Why we use 4 to 20 mA, (This is International Standard)
instaed of this can we use 4-16, or 4-24 or 3- 15 or any
other range

Answer Posted / richard marks

the 4mA zero is termed a "live zero". If 0mA was the zero
point there would be no way of telling if the transducer
was reading zero or in a fault condition eg. an open loop.
with a 4mA zero an open loop would drive the indicator eg.
a recorder into a minus figure (-25%). The 4 - 20mA scale
is to give a calibration points for 0-25-50-75-100%.
Because the start point is 4 the steps are 4mA.

Is This Answer Correct ?    14 Yes 6 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

any one can send me instrumentation previous interview papers? I prepare for MNC Company Interviews? my mail id- Rakesh.Golla@dodsaldxb.ae , and another mail rakesh.gvk@gmail.com

1523


What is the start up procedure of desalter

3061


How to Calibrate Interface Level Troll in field

791


What is super thermocoupal?

1705


any body please send me the old question papers of ongc test.

1685






field bus transmitter calibration procedure tell me

1366


can we create an interrupt in plc through scada?

1908


I installed the smartplant instrument v8, but can not be opened, that always said: "INTools 2007 hardlock no found". So Could you help me how to do for that?

1649


I wnat to practice more online type questions .so will you show them me to take a practice test?

930


whats the abbreviation of IOP? is it instrument of power or input open problem?

673


full process of gas turbin?

1571


Dear Friends, we are planning to design Power distribution and Fiber optic in the same cabinet.Like Front side Fiber optic and Rear side Power distribution.Is it any possibility of problem occurs like interference etc? Your answer is highly appreciate.

1753


Explain the working of an electronic level troll.

607


HI, can anybody give details about GAS TREATMENT PLANT CONSTRUCTION,as INSTRUMENTATION ENGINEER what are the responsibilites.what are the instruments mainly instrumentation engineer will deal with

1625


while i check zero check for dp flow transmitter some fluctuating came (0 to 458 kg/h) what is the reason?

1356