Answer Posted / chiru mudra...
There r 2 reasons for this.....
1) All micro controllers, plc, dcs etc., are operated with 1
to 5 volts supply.( Ex: 1v=low, 5v=high).
At the input & output of these devices we use 250 ohm
resistor for converting this 4-20mA to 1-5volts.
ie; 4mA*250 ohms = 1Volt
20mA*250ohms = 5Volts.......
2) If we use this range from 1mA to some range there is a
problem with that.
which is, in industries we use bunch of cables together from
field to control room and vice verse. Due to this there is
some signal distortion in the other cables due to magnetic
induction (electro magnetic induction effect in the other
cables). ie, 1-2 mA current will generate in the unactivated
cables which may cause the mall fn in the total industry.
Ex: 1mA = 0% valve open
2mA = 10% valve open
3mA = 20% valve open.... etc.
| Is This Answer Correct ? | 27 Yes | 5 No |
Post New Answer View All Answers
any body who gone thru recent iocl interview.INSTRUMENTATION questions. I need.
use of split range ? where it is used ? in which control loop it is used ?
What is the Working principle of Dozing valve?
can any send me a forbes marshall dtron 316 manual
please any body have most important data for study for saudi aramco test of instrument QC thanks email shahnaveedullah@gmail.com
send me model hpcl questions pleas..........my mail id mohideen.dharvesh@gmail.com
sir i m preparing for BARC but i am not getting any papers to prepare for this exam so please send me some sample papers to my i.d for the preparation of barc.
please tell no. & add. of consultancy who recruit me in power plant as instrumen engg. present i m working in power plant as ass.t instrument engg. thanku mahesh 09226562826
this site is owned by an nonsense
Can any one send me IOCL instrumentation question papers.. i dont know the pattern of the questions and what to prepare can any one help me on this .. my email id is anwarnishil@gmail.com
please send data bank of quetions answers on analytical instrumentation.
hye SAM acn u send your e mail id, so that i can solve my query through e mail?
sir, i preparing hpcl,ongc,barc,hal exams(instrumentation engg)pls send a placement papers
please send me some question papers of HPCL aptitude test ?? please send it to bipinb.28@gmail.com ...
hi i am eswar i want to know the instrumentation interview questations for eil(engineers india ltd) i have applied for engineer post in eil please help in this.my mail id eswar310@gmail.com
