1. What means HART communicator / where it is used /
how to use it?
2. Types of Thermocouples and its temperature ranges /
output of thermocouple?
3. Types of RTDs and its temperature ranges / output
of RTD?
4. Idea about Temperature Transmitters?
5. Difference between Analog and Digital signals?
6. Difference between “2 wire” and “4 wire” system /
instruments?
7. Difference between “Potential” and “Potential free”
contact?
8. Types of flow meters / transmitters?
9. Types of level transmitters?
10. Difference between “Power/Control” cable
and “Instrument” cable?
11. What means “shield” and “screen” in cables / how it
is useful?
12. Draw a schematic of closed loop circuit of flow /
level / pressure / temperature?
13. Idea about calibration of Control valve /
positioned / I/P?
14. How to bypass a digital/analog signal in PLC/DCS by
hardwire and software?



Answer Posted / rajesh

1.HART is Communication Protocal.it is used to Communicate
the Field Instruments for measuring and Calibrating purpose
2.K Type : 0-1370 degrees
J Type: 0-700 degress
B Type: 200 -1800 deggress
R type: 200 - 2450 degrees
Output of Thermocouple is DC Potential (milli volts)
3.Platimum RTD :PT-100 Range:-270 to 600 degress
Output of RTD is Resistance
4.Temparaure tranmitters
it will receive the sinal from sensor (thermocouple /
RTD) and this signal will convets to 4-20mA or 0-20mA
5.Analog Signal is contioues measuring signal ie it's
measuring Range is 0 to 100%
Digital signal is a Binary form ie. Its state is Either
High (1) or Low(0)
6.in 4 wire Tranmitter Have Seperate exitation Supply is
for its Operation and Output taken for seperately.if the
Tranmitter Elecronic Cercuit is drawing More than 4 ma of
current then it will apply the 4 wire scheme.
in 2 wire Tranmitter working supply and its output is
taken in same cable.ie its working supply is lessthan 4 ma.

Is This Answer Correct ?    63 Yes 6 No



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