AK Electrical Administrator – Controls Exam
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Answers) Plus Rationale 2027 Q&A| Instant
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1. What is the primary purpose of an electrical control circuit?
a. To increase the available utility voltage
b. To provide mechanical support for conductors
c. To control the operation of electrical equipment
d. To eliminate the need for overcurrent protection
Rationale: A control circuit provides the signals necessary to start,
stop, sequence, regulate, or otherwise control electrical equipment. It
normally operates control devices such as relays, contactors, timers,
and sensors rather than supplying the full load power.
2. Which device is commonly used to open and close a motor power
circuit using a low-power control signal?
,a. Fuse
b. Transformer
c. Contactor
d. Receptacle
Rationale: A contactor is an electrically operated switching device
designed to control power circuits, particularly motor loads. A
relatively small control current energizes its coil, causing the main
contacts to open or close.
3. What is the purpose of a normally open pushbutton?
a. To continuously energize a circuit
b. To close the circuit only while the button is actuated
c. To protect a motor from overload
d. To reduce line voltage
Rationale: A normally open pushbutton has contacts that remain open
when the button is at rest. Pressing the button closes the contacts and
allows current to flow through the control circuit.
4. A normally closed stop pushbutton is generally used to:
a. Increase motor speed
b. Energize a heater
,c. Interrupt the control circuit when pressed
d. Measure current
Rationale: Stop pushbuttons are commonly normally closed so that
the control circuit remains complete during normal operation.
Pressing the button opens the circuit and de-energizes the controlled
equipment.
5. What is the function of a motor starter?
a. Only to measure motor voltage
b. Only to provide grounding
c. To control motor operation and provide motor overload protection
d. To convert AC to DC
Rationale: A typical motor starter combines a contactor or similar
switching device with overload protection. This arrangement permits
the motor to be started and stopped while protecting it from
sustained overload conditions.
6. What does an auxiliary contact on a contactor commonly provide?
a. Short-circuit protection for the utility service
b. A control signal or holding circuit
c. Mechanical lubrication
d. Transformer cooling
, Rationale: Auxiliary contacts are separate from the main power
contacts and are frequently used in control circuits. They can provide
electrical interlocking, status indication, or a seal-in/holding circuit.
7. In a typical three-wire motor control circuit, what is the purpose
of the seal-in contact?
a. To disconnect the overload relay
b. To reduce the motor's horsepower
c. To keep the contactor energized after the start button is released
d. To increase control-circuit voltage
Rationale: The seal-in contact is usually an auxiliary normally open
contact connected around the momentary start button. Once the
contactor energizes, the auxiliary contact closes and maintains the
control circuit until the stop circuit or another protective device opens
it.
8. What happens to a contactor when its coil is de-energized?
a. The contacts remain permanently closed
b. The motor automatically reverses
c. The contactor returns its contacts to their normal positions
d. The supply voltage doubles
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of an electrical control circuit?
a. To increase the available utility voltage
b. To provide mechanical support for conductors
c. To control the operation of electrical equipment
d. To eliminate the need for overcurrent protection
Rationale: A control circuit provides the signals necessary to start,
stop, sequence, regulate, or otherwise control electrical equipment. It
normally operates control devices such as relays, contactors, timers,
and sensors rather than supplying the full load power.
2. Which device is commonly used to open and close a motor power
circuit using a low-power control signal?
,a. Fuse
b. Transformer
c. Contactor
d. Receptacle
Rationale: A contactor is an electrically operated switching device
designed to control power circuits, particularly motor loads. A
relatively small control current energizes its coil, causing the main
contacts to open or close.
3. What is the purpose of a normally open pushbutton?
a. To continuously energize a circuit
b. To close the circuit only while the button is actuated
c. To protect a motor from overload
d. To reduce line voltage
Rationale: A normally open pushbutton has contacts that remain open
when the button is at rest. Pressing the button closes the contacts and
allows current to flow through the control circuit.
4. A normally closed stop pushbutton is generally used to:
a. Increase motor speed
b. Energize a heater
,c. Interrupt the control circuit when pressed
d. Measure current
Rationale: Stop pushbuttons are commonly normally closed so that
the control circuit remains complete during normal operation.
Pressing the button opens the circuit and de-energizes the controlled
equipment.
5. What is the function of a motor starter?
a. Only to measure motor voltage
b. Only to provide grounding
c. To control motor operation and provide motor overload protection
d. To convert AC to DC
Rationale: A typical motor starter combines a contactor or similar
switching device with overload protection. This arrangement permits
the motor to be started and stopped while protecting it from
sustained overload conditions.
6. What does an auxiliary contact on a contactor commonly provide?
a. Short-circuit protection for the utility service
b. A control signal or holding circuit
c. Mechanical lubrication
d. Transformer cooling
, Rationale: Auxiliary contacts are separate from the main power
contacts and are frequently used in control circuits. They can provide
electrical interlocking, status indication, or a seal-in/holding circuit.
7. In a typical three-wire motor control circuit, what is the purpose
of the seal-in contact?
a. To disconnect the overload relay
b. To reduce the motor's horsepower
c. To keep the contactor energized after the start button is released
d. To increase control-circuit voltage
Rationale: The seal-in contact is usually an auxiliary normally open
contact connected around the momentary start button. Once the
contactor energizes, the auxiliary contact closes and maintains the
control circuit until the stop circuit or another protective device opens
it.
8. What happens to a contactor when its coil is de-energized?
a. The contacts remain permanently closed
b. The motor automatically reverses
c. The contactor returns its contacts to their normal positions
d. The supply voltage doubles
