4to 20ma easily convert to
voltage to add 250 ohms resistance with the help of ohm's
law

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