Power Engineering 4A – Unit 9: Plant Instrumentation Exam – Most Recent Study Guide & Practice Questions

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Power Engineering 4A - Unit 9 - Plant Instrumentation Most Recent exam
COMPLETE (2026) EXAM Questions and Answers (Verified Answers) (Latest
Update 2026) Graded A+

Automatic systems which can make decisions are termed
A) annunciation systems.
B) logic systems.
C) indicating systems.
D) open loop systems.
E) cascading systems. - CORRECT ANSWER ✔✔✔✔✔ B

In an automatic control system, the controller output signal manipulates the
A) transmitter.
B) sensing element.
C) recorder.
D) control valve.
E) primary element. - CORRECT ANSWER ✔✔✔✔✔ D

The second from last step in an automatic boiler programmed shutdown sequence is
A) timer motor stops.
B) flame failure relay opens.
C) post purge completes.
D) operating control switch contacts close.
E) flame failure switch contacts open. - CORRECT ANSWER ✔✔✔✔✔ C

Analog inputs provided to PLC are typically variable _________ or variable voltage
signals from pressure, level, temperature, flow or other transmitters.
A) current
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, B) inductance
C) resistance
D) capacitance
E) frequency - CORRECT ANSWER ✔✔✔✔✔ A
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During the housekeeping scan, the PLC
A) energizes or de-energizes output devices
B) communicates with other network devices and programming devices
C) executes its programmed logic
D) checks the state of all the input devices
E) checks the state of all the output devices - CORRECT ANSWER ✔✔✔✔✔ B

______________ are designed for technical applications.
A) Workstations
B) Personal computers
C) Controllers
D) Servers
E) Technical laptops - CORRECT ANSWER ✔✔✔✔✔ A

The type of air damper to provide with a much more precise air flow control,
especially at small openings, is
A) parallel blade damper
B) opposed blade damper
C) variable outlet vane damper
D) variable inlet vane damper - CORRECT ANSWER ✔✔✔✔✔ B

The Chromel-Alumel (Type K) thermocouple can be used in the temperature range of
A) -184 oC to 371oC
B) -18oC to 760oC
C) -185oC to 1260oC
D) 538oC to 1482oC
E) 200oC to 3000oC - CORRECT ANSWER ✔✔✔✔✔ C

One common mass flow meter is called
A) Weir meter
B) Coriolis meter
C) Variable area meter
D) Doppler meter - CORRECT ANSWER ✔✔✔✔✔ B

With reference to the controller design, CPU stands for
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, A) central processing unit
B) controlled programmable utility
C) combined power utility
D) controlled personal unit - CORRECT ANSWER ✔✔✔✔✔ A
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A Bourdon tube is often in the shape of a spiral so that
A) its final output has less travel.
B) gears can be used for final output.
C) higher pressures can be sensed.
D) more power and travel of the free end occurs.
E) its sensitivity will be decreased. - CORRECT ANSWER ✔✔✔✔✔ D

Smart transmitters cannot:
A) Receive multiple inputs and outputs
B) Communicate and change configuration details
C) Change the power source(s)
D) Signal alarms and error conditions - CORRECT ANSWER ✔✔✔✔✔ C

In a power plant, networking of computers is advantageous because
A) operators can use any computer to regulate the process.
B) shift operators can communicate with each other by e-mail.
C) computing power is distributed and the loss of one computer is less serious.
D) complete control will be maintained during a power failure.
E) viruses may be easily eradicated throughout the system. - CORRECT ANSWER
✔✔✔✔✔ C

Electronic control systems do NOT use
A) Sensors and transmitters
B) Controllers
C) Actuators, relays, control valves, and dampers
D) Indicating and interfacing devices
E) 4 to 20 mV recording sensors - CORRECT ANSWER ✔✔✔✔✔ E

Differential and incremental backups take less time and storage space than full
backups.
A) True
B) False - CORRECT ANSWER ✔✔✔✔✔ A

A strain gauge is commonly used to measure
A) corrosion of pipe walls.
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, B) pressures or forces on column.
C) levels in oil tanks.
D) the densities of materials.
E) the tension given by a compressive load. - CORRECT ANSWER ✔✔✔✔✔ B
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Analog signals vary over a range of values. Analog input signals must be _________
to digital format before they can be processed by computers. When final control
elements are analog, the digital control output signals from process computers must be
converted to _________ signals.
A) analog - positive
B) analog - negative
C) converted - analog
D) digital - positive
E) digital - negative - CORRECT ANSWER ✔✔✔✔✔ C

Immersion thermostat (Aquastat) is used to sense and control the temperature of
A) solids
B) non-homogeneous substances
C) vapors
D) gases
E) liquids - CORRECT ANSWER ✔✔✔✔✔ E

In computer terminology, HDD means
A) hard documented drive
B) home directed device
C) home disk drive
D) hard disk drive
E) homogeneous digital drive - CORRECT ANSWER ✔✔✔✔✔ D

The DCS controller receives information from input modules and sends information to
A) field transmitters
B) transducers
C) output modules
D) workstations
E) HMIs - CORRECT ANSWER ✔✔✔✔✔ C

A multiplexer is used to regulate tasks in sequence as often as
A) once per hour.
B) twice per minute.
C) four times per minute.
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