,INDUSTRIAL MAINTENANCE TECHNICIAN TEST EXAM
COMPREHENSIVE PRACTICE QUESTION BANK
1. A technician measures 0 VAC across the line side of a 3-phase motor starter
contactor but reads 480 VAC at the load side when the contactor is de-energized.
What does this indicate?
A) The contactor is welded closed
B) The motor is single-phasing
C) The incoming power feed is reversed
D) The overload relay is tripped
Correct Answer: A) The contactor is welded closed
Rationale: If voltage is present on the load side when the contactor is de-energized and
the line side reads 0V, the only explanation is that the contacts are physically welded or
shorted closed, allowing backfeed. This is a dangerous condition requiring immediate
replacement.
2. In a hydraulic system, what is the direct result of setting the pressure relief valve
too low?
A) The pump will cavitate
B) The actuator will not develop sufficient force to move the load
C) The system will overheat rapidly
D) The return filter will bypass
Correct Answer: B) The actuator will not develop sufficient force to move the load
Rationale: Actuator force is a product of pressure and piston area. If the relief valve opens
before the system reaches the pressure required to overcome the load resistance, the
actuator will stall or move slowly regardless of pump flow.
3. A technician notices that a 480V motor is drawing 15% higher than nameplate
FLA. The voltage and frequency are correct. What is the most likely mechanical
cause?
A) The motor is running in reverse
,B) The driven load is increased (e.g., worn bearings in the pump, product build-up)
C) The motor leads are swapped
D) The ambient temperature is too low
Correct Answer: B) The driven load is increased (e.g., worn bearings in the pump,
product build-up)
Rationale: Motor current is directly proportional to the mechanical load. If electrical
supply is stable, a sustained current increase indicates the driven equipment is demanding
more torque, often due to mechanical degradation, product buildup, or viscosity changes.
4. What is the primary function of an anti-extrusion (back-up) ring in a hydraulic
cylinder seal assembly?
A) To provide primary sealing
B) To prevent the O-ring or seal from extruding into the clearance gap under high
pressure
C) To lubricate the cylinder rod
D) To filter the hydraulic fluid
Correct Answer: B) To prevent the O-ring or seal from extruding into the clearance
gap under high pressure
Rationale: At high pressures, soft elastomeric seals can be forced into the diametral
clearance between the piston and cylinder bore. Back-up rings, made of harder materials
like PTFE or nylon, support the seal and prevent it from extruding and failing.
5. When performing a ground fault test on a 480V motor winding using a
megohmmeter, what is considered an acceptable minimum insulation resistance
for a motor rated at 480V?
A) 0.5 Megohms
B) 1.0 Megohm
C) 5.0 Megohms
D) 100 Megohms
Correct Answer: B) 1.0 Megohm
Rationale: General industry standards (IEEE 43) suggest that for a 480V motor, insulation
resistance should be at least 1 Megohm per 1000V of operating voltage. Therefore, 0.48
, Megohms is the absolute minimum, but 1.0 Megohm is the practical accepted threshold.
Values below this indicate moisture or contamination.
6. In a pneumatic system, a cylinder is extending too quickly and slamming into
the end cap. Which component is most likely malfunctioning or misadjusted?
A) The pressure regulator
B) The speed control (flow control) valve on the extend port
C) The solenoid valve
D) The filter element
Correct Answer: B) The speed control (flow control) valve on the extend port
Rationale: Speed control valves (often with a check valve for free flow in one direction)
restrict exhaust air to control cylinder speed. If the restriction on the extend side is wide
open or defective, the cylinder will travel at full speed, causing impact and noise.
7. What does the term "slip" in a 3-phase induction motor refer to?
A) The belt slipping on the pulley
B) The difference between synchronous speed and rotor speed, expressed as a
percentage
C) The voltage drop in the stator windings
D) The mechanical play in the coupling
Correct Answer: B) The difference between synchronous speed and rotor speed,
expressed as a percentage
Rationale: Slip is essential for induction motor operation. It represents the relative motion
between the rotating magnetic field (synchronous speed) and the rotor. Without slip, no
current is induced in the rotor bars, and no torque is produced. Typical slip is 1-5%.
8. A PLC analog input card is receiving a 12mA signal from a 4-20mA pressure
transmitter. The transmitter range is 0-100 PSI. What is the pressure reading?
A) 0 PSI
B) 25 PSI
COMPREHENSIVE PRACTICE QUESTION BANK
1. A technician measures 0 VAC across the line side of a 3-phase motor starter
contactor but reads 480 VAC at the load side when the contactor is de-energized.
What does this indicate?
A) The contactor is welded closed
B) The motor is single-phasing
C) The incoming power feed is reversed
D) The overload relay is tripped
Correct Answer: A) The contactor is welded closed
Rationale: If voltage is present on the load side when the contactor is de-energized and
the line side reads 0V, the only explanation is that the contacts are physically welded or
shorted closed, allowing backfeed. This is a dangerous condition requiring immediate
replacement.
2. In a hydraulic system, what is the direct result of setting the pressure relief valve
too low?
A) The pump will cavitate
B) The actuator will not develop sufficient force to move the load
C) The system will overheat rapidly
D) The return filter will bypass
Correct Answer: B) The actuator will not develop sufficient force to move the load
Rationale: Actuator force is a product of pressure and piston area. If the relief valve opens
before the system reaches the pressure required to overcome the load resistance, the
actuator will stall or move slowly regardless of pump flow.
3. A technician notices that a 480V motor is drawing 15% higher than nameplate
FLA. The voltage and frequency are correct. What is the most likely mechanical
cause?
A) The motor is running in reverse
,B) The driven load is increased (e.g., worn bearings in the pump, product build-up)
C) The motor leads are swapped
D) The ambient temperature is too low
Correct Answer: B) The driven load is increased (e.g., worn bearings in the pump,
product build-up)
Rationale: Motor current is directly proportional to the mechanical load. If electrical
supply is stable, a sustained current increase indicates the driven equipment is demanding
more torque, often due to mechanical degradation, product buildup, or viscosity changes.
4. What is the primary function of an anti-extrusion (back-up) ring in a hydraulic
cylinder seal assembly?
A) To provide primary sealing
B) To prevent the O-ring or seal from extruding into the clearance gap under high
pressure
C) To lubricate the cylinder rod
D) To filter the hydraulic fluid
Correct Answer: B) To prevent the O-ring or seal from extruding into the clearance
gap under high pressure
Rationale: At high pressures, soft elastomeric seals can be forced into the diametral
clearance between the piston and cylinder bore. Back-up rings, made of harder materials
like PTFE or nylon, support the seal and prevent it from extruding and failing.
5. When performing a ground fault test on a 480V motor winding using a
megohmmeter, what is considered an acceptable minimum insulation resistance
for a motor rated at 480V?
A) 0.5 Megohms
B) 1.0 Megohm
C) 5.0 Megohms
D) 100 Megohms
Correct Answer: B) 1.0 Megohm
Rationale: General industry standards (IEEE 43) suggest that for a 480V motor, insulation
resistance should be at least 1 Megohm per 1000V of operating voltage. Therefore, 0.48
, Megohms is the absolute minimum, but 1.0 Megohm is the practical accepted threshold.
Values below this indicate moisture or contamination.
6. In a pneumatic system, a cylinder is extending too quickly and slamming into
the end cap. Which component is most likely malfunctioning or misadjusted?
A) The pressure regulator
B) The speed control (flow control) valve on the extend port
C) The solenoid valve
D) The filter element
Correct Answer: B) The speed control (flow control) valve on the extend port
Rationale: Speed control valves (often with a check valve for free flow in one direction)
restrict exhaust air to control cylinder speed. If the restriction on the extend side is wide
open or defective, the cylinder will travel at full speed, causing impact and noise.
7. What does the term "slip" in a 3-phase induction motor refer to?
A) The belt slipping on the pulley
B) The difference between synchronous speed and rotor speed, expressed as a
percentage
C) The voltage drop in the stator windings
D) The mechanical play in the coupling
Correct Answer: B) The difference between synchronous speed and rotor speed,
expressed as a percentage
Rationale: Slip is essential for induction motor operation. It represents the relative motion
between the rotating magnetic field (synchronous speed) and the rotor. Without slip, no
current is induced in the rotor bars, and no torque is produced. Typical slip is 1-5%.
8. A PLC analog input card is receiving a 12mA signal from a 4-20mA pressure
transmitter. The transmitter range is 0-100 PSI. What is the pressure reading?
A) 0 PSI
B) 25 PSI
