Why the industry's standard current standards are from 4mA to
20mA,not from 0mA or any other range?
Answers were Sorted based on User's Feedback
Answer / fidelis
This is for the purpose of identifying a fault either in
the instrument or in the control loop. If there is a fault
in an instrument, the reading on that instrument will be
zero as when the transmitter is not reading any data due to
maybe a broken loop, so one may not be able to tell what
the problem is. But with the 4-20mA standard, it will be
simple to tell if the transmiter is faulty or not. This
makes trouble-shooting easy.
Is This Answer Correct ? | 28 Yes | 0 No |
Answer / pramod
if we are using a transmitter there is defenite distance is
specified for it. if we dont have at least 4mA the signals
will be loss for the max. defined distance.
The mA is chosen because it will not make more electrical
hazardness in the field instead of that if micro A is used
loss of signal may occure.
By taking base as 4mA by persentage means 20 mA set as max
value
Is This Answer Correct ? | 5 Yes | 12 No |
what type of cables are used for f&G systems and detectors, what is the standard colour?
i have 80cm water tank.how can i use DPT as level mesurment.pls give specs for that..? We have air comp.from that moisture comeout to one tank.i want to mesure level of water in that tank and then after operat one sov to dicharge water after high level.
How to isolate a DPT from line in the condition that process must not be disturbed,and process is also critical and no bypass is available.?
How to calibrate the flow transmitter
What is mean by Adapter block and net block?
what is the difference between plc and pc?
key phaser where is use and work
What safety precautions you will adopt to work on Steam service control valve?
which type of filter gives the constant phase characteristics?
What are SMART insuments?
Why humidity limit is 30 to 55 % for raw material storage?
Guy's need your support,I want to measure closed tank level which is under vacuum -630mmHg using DP Transmitter, tank fluid density 1.38, Tank height is 7ft