Follow Our FB Page << >> for Daily Laughter. We Post Funny, Viral, Comedy Videos, Memes, Vines...

why 4-20 mA in covection system?

Answers were Sorted based on User's Feedback

why 4-20 mA in covection system?..

Answer / ranganadh

Long distance communication mA signal is preferable than
mV, V signals to avoid noise. It cann't be predictable with
0 mA, whether the loop was broken or the signal itself. So
to avoid loop break problems we consider 4mA as the lowest
signal. Moreover, it is recommended to put a 250 ohms
resistor at the input terminals of the instrument to get
1VDC for 4mA and 5 VDC for the 20mA and further these
signals will be amplified by instrumentation amplifier in
the instrument circuit.

Is This Answer Correct ?    8 Yes 2 No

why 4-20 mA in covection system?..

Answer / jazz

4-20 mA signal differentiates live process 0% with 4mA
signal with a wire break (0 mA), current is also used for
transmission because even if your receiver or PLC/DCS card
is far away current signal sent proportionately by the
transmitter will be received as the same current at the
receiver/PLC/DCS card, although it is converted as a voltage
signal (1 to 5 VDC) by a 250ohm resistor, since
micro-processor process signals in voltage levels.

Is This Answer Correct ?    1 Yes 0 No

why 4-20 mA in covection system?..

Answer / jagdish

bcoz span 16 is suitable for coding in plc logic and its use
for live zero detection and as well as plc operated at 1 to
5 volt so if 250ohm Resistance is there ,so, 4 to 20mA is

Is This Answer Correct ?    1 Yes 0 No

Post New Answer

More Instrumentation Interview Questions

What is difference between reset and initialization in system.

1 Answers   Marafiq,

How it the difference between force balance system and dispalacement balance system?

0 Answers  

Explain PID controller tuning & any one method used for it.

1 Answers   L&T, Oil India,

What is the diffrence between ff tx and non ff tx

0 Answers   Jindal, Rosemount,

what is meant by nuclear power plant?

1 Answers  

Explain level troll principle & interface level measurement.

1 Answers   ADMA OPCO,

How many are the types of instrument cables in terms of No. of pair.

0 Answers   CCIE, Samsung,

how to control motor load with rpm or vfd

1 Answers  

what is the formula for changing Range of Transmitter from X mmwc to some Y mmwc with respect to DCS NCMH flow range from x NCMH to y NCMH?

1 Answers   HCL,

Which is the best field foundation bus. ( FF ) Yokogawa, Honeywell or others ?

0 Answers   GNFC,

what is the use of glycol filling in seal pot (or) condensate pot in instrument impluse line?

7 Answers  

You are looking at the RS-485-side of an RS-232/RS-485 converter and the power supply voltage for the converter is +5V. Under idle conditions (no transmission), and assuming you have enabled the RS-485 output: what would you expect at: (a) Output A measured against output B (b) Output A measured against ground (c) Output B measured against ground

1 Answers   EIT,

  • Civil Engineering Interview Questions Civil Engineering (5076)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4445)
  • Electrical Engineering Interview Questions Electrical Engineering (16606)
  • Electronics Communications Interview Questions Electronics Communications (3915)
  • Chemical Engineering Interview Questions Chemical Engineering (1092)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (214)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (258)
  • Instrumentation Interview Questions Instrumentation (2992)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (123)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (0)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1378)