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 / nilesh karpe
Rajesh & BM has ansered 1 to 12 questions:
13.first check the stroke of the valve.ie. fully open &
then full close(for checking smooth operation).
ZERO CALLIBRATION:
at full close see the demand of i/p is 4MA.& output for
this is 0.2 KG/cm2. if not adjust through ZERO pot in i/p.
SPAN CALLLIBRATION:
fully open the valve.at this time the dmd of i/p should
20MA.at this time o/p supply air should 1KG/CM2.if not
adjust the span pot in i/p.
REPEAT THE ABOVE STEPS IN TILL ZERO & SPAN READINGS
MATCH.CHECHK INTERMIDIATE POSITIONS i.e. for dmd signal of
4,8,12,16& 20MA.FOR LINEARITY CHACKING.
| Is This Answer Correct ? | 23 Yes | 0 No |
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