why can't we use 5-20mA standard or some other instead of 4-
20mA?
- 6 Answers
- 13224 Views
- Emerson, I also Faced
- E-Mail Answers
Answer Posted / selvam
4 - 20 ma is used because one resion is that control system
like DCS AND PLC will accept (1 - 5vdc)only for that resion
by connection 250 ohm resistand accross with ( 4 - 20 ma)
we can get ( 1 to 5 vdc) (1vdc=4ma and 5vdc=20ma) this is
as per ohms law ,V=IR
IF V=4ma*250ohm=1vdc
20ma*250ohm=5vdc
(4 - 20)ma is linear with(0 -100%) and the output will get
linear from 4ma,
| Is This Answer Correct ? | 3 Yes | 0 No |
Post New Answer View All Answers
Hi Friends i need Electronics&Instrumentation Engg question papers for BARC written test by coming 20th May 2008 pls post ur use full info to kkumarei@gmail.com. Or for suggestions pls give one missed call to 9962122264
What should be the main consideration while starting the Rotating compressor when we dont know the cut in and the cut off pressure setting of the pressure switch
send me HPCL paper
which type inter lock use in petrochemical refinery,and oil & gas?
what is instrument philosophy
What is compensation for flow ? Why we use compensation ? What are the factors of different compensation ? We not use then what problems may happen ?
How a conductivity sensor & analyzer work at boiler, whats the principle & science is beyond this,How conductivity sensor sence & convert signal & move toward analyzer & analyzer show reading in percent? also what is temperature compensate option in conductivity analyzer
What is furnace draft control?
Explain the burnout feature.
How hart protocol can be connected with control valves?
please send me the inteview questions in IOCL
Senior engineer's please help me, what is Loop Checking and Loop test? and write difference also? soon urgent
How to Calibrate Temperature Switch in field
What is stripper & spilitter ? Diffrence in this.?
Calculate the maximum pressure drop that can be allowed to occur across a control valve, so that we can prevent cavitation / flashing from occurring. Use the following formula: Δ P allow = Km (P1 – PvapourA) where, Δ P allow - the maximum allowable differential pressure for sizing purposes, or terminal pressure drop; Km- the valve recovery coefficient from the manufacturer’s catalogue; P1 - absolute inlet fluid pressure; PvapourA - absolute fluid vapour pressure at the inlet temperature; Use Atmospheric pressure = 101.3 kPa, P1 = 1200 kPa(g), PvapourA = 4 kPa, KM = 0.72
