why can't we use 5-20mA standard or some other instead of 4-
20mA?
Answers were Sorted based on User's Feedback
Answer / mohammed abbas
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 ? | 37 Yes | 2 No |
Answer / sivasankar
The base range of the electronic transmitter out put is 0
to 16 mA. but during measuring through a series DC volt
connection (24VDC)the negative reading could not be
justified either the result is wrong polarity or the actual
negative reading below Zero value. So international
accridation has decided to elevate the zero value from 0 mA
to 4mA and straight way increased span value also from 16mA
to 20mA.(as an equal increment in 5 step 0%,25%,50%,75% and
100% of out put). Generally the electronic sensor base
output reading trimmed with 2.99 to 3.22 mA from
manufacturer. if the sensor is in good condition it will
show the base reading. 5 to 20 mA reading is not accepted
in industry so far.
Is This Answer Correct ? | 20 Yes | 14 No |
Answer / 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 |
Answer / sutharani.a
The electronic instrument using only dc power supply. so
using the standed value of 4-20mA, because 0-16mA is the
standared deviation elctronic meters. 0 value is not
pricise value so zero insted of four and 16 insted of 20.so
we are use to 4-20mA normal.
Is This Answer Correct ? | 2 Yes | 2 No |
Answer / naveed ahmad
due to linearity, we can't use 5-20ma because in case of 5-
20mA our 25%,50% and 75% 'll not linear.
Is This Answer Correct ? | 0 Yes | 2 No |
Hi, I'd like to know the purpose of MOS (maintenance override switch). At site, these switches are installed in a stanchion with the transmitter (connected to ESD). thank you.
3 Answers Adani, Adani Wilmar,
what is vfd(variable frequency drive)?type of vfd.
Pls.could any one Clarify the following with an example. 1.At What condition Close on Rise and Close on Fall Pressure Switch contacts are used. 2.If Pressure is abnormal as per set pressure,if connecting Terminal of pressure switch breaks,how the voltage extends to Relay base. 3.Are these contacts come under fail safe philasaphy.
Why we used cage in control valve?
Can anyone send most commonly asked interview question in Oil & Gas industry
what is commisioning procedure,2)what is is the main work in commisioning in the field tx to dcs, plz send me detail
Explain level troll principle & interface level measurement.
i want to measure temp of hot sand(welding flux) in closed chamber(around 150 deg C).Which is better thermocouple or thermometer?
what is the diffrence between mmwc and kg/cm2 for pressure measurment when we are using mmwc and when kg/cm2 and why????? ?? what is the reason
19 Answers Ecoboard, Jindal, Sepco,
what is the difference between(Flame proof/Explosion proof)& Fire proof instruments.Both are same or different & if different in which way because the transmitter which have approved ATEX flame proof enclouser but it use PTPE O ring & PTFE Head Gasket,so its (fire safe/fire proof)????????
How to Calibrate Interface Level Troll in field
what is meaning of software redundency and hardware redundency?