MCQ in AC Motors Flashcards
Which of the following is not a reason why a single phase induction motor will not run?
A. one of the current is made out of phase between the lines
B. hysteresis
C. shaded poles
D. two windings displaced from each other
B
The following are types of AC motor starters except one
A. reactance starter
B. wye-delta starter
C. across the line starter
D. capacitance starter
C
Motor starting device that will reduce the voltage impressed at motor’s terminals during starting periods.
A. autotransformer
B. primary resistor-type
C. wye-delta starter
D. all of these
D
Basically all electric motors operate on the principle of repulsion or ______.
induction
The principle of operation of induction motor is based on ________.
rotating magnetic field
A compensator is a device that is used with alternating current motors to ______.
reduce the supply voltage during starting periods
A single-phase motor provided with a squirrel cage winding on its rotor in addition to its regular winding is called ________.
repulsion induction motor
A test used to determine the equivalent resistance of an induction motor is ________.
blocked rotor test
Rapid stopping of a motor by momentarily connecting the motor in reverse direction is called ________.
plugging
Repeated starting and stopping of a motor is referred to as ________.
jogging
An induction motor driven above synchronous speed is called ________.
induction generator
How do you call the speed of an alternating current (AC) induction motor?
Varying both the supply voltage and frequency at the same time
The best way to control the speed of an AC induction motor is by varying the _____.
both supply voltage and frequency simultaneously
A two pole, three phase motor has _____ field poles.
2
_____ refers to an AC generator.
A. Commutator
B. Motor (AC)
C. Rotor
D. Alternator
D
Series motors operated on either AC or DC are sometimes called _____.
universal motors
What does the term single-phase indicate?
one input
Kind of AC-motor, light load high load low speed.
universal motor
A two pole, one phase motor has _____ field poles.
2
Regarding the skewing of motor bars in a squirrel-cage induction motor, (SCIM) which statement is false?
A. it prevents cogging
B. it increases starting torque
C. it produces more uniform torque
D. it reduces motor ‘hum’ during its operation
B
The principle of operation of a 3-phase induction motor is most similar to that of a ________.
transformer with a shorted secondary
The magnetizing current drawn by transformers and induction motors is the cause of their ____ power factor.
zero
The effect of increasing the length of air-gap in an induction motor will be to increase the ________.
magnetizing current
