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Industrial Maintenance Technician Test
EXAM QUESTIONS |FREQUENTLY TESTED
QUESTIONS WITH|VERIFIED SOLUTIONS
(100% CORRECT)
1. A three-phase induction motor draws excessive current and
trips the overload relay. The most likely cause is:
A) Low voltage supply
B) Open rotor bar
C) Excessive mechanical load
D) Wrong rotation
Correct Answer: C
Rationale: Excessive load increases stator current. Low voltage
also increases current, but the most direct cause is mechanical
overload.
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2. When measuring insulation resistance of a de-energized
480V motor winding with a megger, you read 0.2 MΩ. This
indicates:
A) Good insulation
B) Shorted winding turn-to-turn
C) Ground fault
D) Open winding
Correct Answer: C
*Rationale: Minimum acceptable insulation resistance is
typically 1 MΩ + 1 MΩ/kV (≈1.5 MΩ for 480V). 0.2 MΩ
indicates insulation breakdown to ground.*
3. A technician replaces a 3-phase contactor with one of the
same coil voltage but higher contact current rating. What will
happen?
A) Premature coil failure
B) No problem – acceptable
C) Reduced motor speed
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D) Contact chatter
Correct Answer: B
Rationale: Higher contact rating is fine as long as coil voltage
matches. Current rating can be higher without issue.
4. (Scenario) A conveyor motor starts, runs for 5 seconds, then
stops. The start button works again immediately. The overload
relay is not tripped. What is the likely issue?
A) Auxiliary contact on starter not sealing
B) Low voltage
C) Open fuse in control circuit
D) Motor bearing seizure
Correct Answer: A
Rationale: Starter pulls in but drops out when start button
released – indicates missing or faulty seal-in (holding) contact.
5. A 480V motor nameplate FLA is 34A. During operation, it
draws 28A. This means:
A) Motor is underloaded
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B) Motor is overloaded
C) Voltage is too high
D) Winding is shorted
Correct Answer: A
Rationale: Actual current less than FLA indicates underloading,
which is generally acceptable but inefficient.
6. The device specifically used to protect a motor from
overheating due to prolonged overcurrent is:
A) Circuit breaker
B) Overload relay
C) Fuse
D) Contactor
Correct Answer: B
Rationale: Overload relays simulate motor heating; circuit
breakers and fuses protect against short circuits.
7. (Scenario) A technician measures 120V from L1 to ground,
120V from L2 to ground, but 0V between L1 and L2. This
Industrial Maintenance Technician Test
EXAM QUESTIONS |FREQUENTLY TESTED
QUESTIONS WITH|VERIFIED SOLUTIONS
(100% CORRECT)
1. A three-phase induction motor draws excessive current and
trips the overload relay. The most likely cause is:
A) Low voltage supply
B) Open rotor bar
C) Excessive mechanical load
D) Wrong rotation
Correct Answer: C
Rationale: Excessive load increases stator current. Low voltage
also increases current, but the most direct cause is mechanical
overload.
,Page 2 of 164
2. When measuring insulation resistance of a de-energized
480V motor winding with a megger, you read 0.2 MΩ. This
indicates:
A) Good insulation
B) Shorted winding turn-to-turn
C) Ground fault
D) Open winding
Correct Answer: C
*Rationale: Minimum acceptable insulation resistance is
typically 1 MΩ + 1 MΩ/kV (≈1.5 MΩ for 480V). 0.2 MΩ
indicates insulation breakdown to ground.*
3. A technician replaces a 3-phase contactor with one of the
same coil voltage but higher contact current rating. What will
happen?
A) Premature coil failure
B) No problem – acceptable
C) Reduced motor speed
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D) Contact chatter
Correct Answer: B
Rationale: Higher contact rating is fine as long as coil voltage
matches. Current rating can be higher without issue.
4. (Scenario) A conveyor motor starts, runs for 5 seconds, then
stops. The start button works again immediately. The overload
relay is not tripped. What is the likely issue?
A) Auxiliary contact on starter not sealing
B) Low voltage
C) Open fuse in control circuit
D) Motor bearing seizure
Correct Answer: A
Rationale: Starter pulls in but drops out when start button
released – indicates missing or faulty seal-in (holding) contact.
5. A 480V motor nameplate FLA is 34A. During operation, it
draws 28A. This means:
A) Motor is underloaded
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B) Motor is overloaded
C) Voltage is too high
D) Winding is shorted
Correct Answer: A
Rationale: Actual current less than FLA indicates underloading,
which is generally acceptable but inefficient.
6. The device specifically used to protect a motor from
overheating due to prolonged overcurrent is:
A) Circuit breaker
B) Overload relay
C) Fuse
D) Contactor
Correct Answer: B
Rationale: Overload relays simulate motor heating; circuit
breakers and fuses protect against short circuits.
7. (Scenario) A technician measures 120V from L1 to ground,
120V from L2 to ground, but 0V between L1 and L2. This
