Question { 9052 }

1. How many output signals do wew have in process control?
2. Could you write down the names of the pre-commissioning
and commissioning stage test instruments and explain them
(more than 5 items)?
3. What is the first step to commission a transmitter on
service?
4. What is RTD?
5. Find the output value in MA of a temperature transmitter
(RTD Type) at 120degree celius?
6. What is the O/P signal of a pneumatic transmitter?
7. What is the O/P signal of an elctronic transmitter?
8. What is the close loop and open loon?

Answer

1. Two output signals are used in process control -
analogue and digital.
2. RTD - Resistance Temperature Detector for temperature
measurement upto 600°C.
3. O/P signal for pneumatic transmitter is pneumatic signal
3 - 15 psi
4. O/P signal for electronic transmitter is electrical
signal 4 - 20 mA, 1 - 5 volt.
5. Close loop having sensor, transmitter, controller, and
controlling element (like control valve, on off valve,
damper, servo motor). Open loop does not have controlling
element. open loop is used for only indication in control
system.