in instrumentation why we are using 4-20mA , why not
voltage ? if somebody design a instrument which works on
voltage then can we use that instrument?
Answer Posted / pradeep patil
Current 4-20 mA is prefered than voltage because:--
1)current signal can be carried to long distance without
drop in signal strength.
2)Less Electro Magnetic Interference effect in current
signal
3)no short crcuit spark happpens when signal cable
accidently short each other.
If your controller works on voltage (1-5 vdc) then 4-20 mA
can be easily converted in to voltage after connecting 250
ohm resistance accross signal cable as per ohms law.
Is This Answer Correct ? | 14 Yes | 0 No |
Post New Answer View All Answers
What are different types of valves?
Can any one tell me what type of question asked for instrumentation and control interview panel??? pls mail ramashankar.goel@gmail.com
i have used level transmitter in starch cooking preparation tank. tank total height 2mtr.sometime LT display shows some error value when tank is fully empty and diaphragm side i already checked okay no problem in diaphragm area. field cable checked 24volt and mA shows correct value while tank empty mA is 4mA. 4mA i needed that 0% but display showing 10% or 15% percentage values are varying continously please give any good solution for me.....
Where is wet leg is used?
i want formula for flow control.am doing project in flow control using orifice . i know value of the flow level(Q) . upstream(p1) pressure, orifice diameter(Do) , pipe diameter(Di) and oil viscosity(Vi) how can i calculate downstream pressure
What is first echo & echo window in radar type level transmitter?
What is mean by analytical instrumentation?
all questions related to instrument technician in any offshore oil and gas company.
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
In bently nevada vibration monitoring system,what is the reason to maintain the Resistance of the probe + extension cable equal to 95 ohm? If possible explain the basic principle of measurement with detail electronic circuits.
can any one tell me when ongc placement test and its forms is available????/ pls tell me if u know
Full form of KKS when use DCS.
What are primary elements of measuring pressure? Which type of pressure can be measured by these elements?
Explain the difference between plc and cnc?
hi my name is rakesh patel i just complited my be in instrumentation & control now i am going to working as a validation engineer in a poject department so what is a scope in a future as a validation engginer ? what line is good for me can any bady give me complete solution please? your regard rakesh patel