QUESTION & ANSWERS FOR CONTROL SYSTEM_DCS_P&ID

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QUESTION & ANSWERS FOR CONTROL SYSTEM_DCS_P&ID

1.        Which component determines that the temperature is below the set point?
 Sensor
 Transmitter
 Controller
 Final
control element
2.        What are the components of a typical industrial two-position control feedback loop?
Two-position controller, sensor, transmitter, and final control element
 Two-position controller, sensor, receiver, and first stage element
 Control valve, transmitter, and receiver
 Two-position controller, sensor, transmitter, and set-point reference
3.        A heating system using a two-position control turns on when:
 The room temperature remains constant for 24 hours
 The room temperature falls below a set point
 The feedback loop fails to send the signal
 The feedback loop fails to open the valve
4.        One characteristic of the two-position control is
It is a simple system with continuously modulating valve signal
It is a system that eliminates oscillations
It is a simple system with an on and off position
It is a simple system that yields a constant controlled variable
5.        In a two-position control, which component detects changes in the controlled variable?
 Solenoid valve
 Final control element
 Pressure switch
 Sensor
6.        In a two-position control what causes oscillations in the controlled variable?
The system cannot Select the reason why a two- position control causes oscillations in the respond
immediately to changes in the controlled variable response time of the sensor is too fast to control oscillations.
 The valve reacts too slowly to changes in the controlled variable.
7.        The system does not respond to changes in the controlled variable?
The system does not respond to changes in the controlled variable.
 The system cannot respond immediately to changes in the controlled variable.
 The response time of the sensor is too fast to control oscillations.
 The valve reacts too slowly to changes in the controlled variable.
8.        Which of the following statements about a two-position control is correct?
The valve reacts tooslowly to changes in the controlled variable
 The response time of the sensor is too fast to control oscillations
 The system cannot respond immediately to changes in the controlled variable
 The system does not respond to changes in the controlled variable
9.        Identify the correct reason that the
two-position control causes oscillations in the controlled variable.
 The response time of the sensor is too fast to control oscillations
 The valve reacts too slowly to changes in the controlled variable
 The system does not respond to changes in the controlled variable
 The system cannot respond immediately to changes in the controlled variable
10.     In order to keep boiler pressure within tolerable limits it is best to use :
Two-position control
 Proportional control
 Fuel flow control
 Derivative control
11.      Changes in proportional control action are expressed as 
An input ratio
  An output range
  A gain factor
  A sensitivity response
12.   In the proportional control mode, the final element:
 Can be  positioned at any point within the throttling range
 Can be positioned at three discreet points
 Cannot be changed
 Can only be positioned on or off
13.     The final control element in the proportional control mode:
 Can be positioned at three discreet points
 Can be positioned at any point within the throttling range
 Cannot be changed
 Can only be positioned on or off
14.    In the proportional control mode, oscillations are minimized because:
 Integral control is used
 There are multiple offsets programmed
 A finer degree of control is possible than the on-off mode
 Thesensor is more accurate than in the two-position position
15.     Proportional control action provides:
 Immediate control
 On-off control
 Intermittent control
 Continuous control
16.     What is one relationship between a change in the controlled variable and a proportionally controlled valve?
An increase in the controlled variable causes the valve to contract towards the closed position
An increase in the controlled variable causes the valve to expand towards the fully opened position
A decrease in the controlled variable causes the valve to contract towards the closed position
A decrease in the controlled variable creates no change in the valve
17.     One of the relationships between a change in the controlled variable and a proportionally controlled valve is:
An increase in the controlled variable causes the valve to expand towards the fully opened position
An increase in the controlled variable causes the valve to contract towards the closed position
A decrease in the controlled variable causes the valve to contract towards the closed position
A decrease in the controlled variable creates no change in the valve
18.     In a proportionally controlled system, when the valve contracts towards the closed position the controlled variable must have:
 Reached the offset
 Decreased
 Increased
 Oscillated
19.     In a proportionally controlled system, when the valve expands towards the fully opened position the controlled variable must have:
 Reached the offset
 Increased
 Oscillated
 Decreased
20.     Which of the following statements is correct concerning proportional band and gain?
 A wide proportional band produces a less sensitive response
 A narrow proportional band produces a less sensitive response
 A low gain corresponds to a more sensitive response
 A high gain corresponds to a less sensitive response
21.     The relationship between proportional band and gain is:
 Directly proportional
 Inversely proportional
 An integral relationship
 A derivative relationship
22.     What is the relationship between proportional band and gain?
 A narrow proportional band has a low gain and a wide band has a high gain
 The amount of band width and the amount of gain are the same
A wide proportional band has a low gain and a narrow band has a high gain
 The amount of band width and the amount of gain are unrelated
23.   Which of the following statements best describes the relationship between proportional band and gain?
 A narrow proportional band has a low gain and a wide band has a high gain amount of band width and the amount of gain are the same
 The amount of band width and amount of gain are unrelated
 A wide proportional band has a low gain and a narrow band has a high gain
24.     Excessive proportional action results in:
 Offset
 Gain
 Banding
 Oscillation
25.     An advantage of a PID controller is:
 It responds rapidly to upsets
 It canbe used with flow control processes
 It controls for offset
 It prevents oscillation
26.     Offset is best defined as:
 The difference between the set point and the controlled variable
 The width of the proportional band
 The setamount of oscillations in a given time frame
 The derivative of the set point value and the controlled variable
27.     The best definition for the term offset is:
 The width of the proportional band
 The difference between the set point and the controlled variable
 The setamount of oscillations in a given time frame
 The derivative of the set point value and the controlled variable
28.     Choose the best description of offset.
 Thevalue of the set point with inherent fluctuations
  The unnecessary deviation from the set point over time
 The difference between the set point and the controlled variable
 The derivative of the set point value and the controlled variable
29.     The term offset as it applies to proportional control systems is:
 The value of the set point with inherent fluctuations
 The unnecessary deviation from the set point over time
 The derivative of the set point value and the controlled variable
 The difference between the set point and the controlled variable
30.     Integral action continues to provide additional control:
 As long as the offset is present
Until the offset is present
 After the control elements are corrected
 As long as the proportional band is 50% or less
31.    Integral action performs checking, adjusting, and rechecking:
 Until deviations shut down the system
 Until the process returns to the set point
 After  the controlled variable returns to the set point
 Until proportional control takes over
32.     Repeated control action is a characteristic of:
 Gain
 Derivative
 Integral action
 Proportional band
33.     The main purpose of integral action is to:
 Monitor the set point
 Provide intermittent control in the throttling range
 Maintain proportional band/gain ratios
 Provide continuous control until the variable is back at the set point
34.     PID control is useful in processes that:
 Are slow to respond and need more control
 Are fast responding and need little control
 Need constant stabilizing
 Need no control
35.     The function of PID control is to :
 Overcome flow control deviations
 Provide efficient and accurate means of automatic control
 Reposition the final control element when signal is interrupted
 Provide the best means of manual control
36.     The most complex process control mode is the:
 Derivative
 Integral
 PID
 Proportional
37.     Which control mode prevents overshoot andreduces oscillations?
 Two-position
 Integral
 Derivative
 PID

 

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