Answer / bunny

Suppose the range of process variable is
(0-150)PSI.So when the input is zero,the value in
instrument,say a transmiter connected to measure the
pressure,will shows 4mA.This is live zero.i.e,even if the
input is zero,output has some value.
Lets assume the instrument is faulty or the
power supply to the instrument is cuts off.Then it will
show zero reading.This is called dead zero.i.e,when the
instrument is faulty,it will shows the real zero value.

Answer / devendra_kushwaha27

Live Zero means 4MA
Dead Zero means below 4 MA

Answer / inzamam

When the working instrument shows zero as its output ....it is called as live zero........

When the instrument fails , thereby showing zero as their output , it is called as dead zero .

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