QUESTIONS & ANSWERS INSTRUMENTATION_ENGINEERING
Which of the following is one of the three steps that occur in the control of industrial processes?
- Make a decision
- Identify process variable
- Minimize risks
- Ensure quality
A key component in most feedback control loops is a:
- Thermostat
- Transmitter
- Pressure gage
- Fuel valve
Which of the following are the four most common process variables?
- Temperature, pressure, level, and flow
- Temperature, density, flow, and precision
- Level, precision, pressure, and flow
- Density, pressure, level, and flow
What is the correct order of steps that occur in any controlled process?
- Measure variables, make a decision, and take action
- Collect data, measure variables, and take action
- Measure variables, take action, and provide feedback
- Collect data, make a decision, and provide feedback
What type of variable is measured and compared to the desired value?
- Controlled
- Set
- Manipulated
- Adjusted
What type of variable is measured and compared to the desired value?
- Adjusted
- Controlled
- Set
- Manipulated
In process control, the action taken to eliminate any deviation is the adjustment of the:
- Controlled variable
- Set variable
- Manipulated variable
- Adjusted variable
To eliminate deviation in process control you can alter the:
- Controlled variable
- Set variable
- Adjusted variable
- Manipulated variable
A change in the demand on a system is referred to as:
- Upset
- Adjustment
- Manipulation
- Deviation
The constant measurement and response to information is called:
- Disturbance monitoring
- Feedback
- Feedback control loop
- Upset
The instruments that gather information, make decisions, and take action are each part of the:
- Feedback group
- Set point
- Feedback control loop
- Process group
A factor outside the loop that affects the controlled variable is referred to as: >
- Shift
- Adjustment
- Gage
- Upset
What are the four key components used in most feedback control loops?
- Sensor, transmitter, controller, and final control element
- Sensor, processor, transducer, and controller
- Processor, transmitter, receiver, and final control element
- Signal, transducer, controller, and processor
Which of the following is the first event in a typical feedback control loop sequence?
- The sensor, or transmitter, signals a controller of a change in a measured variable
- The controller sends a signal to the final control element
- A transmitter sends a signal to a control valve
- The final control element adjusts the system
What is the final event in a typical feedback control loop sequence?
- A transmitter sends a signal to a control valve
- The final control element adjusts the system
- The controller sends a signal to the final control element
- The final control element receives a signal from the controller
In a typical feedback control loop sequence, the field transmitter sends a signal to the:
- Final control element
- Sensor
- Controller
- Pressure gage
In a typical feedback control loop sequence, the controller sends a signal to the:
- Pressure gage
- Sensor
- Transmitter
- Final control element
The term that describes how consistently a sensor indicates the same input value at different times is:
- Validity
- Accuracy
- Precision
- Reliability
A common method of transmitting standard instrument signals is:
- Electrically
- Optically
- Mechanically
- Electronically
The time it takes to respond to a change in a controlled variable is called:
- Response time
- Controller delay
- Action sequence
- Reaction time
The time it takes for the indicated temperature to respond and accurately reflect the actual temperature is called:
- Sensor response time
- System response time
- Reaction time
- Controller delay
The change cycle is initiated by:
- System response
- Controller response
- Sensor response
- Transmitter response
Controller response affects:
- Transmitter response
- Sensor response
- Reaction time
- System response
What type of measurement closely indicates the actual value of the controlled variable?
- Accurate
- Valid
- Precise
- Reliable
What type of measurement consistently indicates the same input value at different times?
- Valid
- Precise
- Accurate
- Reliable
The term that describes how closely a sensor reflects a controlled variable is:
- Precision
- Validity
- Accuracy
- Reliability
The term that describes how consistently a sensor indicates the same input value at different times is:
- Validity
- Reliability
- Accuracy
- Precision
Which of the following are the most common ways of transmitting instrument signals?
- Digitally, pneumatically, and electronically
- Magnetically and hydraulically
- Hydraulically and mechanically
- Through mechanical movement or varying resistance
Two common types of final control elements used in process industries are:
- Electrical and pneumatic
- Optical and electrical
- Optical and mechanical
- Pneumatic and mechanical
Most final valve control elements are operated by:
- Optic or magnetic actuators
- Pneumatic or electrical actuators
- Magnetic control valves
- Motor driven gears
What are the two most common methods of final control in process industries?
- Optical and electrical
- Optical and magnetic
- Electrical and pneumatic
- Magnetic and mechanical
Two common types of final control elements used in process industries are:
- Electrical and magnetic
- Pneumatic and optical
- Optical and magnetic
- Electrical and pneumatic
The advanced control process that monitors a second variable in addition to the primary controlled variable is known as:
- Cascade control
- Ratio control
- Feedback loop control
- Feed forward control
Which type of control monitors a second variable at a different point in the process to help the system react to upsets more quickly?
- Cascade
- Ratio
- Feed forward
- Single-loop
What type of control measures a variable before it affects a set point?
- Ratio
- Feed forward
- Feedback
- Cascade
Which type of control monitors two different types of materials being combined and ensures that the right proportions are maintained?
- Feed forward
- Single-loop
- Ratio
- Cascade
What type of control is often used in combination with feedback control to reduce variations from set point?
- Single-loop
- Ratio
- Cascade
- Feed forward
Under what condition is a Wheatstone Bridge balanced?
- When resistors indicate pressure changes
- When there is process pressure
- When all legs are in parallel
- When current flow through each leg is equal
A linear variable capacitor indicates change in process pressure by:
- Altering resistance in resistors
- Changing the voltage to the transformer
- Moving the slide on the potentiometer
- Changing the distance between the plates
Which of the following best describes the use of electrical circuits in electrical pressure transducers?
- To convert mechanical motion into electrical values
- To modify electrical values into a measure of mechanical motion
- To determine applied pressure values
- To measure current output against a measured electrical value
On an electrical pressure transducer, what is measured to determine pressure?
- Voltage
- Changes in current flow
- Input pressure
- Output pressure
What is indicated by measured changes in current flow?
- Mechanical value
- Voltage
- Pressure
- Electrical motion
Moving the slide on a potentiometer will result in which of the following?
- Decrease in pressure
- Static voltage
- Increase in value
- Change in resistance
For accurate measurements, which type of circuit is most often used?
- Wheatstone bridge
- Potentiometric transducer
- Resistance indicator unit
- Series circuit
Which term describes a bridge where the resistance of all four resistors is equal?
- Equal resistance
- Balanced bridge
- Quad equilibrium
- Parallel equation
A typical bridge circuit has how many parallel legs?
- Four
- None
- Two
- Six
An absence of process pressure will result in which of the following?
- Parallel equation
- Equal resistance
- Process abstinence
- Balanced bridge
What causes the slide on a potentiometer to move?
- Change in pressure
- Gravitational pull
- Increase in voltage
- Equal resistance
Which of the following will cause an increase in current flow through a circuit?
- Balanced resistance
- Lower resistance
- Equal resistance
- Greater resistance
Which of the following is NOT a type of electrical pressure element?
- Linear Variable Differential Transformer
- Potentiometer
- Nanometer
- Linear Variable Capacitor
A decrease in a potentiometer’s resistance will result in which of the following?
- Decrease in current flow
- No change in current flow
- Reverse-direction of current flow
- Increase in current flow
What separates the two metal plates in a capacitor?
- Dielectric
- Spacer
- Circuit
- Wire
Which of the following is NOT a factor in determining a capacitors amount of opposition to current flow?
- Distance between plates
- Use of circuit
- Type of dielectric
- Size of metal plates
In addition to storing an electrical charge, which of the following opposes or offers resistance to changes in current flow?
- Transducer
- Potentiometer
- Capacitor
- Transformer
The dielectric is composed of which of the following types of material?
- Resistive
- Corrosive
- Conducting
- Insulating
Which device detects pressure by means of a wire that tensions or relaxes?
- Potentiometer
- LVDT
- Bonded Strain Gage
- Unbonded Strain Gage
Which type of pressure-sensing device is well suited for miniaturized electronic circuits?
- Linear variable capacitor
- Potentiometer
- Bonded strain gage
- Wheatstone bridge
What happens when the armature on an unbonded strain gage moves?
- The tensioned, resistance increases; when relaxed, resistance decreases
- The level of current remains constant when the armature moves
- When the armature moves, tension reduces resistance
- The level of pressure is reduced when the wire is tensioned
In a bonded strain gage, what is mounted to that part of the pressure element that does not move?
- The transducer
- The slip
- The tensioner
- The pinion
What is the basic operating principle of a strain gage?
- Resistance will decrease under tension and increase when relaxed
- Resistance will decrease and increase when tensioned
- Resistance will increase under tension and decrease when relaxed
- Resistance will stay the same until the armature no longer moves
An increase or decrease of tension in a strain gage is caused by which of the following?
- Movement of the slip
- Zero pressure
- Increase in current
- Movement of the armature
Which of the following is NOT a commonly used crystal in pressure measuring devices?
- Bromide quartzite
- Rochelle salt
- Barium titanate
- Quartz
What action causes a crystal to produce a measurable voltage?
- An increase in applied current
- Being subject to strain
- Exposure to kinetic energy
- A decrease of pressure
Which factor determines the amount of voltage a crystal will produce?
- The volume of available kinetic energy
- The size and color of the crystal
- The amount of pressure applied
- The ambient temperature of the crystal
Which of the following is a characteristic of crystals that produce a voltage when subjected to pressure?
- They can produce a variety of voltages from a specific pressure
- They never produce the same voltage twice when subjected to a specific pressure
- They can usually produce the same voltage when subjected to a specific pressure
- They always produce a specific voltage when subjected to a specific pressure
What type of device is used to protect process-measuring instruments from vapor condensate?
- Seal Pot
- Snubber
- Pigtail
- Vacuum tube
INSTRUMENTATION AND CONTROL ENGINEERS QUESTIONS AND ANSWERS