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?
Answers were Sorted based on User's Feedback
Answer / bnp
because there is voltage drop as per the length of conducting wire. but current has no drop
| Is This Answer Correct ? | 16 Yes | 0 No |
Answer / 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 |
Answer / himanshu
4-20 mamps is best choice because interference level is
minimum in current application where as in 0-10 V it is
comparatively high.Thus in using 4-20 mamps signal is
distortionless.
| Is This Answer Correct ? | 6 Yes | 1 No |
Answer / b0nz0
Most of the above answers are valid, but none have
mentioned security. If a current loop is broken then the
current will fall to 0.
| Is This Answer Correct ? | 2 Yes | 0 No |
Answer / yogi40
if we use voltage there there is noise interpretation
where as in current it wont happen
and current supports 2 wire connection,voltage doesnt
there will be drop in voltage when its feedback in current
such loss is very less
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / manuraj singh sengar
no, because voltage makes fluctuation & current remains
constant.
| Is This Answer Correct ? | 0 Yes | 12 No |
How much flow is passing through 6 inch line? There are no gauge, no any transmitters in line.
why do we use 4-20mA as o/p and why don't use 0-20mA or 5- 21mA?
Meaning of the following a. IOP- Manimum; b. IOP- Maximu,;
What is the differaence between PLC and DCS?
Basic working principle of control valves
How to calibration coriolis flow meter?
what do u mean by compensating?in power plant where are compensating done?how level , flow compensated?
Difference between ultrasonic flow meter and radar type flow meter
2 Answers Dodsal, Qatar Petroleums,
what is the daily job of an instrument commissioning supervisor
what is intrinscily safe system and where we use?
What is three element in drum level?
What is shielding effect?
0 Answers Process Control Technologies,
Civil Engineering (5086)
Mechanical Engineering (4453)
Electrical Engineering (16638)
Electronics Communications (3918)
Chemical Engineering (1095)
Aeronautical Engineering (239)
Bio Engineering (96)
Metallurgy (361)
Industrial Engineering (259)
Instrumentation (3014)
Automobile Engineering (332)
Mechatronics Engineering (97)
Marine Engineering (124)
Power Plant Engineering (172)
Textile Engineering (575)
Production Engineering (25)
Satellite Systems Engineering (106)
Engineering AllOther (1379)