Review Questions on Fundamentals of Process Control**

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Those who find it useful can take a look at the basic questions on process control. I. Multiple-choice questions 1. In a simple control system, the element that receives the error signal is (B). A. Transmitter B. Controller C. Control valve D. Controlled object 2. In a simple control system, disturbances mainly affect the (D) component. A. Measurement transmitter B. Controller C. Control valve D. Controlled object. 3. The measured value of the controlled variable is the signal output by the (D) unit. A. Control valve B. Controller C. Controlled object D. Transmitter 4. The controller element must have (A) characteristic when selecting PID properties. A . P B . I C . D D . P and I5. For a system whose controlled variable is temperature, the controller generally adopts (D) characteristics. A. P B. PI C. PD D. PID 6. Proportional action is based on the action of (A). A. The magnitude of the deviation B. Whether a deviation exists C. The rate of change of the deviation D. All of the above. 7. The integral function operates based on the action of (C). A. The rate of change of deviation B. The magnitude of deviation C. Whether deviation exists D. None of the above. 8. Differential action is based on the operation of (C). A. The magnitude of the deviation B. Whether a deviation exists C. The rate of change of the deviation D. All of the above. 9. Differential action is incorporated into controllers in order to overcome (A) of the controlled system. A. Inertia lag, capacity lag B. Pure lag C. Inertia lag, pure lag D. Capacity lag, pure lag 10. The signal range that a pneumatic diaphragm control valve can receive is (A) MPa: A. 0.02~0.1 B. 0.02~0.06 C. 0.09~0.12 D. 0.1~0.15 11. The ratio of the maximum flow rate to the minimum flow rate that a control valve can regulate is referred to as the (C) of the control valve. A. Flow characteristics B. Ideal range C. Adjustable ratio D. Actual characteristics 12. The ideal flow characteristic of a control valve depends on (D). A. Piping conditions B. Valve seat shape C. Value of C D. Valve stem shape 13. Opening the bypass valve connected in parallel with the control valve will increase the adjustable ratio (A). A. Become smaller B. Become larger C. Remain unchanged D. Become zero. 14. When a control valve is of the air-operated shut type, it means (B). A. No signal, valve closed; B. No signal, valve open; C. As the signal increases, the push rod moves downward; D. As the signal increases, the push rod moves upward. 15. The reason why silicone oil is generally used as the filling fluid in flanged level gauges is (D). A. Silicone oil is inexpensive. B. Silicone oil is heavy. C. Silicone oil vaporizes easily. D. Silicone oil has a high boiling point, a low expansion coefficient, and a low freezing point. 16. The DDZ—Ⅱ type transmitter (C) A. Uses a two-wire system at the field level. B. Each unit is powered by 24V. C. Uses a four-wire system at the field level. D. Is a safety-proof instrument. 17. Regarding the DDZ—Ⅲ type transmitter, the correct statement is (D). A. The signal transmitted on-site is 0~~10mA. B. Current is used for transmitting and receiving signals. C. Each unit is powered separately by 220V. D. The signal transmitted on-site is 4~~20mA. 18. Spring tube pressure gauges generally have the best accuracy at their (C) scale position. A.1/3 B.1/2 C.2/3 D.3/4 19. When the temperature at the cold end remains constant, the direction and magnitude of the thermoelectromotive force depend on the (D) of the thermoelectric electrode and the temperature at the hot end. A. Thickness B. Length C. Temperature D. Material 20. The greater the proportionality of the controller, then (D). A. The greater the magnification, B. The stronger the proportional effect, C. Unstable conditions, D. A stable curve. 21. The signal transmitted in the control room of electric type III instruments is (D). A. 220V B. 4~2mA C. 0~10mA D. 1~5V 22. The power supply used for Type III electrical meters is (C) volts. A. 220V B. 36V C. 24V D. 110V 23. DDZ—III type transmitter (A). A. The two-wire system is used on-site. B. It is powered by 24V. C. The four-wire system is used on-site. D. It is a safety and explosion-proof instrument. 24. The instrument tag number consists of (C). A. Functional symbols and numerical codes B. Letter codes and section numbers C. Letter codes and numerical codes D. Parameter symbols and sequence numbers 25. For a distillation process, in order to control the quality of the product at the top of the tower, under constant pressure conditions, the controlled variable that is generally chosen is (A). A. Top temperature of the tower B. Pressure at the top of the tower C. Flow rate into the tower D. Output volume from the top of the tower. 26. When controlling the top temperature of the tower, (B) is generally used as the control variable. A. Flow rate of the heating medium at the bottom of the tower B. Return flow rate at the top of the tower C. Feed rate D. Extraction rate from the top of the tower 27. Among the methods for taking pressure readings using orifice plates, the most widely used one is (B). A. Angle connection pressure tapping and radius distance pressure tapping B. Angle connection pressure tapping and flange pressure tapping C. Flange pressure tapping and radius distance pressure tapping D. Pipe connection pressure tapping and theoretical pressure tapping 28. The most important controlled variable in a chemical reactor is (B). A. Reaction pressure B. Reaction temperature C. Feed flow rate D. Outlet flow rate 29. Overall, a cascade control system is still a (A) control system. A. Fixed value B. Ratio C. Feedforward D. Lag 30. The pressure indicated by the pressure gauges used in industry is (B). A. Atmospheric pressure B. Gauge pressure C. Negative pressure D. Absolute pressure 31. To repair a functioning control valve, the instrument technician should first do (D). A. Remove the control element B. Lower temperature and pressure C. Go to the site to resolve the fault D. Inform the process engineers to switch from automatic to manual control and use a bypass line for control. 32. A simple feedforward system is a control system that can compensate for (C). A. The difference between X and Z B. The change in the controlled variable C. The change in the disturbance D. The change in the control variable. 33. For a system whose controlled variable is pressure, the control law used by the controller is generally one with (D) characteristics. A.P B.PD C.PID D.PI34. The load resistance of the smart meter is (B) Ω. A.100 B.250 C.300 D.1000 35. For measuring the liquid level of most process vessels, a (D) type level gauge can be used. A. Anti-rotation B. Pressure C. Weight D. Differential pressure 36. To calibrate industrial pressure gauges with a range of 0~1.6 MPa and grade 1.5, a standard pressure gauge (A) should be used. A. 0~1.6MPa, Class 0.5 B. 0~2.5MPa, Class 0.35 C. 0~0.25MPa, Class 1.0 D. 0~4.0MPa, Class 0.25 37. The resistance value of the Cu50 thermistor at 0°C is (B) Ω. A.0 B.50 C.100 D.15038. The accuracy indicator of a control system is (D). A. Attenuation ratio B. Overshoot time C. Maximum deviation D. Residual error. 39. When the pressure difference before and after the control valve is small and a low leakage rate is required, generally (　B　) valves can be used. A. Sleeve valve B. Single-seat valve C. Diaphragm valve D. Butterfly valve 40. For a 1151 transmitter with an accuracy class of 0.5, the maximum absolute error does not exceed (B) mA. A.0.1 B.0.08 C.0.05 D.0.0141. The valve positioner can change the (B) of the control valve. A. Adjustable ratio B. Flow characteristic C. Maximum flow rate D. Switch type 42. In the composition of an instrument tag, the first letter represents (D). A. Functional letter code B. Work order number C. Sequence D. Letter code of the variable to be measured 43. When calibrating instruments, it is generally necessary to adjust (C). A. 2 points B. 3 points C. 5 points D. 6 points 44. The structure of a measuring instrument does not include (D). A. Detection and sensing section B. Conversion and transmission section C. Display section D. Adjustment section 45. Depending on the physical quantity being measured, measuring instruments can be classified into (A). A. Pressure measuring instruments, level measuring instruments, flow measuring instruments, temperature measuring instruments, analytical instruments, etc. B. Indicating type, recording type, signal type, remote indicating type, cumulative type, etc. C. Industrial instruments and standard instruments D. None of the above. 46. The range of an instrument with a temperature measurement range of -50 ~ +1370°C is (B). A. 1370℃ B. 1420℃ C. 1320℃ D. -50 ~ 1370℃47. An open water tank is 10m high; when it is filled with water, the pressure at the bottom of the tank is (B). A. 0.98MPa B. 0.098MPa C. 1MPa D. 0.1MPa48. The control valve receives the control signal sent by the regulator, and regulates (B) to keep it within the desired range, thereby achieving automatic control of the production process. A. Manipulating variable B. Controlled variable C. Disturbance D. Error 49. The general steps for putting a well-designed control system into operation are (A). A. Manual operation, remote control, automatic control B. Remote control, automatic control C. Automatic control D. No fixed requirement 50. The calibration grade of nickel-chromium/nickel-silicon thermocouples is (B). A. E B. K C. S D. T51. Throttle orifice plates generally have certain requirements regarding the straight pipe sections before and after them; the correct answer is (A). A. 10D before and 5D after B. 10D before and 3D after C. 5D before and 3D after D. 8D before and 5D after 52. Level refers to ( D ). A. Liquid level B. Material level C. Interface level D. All of the above