Process Control and Instrumentation problems
- 1. A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same
Options- A. temperature measuring range (- 40°C to 450°C).
- B. accuracy (± 1% of span).
- C. speed of response.
- D. all a, b & c. Discuss
Correct Answer: all a, b & c.
- 2. Suppose that the gain, time constant and dead time of a process with the following transfer function:Gc(s) = 10 exp( - 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as
Options- A. 8, 0.6, 0.08
- B. 12, 0.6, 0.12
- C. 8, 0.6, 0.12
- D. 12, 0.4, 0.08 Discuss
Correct Answer: 12, 0.6, 0.12
- 3. For a feed back control system to be stable, the
Options- A. roots of the characteristic equation should be real.
- B. poles of the closed loop transfer function should lie in the left half of the complex plane.
- C. Bode plots of the corresponding open loop transfer function should monotoni-cally decrease.
- D. poles of the closed loop transfer function should lie in the right half of the complex plane. Discuss
Correct Answer: poles of the closed loop transfer function should lie in the left half of the complex plane.
- 4. __________ controller has the maximum stabilising time.
Options- A. P
- B. PD
- C. PI
- D. PID Discuss
Correct Answer: PI
- 5. __________ type of element is normally not used in the bimetallic thermometers.
Options- A. Flat spiral
- B. Bourdon tube
- C. Single helix
- D. Multiple helix Discuss
Correct Answer: Bourdon tube
- 6. Flow rate of sludge is not measured by a/an
Options- A. orificemeter
- B. open weir
- C. kennison nozzle
- D. both(b)&(c) Discuss
Correct Answer: both(b)&(c)
- 7. Which of the following is not a second order instrument?
Options- A. Mercury in glass thermometer with covering.
- B. Bare mercury in glass thermometer.
- C. Pressure gauge with one bellow, two tubes and a tank.
- D. None of these. Discuss
Correct Answer: Bare mercury in glass thermometer.
- 8. Thermal wells used in temperature measurements should have
Options- A. very thick walls.
- B. low emissivity.
- C. polished surface.
- D. high transmissivity of radiation. Discuss
Correct Answer: high transmissivity of radiation.
- 9. In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.
Options- A. load
- B. manipulated
- C. controlled
- D. none of these Discuss
Correct Answer: load
- 10. Out of the following themocouple wire insulating material, the highest temperature rating is for
Options- A. teflon
- B. ceramic fibre
- C. asbestos
- D. fibre glass Discuss
Correct Answer: ceramic fibre
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