AZ L-60 Controls & Automation Contractor
Exam Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
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1. What is the primary function of a programmable logic controller
(PLC) in an automated control system?
a. To provide mechanical power to equipment
b. To store electrical energy for backup
c. To monitor inputs, execute programmed logic, and control outputs
d. To replace all electrical protection devices
Rationale: A PLC receives signals from field inputs such as switches
and sensors, processes those signals according to its program, and
controls outputs such as motors, valves, relays, and actuators. It is the
central decision-making device in many industrial automation
systems.
, 2. Which device is commonly used to detect whether an object is
present without physical contact?
a. Float switch
b. Limit switch
c. Proximity sensor
d. Pushbutton
Rationale: Proximity sensors detect objects without requiring physical
contact. Depending on the sensor type, they may use inductive,
capacitive, ultrasonic, or other detection principles.
3. An inductive proximity sensor is primarily designed to detect:
a. Glass objects only
b. Liquid levels only
c. Metallic objects
d. Air pressure
Rationale: Inductive proximity sensors generate an electromagnetic
field and detect changes caused by nearby conductive metal objects.
They are widely used for machine-position and part-detection
applications.
4. What is the purpose of a normally closed (NC) control contact?
,a. It remains open until energized
b. It is closed in its normal, de-energized state
c. It always carries motor current
d. It prevents all overload conditions
Rationale: A normally closed contact is closed when the controlling
device is in its normal state. When the device operates, the contact
opens. NC contacts are commonly used in stop circuits and safety-
related control logic.
5. Which component converts an electrical control signal into
mechanical movement?
a. Transformer
b. Fuse
c. Terminal block
d. Actuator
Rationale: An actuator receives an electrical, pneumatic, hydraulic, or
electronic command and produces physical movement. Examples
include motorized valves, solenoids, and electric linear actuators.
6. What is the principal purpose of a control transformer?
a. Increase motor horsepower
b. Provide a suitable voltage for control circuits
, c. Protect conductors from mechanical damage
d. Convert AC power into compressed air
Rationale: Control transformers provide a separate, appropriately
rated voltage for control components. For example, a system supplied
at a higher line voltage may use a lower control voltage for relays,
contactors, and PLC inputs.
7. A thermocouple is primarily used to measure:
a. Pressure
b. Flow
c. Temperature
d. Electrical resistance
Rationale: A thermocouple produces a small voltage related to the
temperature difference between its measuring junction and reference
junction. It is widely used for industrial temperature measurement.
8. What does an analog input module typically allow a PLC to
receive?
a. Only two-state signals
b. Mechanical torque
c. Continuously varying signals such as 0–10 V or 4–20 mA
d. Three-phase motor power
Exam Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary function of a programmable logic controller
(PLC) in an automated control system?
a. To provide mechanical power to equipment
b. To store electrical energy for backup
c. To monitor inputs, execute programmed logic, and control outputs
d. To replace all electrical protection devices
Rationale: A PLC receives signals from field inputs such as switches
and sensors, processes those signals according to its program, and
controls outputs such as motors, valves, relays, and actuators. It is the
central decision-making device in many industrial automation
systems.
, 2. Which device is commonly used to detect whether an object is
present without physical contact?
a. Float switch
b. Limit switch
c. Proximity sensor
d. Pushbutton
Rationale: Proximity sensors detect objects without requiring physical
contact. Depending on the sensor type, they may use inductive,
capacitive, ultrasonic, or other detection principles.
3. An inductive proximity sensor is primarily designed to detect:
a. Glass objects only
b. Liquid levels only
c. Metallic objects
d. Air pressure
Rationale: Inductive proximity sensors generate an electromagnetic
field and detect changes caused by nearby conductive metal objects.
They are widely used for machine-position and part-detection
applications.
4. What is the purpose of a normally closed (NC) control contact?
,a. It remains open until energized
b. It is closed in its normal, de-energized state
c. It always carries motor current
d. It prevents all overload conditions
Rationale: A normally closed contact is closed when the controlling
device is in its normal state. When the device operates, the contact
opens. NC contacts are commonly used in stop circuits and safety-
related control logic.
5. Which component converts an electrical control signal into
mechanical movement?
a. Transformer
b. Fuse
c. Terminal block
d. Actuator
Rationale: An actuator receives an electrical, pneumatic, hydraulic, or
electronic command and produces physical movement. Examples
include motorized valves, solenoids, and electric linear actuators.
6. What is the principal purpose of a control transformer?
a. Increase motor horsepower
b. Provide a suitable voltage for control circuits
, c. Protect conductors from mechanical damage
d. Convert AC power into compressed air
Rationale: Control transformers provide a separate, appropriately
rated voltage for control components. For example, a system supplied
at a higher line voltage may use a lower control voltage for relays,
contactors, and PLC inputs.
7. A thermocouple is primarily used to measure:
a. Pressure
b. Flow
c. Temperature
d. Electrical resistance
Rationale: A thermocouple produces a small voltage related to the
temperature difference between its measuring junction and reference
junction. It is widely used for industrial temperature measurement.
8. What does an analog input module typically allow a PLC to
receive?
a. Only two-state signals
b. Mechanical torque
c. Continuously varying signals such as 0–10 V or 4–20 mA
d. Three-phase motor power
