why we use 4-20 mA to do calibration of the instruments.why
we cant use 0-20 mA?
Answer Posted / kashif mahmood
1) This is called the live zero or elevated zero concept.
It makes us differentiate between the signal failure and
the zero reading of the transmitter. Let's say, LRV=0 mA
and the instrument cable is cut. How can somebody ascertain
that this is process zero(LRV) and not the cable fault.
whereas if LRV = 4mA and the cable is cut, the current
through the loop would be 0mA and one can find out that
this is the cable fault.
2) its the lowest linear possible range with minimum power
consumption.
| Is This Answer Correct ? | 122 Yes | 8 No |
Post New Answer View All Answers
If fire would be inside the plant which fire detector is to detected the fire.
please tel me the calibration of pneumatic controler.
i have been asked by QAFCO to appear for interview for thy post of Instrument Designer(INTOOLS)..i m engineering graduate with 5 years exp. in design engineering.Will this job profile suit me??i need all ur help n suggestions for thy same?
hey any one got the papers of SAIL and HPCL plz do help me by posting them to my mail ID's naren07_87@yaho.co.in, surenarendra@gmail.com
how u calibrate pneumatic n motorized c/v?
Explain the key components of control loop?
what is interlock system and why we use of this?
Explain the mechanism behind the turbine meter.
i have done DAE in Instrumentation and Process Control. i have applied for an apprentice training in chemical company after three day my interview will be conduct but i need more information about industrial process control and controller. my e mail is imran_dilsetu@yahoo.com please tell me interview question relative to instrumentation ?
How d.p. Transmitter can be applied to close tank?
How to convert Differential pressure to flow in TPH
hi sir yhis is zahid ali i am preparing for the jspl at oct.4.please send me the recently updated sample paper.
what are the diff. in servo and regulatory control?
what is the advantage of submersible level transmitter compare to ultrasonic level transmitter?
Define the terms Accuracy, precission, Spam, process tolerance while doing calibration of an instrument? Explaini with an example?