Answer / vinoth

the destination of any signal will be a Controller.
Take DCS, its input supply will be 1-5V.
from instruments, across a 250ohm resistor, the value will
reach DCS as desired 1-5V.

expl:
say 4ma is the output of transmitter.
V=IR,
V=4ma * 250 ohm
V= 1V,
say 20ma,
V=20ma*250ohm
V=5V.

Answer / dhanabalan

It is where the linearity is maintained (4-20 mA Signal).

Answer / t.naveen babu

The reasons for the 4-20 mA standard (and, before it, the
10-50 mA standard) have a lot to do with the original 3-15
psi/20-100 kPa air
signal. The origin of the suppressed or "live" zero in the
pneumatic system was two-fold - if you want to reduce a
passive pneumatic signal quickly, you need to maintain some
differential between the pressure and the "sink" - in this
case, atmospheric air. The basic characteristic of a
flapper-nozzle assembly also has a bit to do with it -
the "linear" range of the flapper pressure is about 3 - 15
psi for a 20 psi supply. Next question - why a 20psi
supply? Anyone else remember 6-30 psi equipment for
final actuators needing a bit more grunt??

The original electronic instruments were direct imitations
of the pneumatic systems with bellows replaced by magnet-
coil assemblies. The first I came across were used in a
geothermal power project (1958 vintage)where the pressure
at the power station was controlled by manipulating valves
in the steam field 1 1/2 miles or so away. The flapper-
nozzle was replaced by a
contact moving between positive and negative terminals - I
guess a bity of mains hum in the amplifier kept it
jittering. In the mid-70's Foxboro produced a range of
pressure transmitters using the magnetic principle which
used the same basic mechanism as their pneumatic equipment -
but the size of the coils made the assemblies a lot
bigger ...

Answer / abhishek

this 3-15 psi later used in electronic signal as 4-20mA. 4mA
used as live Zero , & 20mA is current so
20mA*24V=480mWatt. this power if we increase any signal
wire can cause such type of arc that can cause Fire.

Answer / ahmad

1- Any electronic circuit having its error, here Ico=3.85 ma(aprox=4 ma). that is why we do start from 4 ma.
2- it is also convertable to 1-5 volt, with precision resistance of 250 ohms.

the square root type transmitter r used to which applications

4 Answers   Roche,

without color coding, without nameplate, without multimeter how can you find the type of thermocouple???

1 Answers   Sabic,

Instrument QA/Qc what is the project quality plan?conduit inspection RFI. which documents attache with package?

0 Answers  

What are the instrumental diagram of valve.

2 Answers   Karnataka Power,

How to Calibrate Level Troll in field

0 Answers  

what is the function of a diaphragm?

1 Answers  

Generally in which location ( JB or IO card or DCS) the thermocouple compensation is done.Also where they measure the atmosphere temp ( for compensation) in JB OR DCS panel? How they compensating that atmosphere temp? is any circuit for that ( like in rtd wheatstone bridge)?

3 Answers  

how to draw a flowchart for swapping two numbers using bit wise operators?

1 Answers  

what are the use of belew gear in general ??

0 Answers  

can you give some devices that measure directly the mass flow rate.

1 Answers   Takreer,

HELLO FRENDS ,, I M IN THE MIDST OF TROUBLE .. JUST LITTLE HELP ME... SUPPOSE ,, I HAVE A CLOSE VESSELE TANK ( HEXANE MEDIA ) ,, I M USING ROSEMOUNT 2051 DPT FOR LEVEL APPLICATION .. ITS CALIBRATE RANGE IS.. . 0 TO 950 MMH20 ..I DID CALIBRATED DPT WITHOUT REMOVING IMPULSE LINE OF HIGH AND LOW TAPPING.. & WITHOUT DISTURB 3 WAY MANIFOLD..!!! BUT ,,, DURING CALIBRATION I SELECT RANGE BY HART LRV IS 900 MMH20 & URV IS 1300 MMH20 ,, BUT ,TANK LEVEL SOMETIMES 100 % AT 1100 MMH20 , SOMETIMES 1300 MMH20 ..IN THIS CONDITION .. WHOLE LOOP FAILED ,, MAIN THING IS THAT ,, HOW TO CUSTOME RANGE SELECT ?? AND IF I USED RANGE OVER THE ORIGINAL CALIBRATE RANGE ,,,THEN WHAT ERROR WILL BE COME ??? HOW TO ZERO CALIBRATION OF DPT... HOW TO ZERO TRIM BY MANIFOLD ?? AND FOR TANK LEVEL PURPOSE ... WHICH UNIT I CAN USE ??? IS THERE ANY CALCULATION OR CALIBRATION .. IF YEH .. THEN PLZ JUST GIVE ME CALIBRATION STEPS FOR DPT.. THANKS YOURSSSSSSS

1 Answers   Torrent Pharma,

what is meant by Hydroelectric powerplant?

0 Answers