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"3 phase TPC" Questions with Detailed Verified Answers
Induction motors can be connected directly across the line on starting. However, the starting
current may be ____________ the rated (running) current. Ans: ✓ ✓ ✓ four to nine times
To ensure that three-phase motor control equipment is in good operating condition, you should
Ans: ✓ ✓ ✓ maintain a regular plan of inspections
When removing grease and oil from a motor, you should avoid using too much solvent because it
Ans: ✓ ✓ ✓ can damage the insulation
200°F (95°C) is the Ans: ✓ ✓ ✓ maximum temperature at which bearings may be safely operated
Acceptable methods of cleaning insulation in auxiliary generating equipment include wiping it with
a clean cloth, blowing it off with low-pressure air, using a vacuum cleaner, and cleaning it with a(n)
Ans: ✓ ✓ ✓ approved solvent
n automatic transfer system installations that back up critical electronic gear, action is initiated
when the potential difference of any phase drops near ____________%. Ans: ✓ ✓ ✓ 90
A four-pole, three-phase motor has _____ coils. Ans: ✓ ✓ ✓ twelve
In general, the power factor of an induction motor increases with the load until the maximum
power factor is reached at Ans: ✓ ✓ ✓ full load
With a low dc field current, the ac current Ans: ✓ ✓ ✓ lags the potential difference
A synchronous motor using an amortisseur winding for starting is electrically the same as a
____________ motor Ans: ✓ ✓ ✓ squirrel-cage induction
In a cascade system having large air-gap circuit- breakers, there should not be more than _____
cascade step(s). Ans: ✓ ✓ ✓ two
A relay with inverse-time characteristics operates Ans: ✓ ✓ ✓ faster as the current increases
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Wound-rotor motors are used most often in applications that require high starting torque and low
starting current, where the driven machine starts Ans: ✓ ✓ ✓ slowly
In a squirrel-cage induction motor, motor conductor bars inserted in the slots of the rotor core are
not insulated from the core because the voltage across each bar is seldom more than ________ V.
Ans: ✓ ✓ ✓ 10
Many electric motors are manufactured as dual-voltage three-phase motors that are either Y or
delta connected with ____________ of twelve leads brought out. Ans: ✓ ✓ ✓ nine
Variable-torque motors are designed to give Ans: ✓ ✓ ✓ an increase in torque with an increase in
speed
Which of the following is true of a reactor starter, as compared to a resistance starter? Ans: ✓ ✓ ✓
Its connections are the same except that it uses induction coils
To prevent motor starter "chatter" on some motor starter circuits, it may be necessary to employ
surge and backspin protection for motors that operate Ans: ✓ ✓ ✓ pumps
If the load driven by an alternator is purely inductive, the current Ans: ✓ ✓ ✓ lags the potential
difference
The supply winding in an alternator Ans: ✓ ✓ ✓ can be part of either the rotor or the stator
A four-pole, three-phase motor has _____ coils. Ans: ✓ ✓ ✓ twelve
If an induction motor ran at synchronous speed, it would develop zero torque because of the lack of
Ans: ✓ ✓ ✓ slip
When considering power factor, remember that the induction motor is electrically equivalent to a
____________ with a short-circuited secondary winding. Ans: ✓ ✓ ✓ transformer
In an induction motor, maximum torque is always developed when the Ans: ✓ ✓ ✓ reactance and
the resistance of the rotor are equal
The winding in a squirrel-cage rotor consists of copper or aluminum bars, pressed into slots and
____________ at both ends of the rotor. Ans: ✓ ✓ ✓ Short Circuited
In establishing a schedule for inspecting generators, you should match the schedule to the
maintenance schedule of the Ans: ✓ ✓ ✓ prime mover
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"3 phase TPC" Questions with Detailed Verified Answers
Induction motors can be connected directly across the line on starting. However, the starting
current may be ____________ the rated (running) current. Ans: ✓ ✓ ✓ four to nine times
To ensure that three-phase motor control equipment is in good operating condition, you should
Ans: ✓ ✓ ✓ maintain a regular plan of inspections
When removing grease and oil from a motor, you should avoid using too much solvent because it
Ans: ✓ ✓ ✓ can damage the insulation
200°F (95°C) is the Ans: ✓ ✓ ✓ maximum temperature at which bearings may be safely operated
Acceptable methods of cleaning insulation in auxiliary generating equipment include wiping it with
a clean cloth, blowing it off with low-pressure air, using a vacuum cleaner, and cleaning it with a(n)
Ans: ✓ ✓ ✓ approved solvent
n automatic transfer system installations that back up critical electronic gear, action is initiated
when the potential difference of any phase drops near ____________%. Ans: ✓ ✓ ✓ 90
A four-pole, three-phase motor has _____ coils. Ans: ✓ ✓ ✓ twelve
In general, the power factor of an induction motor increases with the load until the maximum
power factor is reached at Ans: ✓ ✓ ✓ full load
With a low dc field current, the ac current Ans: ✓ ✓ ✓ lags the potential difference
A synchronous motor using an amortisseur winding for starting is electrically the same as a
____________ motor Ans: ✓ ✓ ✓ squirrel-cage induction
In a cascade system having large air-gap circuit- breakers, there should not be more than _____
cascade step(s). Ans: ✓ ✓ ✓ two
A relay with inverse-time characteristics operates Ans: ✓ ✓ ✓ faster as the current increases
© Get it right 2025 Getaway - Stuvia US All rights reserved
, Click here for more: Scholars nexus
Wound-rotor motors are used most often in applications that require high starting torque and low
starting current, where the driven machine starts Ans: ✓ ✓ ✓ slowly
In a squirrel-cage induction motor, motor conductor bars inserted in the slots of the rotor core are
not insulated from the core because the voltage across each bar is seldom more than ________ V.
Ans: ✓ ✓ ✓ 10
Many electric motors are manufactured as dual-voltage three-phase motors that are either Y or
delta connected with ____________ of twelve leads brought out. Ans: ✓ ✓ ✓ nine
Variable-torque motors are designed to give Ans: ✓ ✓ ✓ an increase in torque with an increase in
speed
Which of the following is true of a reactor starter, as compared to a resistance starter? Ans: ✓ ✓ ✓
Its connections are the same except that it uses induction coils
To prevent motor starter "chatter" on some motor starter circuits, it may be necessary to employ
surge and backspin protection for motors that operate Ans: ✓ ✓ ✓ pumps
If the load driven by an alternator is purely inductive, the current Ans: ✓ ✓ ✓ lags the potential
difference
The supply winding in an alternator Ans: ✓ ✓ ✓ can be part of either the rotor or the stator
A four-pole, three-phase motor has _____ coils. Ans: ✓ ✓ ✓ twelve
If an induction motor ran at synchronous speed, it would develop zero torque because of the lack of
Ans: ✓ ✓ ✓ slip
When considering power factor, remember that the induction motor is electrically equivalent to a
____________ with a short-circuited secondary winding. Ans: ✓ ✓ ✓ transformer
In an induction motor, maximum torque is always developed when the Ans: ✓ ✓ ✓ reactance and
the resistance of the rotor are equal
The winding in a squirrel-cage rotor consists of copper or aluminum bars, pressed into slots and
____________ at both ends of the rotor. Ans: ✓ ✓ ✓ Short Circuited
In establishing a schedule for inspecting generators, you should match the schedule to the
maintenance schedule of the Ans: ✓ ✓ ✓ prime mover
© Get it right 2025 Getaway - Stuvia US All rights reserved
