Process Control Questions & Answers
1. With a proportional-only controller, if measurement rules set point, the output will be:
a. 0
b. 100 percent
c. 50 percent
d. Impossible to define
Answer: c
2. If in a proportional-plus-integral controller measurements away from the set point for a long period, the controller’s output will be:
a. 0
b. Unknown
c. 0
d. 100 percent
Answer: a
3. In the modem controller, derivative action is applied only to the:
a. Error
b. Measurement
c. Setpoint
d. Integral circuit
Answer: b
4. The function of the integral (reset) mode is to:
a. Oppose change in measurement
b. Automatically adjust the controller’s gain
c. Eliminate offset
d. Stabilize the controlloop
Answer: c
5. Automatic controllers operate on the difference between set point and measurement, which is called:
a. Offset
b. Bias
c. Error
d. Feedback
Answer: c
6. A two-position controller (on/off) always:
a. Controls with a fixed offset
b. Controls around a point
c. Automatically adjusts its integral time
d. Requires precise tuning
Answer: b
7. Gain and proportional bands are:
a. Reciprocally related
b. Two different control modes
c. Adjusted independently 0f one another
d. Controller functions calibrated in time units
Answer: a
8. When we adjust integral time in a controller:
a. We determine an RC time constant in the controller’s internal feedback path
b. We adjust the time it will take for integral to equal derivative
c. We set the process time constant so that it will always equal 1
d. What happens specifically depends on the type of controller, pneumatic
Answer: a
9. A proportional controller will have an offset difference between set point and control point:
a. At all times
b. Equal to the proportional band setting
c. That depends on process load
d. That will eventually vanish
Answer: c
10. If it were possible for a proportional controller to have a true 0 percent proportional band, the controller gain would have to be:
a. Unity
b. 0
c. 100
d. Infinite
Answer: d
11. If the proportional band of the controller is adjusted to the minimum possible value, the control action is likely to be:
a. On/off
b. With maximum otIset
c. Excellent
d. Inoperative
Answer: a
12. The following symbol appears in an instrument diagram. It represents :
a. Flow rate controller
b. Fixed control point
c. Frequency converter
d. Final control element
Answer: a
13. All control systems that fit into the usual pattern are:
a. Open-Loop
b. Nonself-regulating
c. Closed-loop
d. On/off
Answer: c
14. If operating properly, automatic control will always:
a. Reduce manpower
b. Reduce costs
c. Make the process operate more uniformly
d. Decrease maintenance
Answer: c
