Process Control and Instrumentation — MCQs – EE

1. The main objective of process control is to:
(A) Increase process disturbances
(B) Maintain process variables at desired values
(C) Eliminate sensors and transducers
(D) Maximize process noise

2. A process variable is:
(A) A fixed parameter
(B) A measurable quantity of the process
(C) A control algorithm
(D) A controller output

3. The set point in process control refers to:
(A) The measured process value
(B) The desired value of the process variable
(C) The controller output
(D) The process disturbance

4. A controller compares the measured value with the set point to produce:
(A) Error signal
(B) Process noise
(C) Feedback delay
(D) Frequency response

5. The final control element in a process control loop is usually a:
(A) Sensor
(B) Actuator or control valve
(C) Transducer
(D) Display unit

6. The open-loop control system operates:
(A) Without feedback
(B) With continuous feedback
(C) Only during disturbances
(D) At steady state only

7. The closed-loop control system operates:
(A) Without sensors
(B) Using feedback
(C) Without actuators
(D) Only manually

8. The P-controller acts on:
(A) Integral of error
(B) Derivative of error
(C) Instantaneous error
(D) Sum of past errors

9. The I-controller helps to:
(A) Reduce steady-state error
(B) Increase transient overshoot
(C) Reduce system gain
(D) Delay system response

10. The D-controller improves:
(A) Steady-state response
(B) Transient response and stability
(C) System gain
(D) Process delay

11. The combination of P, I, and D actions is known as:
(A) LQR controller
(B) PID controller
(C) Kalman filter
(D) Open-loop system

12. The main disadvantage of a P-only controller is:
(A) High steady-state error
(B) Complex design
(C) Instability
(D) High control cost

13. The control valve is an example of:
(A) Measuring device
(B) Final control element
(C) Sensor
(D) Controller

14. A transmitter in a process control loop:
(A) Converts sensor signal into a standardized form
(B) Acts as a controller
(C) Generates error signal
(D) Controls the actuator

15. The common signal standard for industrial transmitters is:
(A) 0–5 V
(B) 4–20 mA
(C) 0–10 V
(D) 1–10 mA

16. A thermocouple measures:
(A) Pressure
(B) Temperature
(C) Flow rate
(D) Level

17. The RTD (Resistance Temperature Detector) works on:
(A) Change in resistance with temperature
(B) Change in capacitance
(C) Change in inductance
(D) Change in frequency

18. A strain gauge measures:
(A) Force or pressure via deformation
(B) Temperature
(C) Flow
(D) Level

19. A Bourdon tube is used to measure:
(A) Temperature
(B) Pressure
(C) Flow
(D) Level

20. The rotameter is used for measuring:
(A) Temperature
(B) Flow rate
(C) Pressure
(D) Level

21. The orifice plate is used to measure:
(A) Flow rate
(B) Temperature
(C) Pressure
(D) Level

22. The tacho-generator measures:
(A) Speed
(B) Position
(C) Torque
(D) Displacement

23. The LVDT (Linear Variable Differential Transformer) is used to measure:
(A) Pressure
(B) Displacement
(C) Temperature
(D) Flow

24. The process gain in a control system refers to:
(A) Ratio of output change to input change
(B) Frequency response
(C) Time delay
(D) System order

25. The dead time in process control represents:
(A) Delay between input change and system response
(B) Control gain
(C) Noise level
(D) Sampling frequency

26. The time constant of a process is a measure of:
(A) System speed of response
(B) Steady-state gain
(C) Noise amplitude
(D) Process disturbance

27. The Bode plot of a process control system shows:
(A) Frequency response
(B) Step response
(C) Time-domain response
(D) Phase margin only

28. A servo system is designed to:
(A) Track reference inputs
(B) Reduce steady-state error
(C) Respond to disturbances
(D) All of the above

29. A process disturbance is:
(A) An unwanted change affecting process output
(B) A reference signal
(C) A sensor signal
(D) Controller output

30. The Ziegler–Nichols method is used for:
(A) PID tuning
(B) Root locus
(C) Stability analysis
(D) Frequency domain design

31. The cascade control system uses:
(A) Two or more controllers in series
(B) Only one feedback loop
(C) No feedback
(D) Open-loop design

32. The ratio control system maintains:
(A) Fixed ratio between two process variables
(B) Constant flow rate
(C) Constant pressure
(D) Zero steady-state error

33. The feedforward control acts:
(A) Before the disturbance affects the process
(B) After the disturbance
(C) Without sensors
(D) With open-loop only

34. The feedback control acts:
(A) After the process output changes
(B) Before the disturbance
(C) Without measurements
(D) Without controllers

35. The SCADA system stands for:
(A) Supervisory Control and Data Acquisition
(B) System Control and Direct Automation
(C) Sequential Control and Data Access
(D) Signal Control and Data Acquisition

36. The PLC (Programmable Logic Controller) is used for:
(A) Industrial automation and process control
(B) Communication systems
(C) Frequency tuning
(D) Power generation only

37. The HMI (Human Machine Interface) provides:
(A) Interface between operator and control system
(B) Signal conditioning
(C) Process measurement
(D) Controller tuning

38. The sensor drift refers to:
(A) Gradual change in sensor output over time
(B) Sudden failure
(C) Constant offset
(D) Signal amplification

39. The rangeability of an instrument is:
(A) Ratio of maximum to minimum measurable value
(B) Accuracy percentage
(C) Sensitivity of the device
(D) System response time

40. The smart transmitter includes:
(A) Microprocessor-based signal processing
(B) Mechanical output only
(C) Pneumatic operation
(D) Manual calibration