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WorksheetsUnit 5 Review Part-1
Total questions: 53
Worksheet time: 53mins
1. The armature direction of rotation depend on______________
Magnetic field polarity & direction of current in the armature conductor
Armature motion and magnetic polarity
Direction of current and motor type
Direction of current and commutator connection
Which direction does the current-carrying conductor in a magnetic field will move around a magnetic field on a Dc motor?
Left angles to direction of field
Downward to direction of field
Right angles to direction of the field
Right angles to direction of the auxiliary winding
In Fleming’s right-hand rule, the thumb represents
Direction of magnetic field
Direction of current flow
Direction of conductor
Direction of voltage
If the polarity of the supply current for an operating DC series motor is reversed,
the armature current reversed
the armature current not reversed
Run in the opposite direction
Run in both directions
What happens if the polarity of the supply current in a DC series motor is reversed
magnetic field polarity remains the same and current direction will revers
magnetic field polarity will reverse and armature current direction is the same
both magnetic field polarity and armature current direction will reverse
both magnetic field polarity and armature current direction will remain the same
If the polarity of the supply current for an operating DC series motor is reversed, the motor will
Not run
Run in the same direction
Run in the opposite direction
Run in both directions
When the commutator changes direction of current flow in the armature The motor will
turn in the opposite direction
continue to turn in the same direction
stop turning
Nothing will happen
What happens to motor if you change the direction of current in the armature or field (but not both), of the DC motor?
a.
Will not run
Will run in the same direction
Will run in the opposite direction
Will burn
Which converts a single-phase power supply into two separate electrical phases at 90 electrical degrees apart?
Bearing
Capacitor
Running winding
Centrifugal switch
To start the single-phase motor rotation
The start winding energized the run winding de-energized
The start winding is energized
The run winding is energized
Both start and run winding is energized
To Running the single-phase motor rotation
The start winding is energized
The run winding disconnect when motor reaches running speed
Both start and run winding is energized
The start winding disconnect when motor reaches running speed
For safety, before using a capacitor, what precaution must be taken
Charged
tested
Discharged
Loose the capacitor connection.
In the single split phase motor, the start winding is___________
Inductive
Resistive
Capacitive
Reactive
In the single split phase motor, the Run windings is_______
Inductive
Resistive
Capacitive
Reactive
1. In the split phase what isolates the start winding from the circuit when the rotor reaches about 75%of the motor rotating speed?
Stator
Rotor winding
Centrifugal switch
Capacitor
What is the classification of an open motor where it has screens or grills over the opening to prevent accidental contact with hazardous parts?
guarded motor
drip-proof motor
open pipe-ventilated motor
splash-proof motor
What is the classification of an enclosed motor if it has a special cover containing cooling ducts?
totally enclosed water-cooled motor
totally enclose the non-ventilated motor
explosion-proof motor
dust-ignition proof motor
Which three-phase induction has no brushes to replace or no commutator/slip rings to service?
capacitor-start motor
wound-rotor induction motor
synchronous motor
squirrel-cage induction motor
How do you change the direction of rotation on DC motor?
revers the connection of the capacitor
change both the current flow in the armature and the magnetic field polarity
change the direction of current flow on the centrifugal switch
change the direction of current flow in the armature
Which is a disadvantage of a three-phase squirrel cage motor?
load variations do not change operating speed
speed control is difficult
it has commutator and slip ring to service
higher maintenance cost
What circulates air in the capacitor – start motor
Fan fins
End shield
Fan blade
Motor housing
In a single-phase motor, the conductor size of the run winding as compared to start winding is
Thinner
Thicker
Same size
None of these
In a split-phase motor, what is the relationship between current in start and run?
The current of the start winding leading the run winding by 90.
The current of the start winding lagging the run winding by 90.
The current of the run winding leading the start winding by 90.
The current of the start winding in the phase with the run winding
Which is a disadvantage of a three-phase wound-rotor motor?
Regularly needs new slip rings and brushes
Speed control
Overheat if frequently stopped and started
Load variations do not change the operating speed
The force on the motor that produces rotation is called
Torque
Capacitance
Compression
Induction
The 3-phase motor, which has no slip rings, brushes, or commutator is known as
Wound rotor motor
Squirrel cage motor
Capacitor start motor
Synchronous motor
The 3-phase motor has high starting torque and a variable smooth speed control known as
Wound-rotor motor
Capacitor start motor
Squirrel cage motor
Synchronous motor
The 3-phase motor which has a poor power factor at no-load and low-load conditions is known as
Wound-rotor motor
Capacitor start motor
Squirrel cage motor
Synchronous motor
The 3-phase motor with low starting torque but load variations do not change its operating speed known as
Wound-rotor motor
Capacitor start motor
Squirrel cage motor
Synchronous motor
The three-phase motor that can be used to improve and correct the power factor of a power plant system is known as
Wound-rotor motor
Capacitor start motor
Squirrel cage motor
Synchronous motor
The main advantage of the wound rotor motor is
It has a low starting torque
It requires a low maintenance cost
It has a good speed control
It doesn’t require slip rings or brushes
What type of three-phase motor that has constant speed from no-load to full load, the load variations do not change the operating speed
Squirrel cage induction motor
Wound rotor induction motor
Compound DC motor
Synchronous motor
What is the classification of an enclosed motor which is used in areas where flammable vapors present are classified as
Waterproof motor
Explosion-proof motor
Dust-ignition proof motor
Drip-proof motor
What is the classification of an enclosed motor that has cooled by air forced through a pipe or duct?
Totally enclosed non ventilated motor
Totally enclosed Pipe ventilated motor
Dust-ignition proof motor
Drip-proof motor
What is the classification of an enclosed motor has cooled by surrounding air?
Totally enclosed non ventilated motor
Totally enclosed Pipe ventilated motor
Dust-ignition proof motor
Drip-proof motor
What is the classification of an enclosed motor, designed to keep out water in the stream from a hose?
Totally enclosed non ventilated motor
Totally enclosed Pipe ventilated motor
Dust-ignition proof motor
Waterproof motor
What is the classification of an enclosed motor has a special cover containing cooling ducts?
Totally cooling enclosed non ventilated motor
Totally enclosed water-cooled motor
Totally enclosed Pipe ventilated motor
Dust-ignition proof motor
What is the classification of an open motor shown (to prevent drop of liquid or solid particles at an angle from 0 to 15?
Drip proof moto
Splash proof motor
Water proof motor
Guarded motor
What is the classification of an open motor shown (to prevent drop of liquid or solid particles at an angle from 0 to 100?
Drip proof motor
Splash proof motor
Water proof motor
Guarded motor
Which type of motors that its enclosure opening at an angle 0° to 15°?
Weather protected motor
Drip proof motor
Splash proof motor
Totally enclosed motor
Which type of motors that its enclosure opening at an angle 0° to 100°?
Weather protected motor
Drip proof motor
Splash proof motor
Totally enclosed motor
What is the classification of an open motor has designed to minimize the entrance of Rain, Snow, and dust?
Drip proof motor
Weather protected motor
Water proof motor
Guarded motor
In a capacitor-start motor, what part makes the start winding current lead the run-winding current by 90?
centrifugal switch
series winding
capacitor
shunt winding
What part of the capacitor-start motor this mechanically disconnects the starting winding from the motor’s power supply
Slots
Centrifugal switch
Shaft
Capacitor
In a capacitor-start motor, what part core where the wire is wound in coils?
Holes in the rotor
Slots in the rotor
Slots in the stator
Commutator
In a capacitor-start motor, what part is shorted by end rings completing the rotors magnetic field circuit?
Bearings
End shaft
Each bar
Mica
Which part aligns the rotor shaft and allows it to turn smoothly with little friction
Centrifugal switch
Stator slots
Bearing
Rotor bars
In a capacitor start motor, the centrifugal switch and the capacitor are connected in ____ with the start winding
Series
Parallel
Series parallel
Parallel series
What is the function of the part marked A?
keep the start winding to lead the run winding
disconnects the start winding from the power supply
align the rotor shaft and allows the rotor to turn smoothly
helps to circulate air to cool the motor
What is the function of the part marked B?
keep the start winding to lead the run winding
disconnects the start winding from the power supply
align the rotor shaft and allows the rotor to turn smoothly
helps to circulate air to cooling the motor
What is the function of the part marked C?
keep the start winding to lead the run winding
disconnects the start winding from the power supply
align the rotor shaft and allows the rotor to turn smoothly
drives the attached machines and equipment
What is the function of the part marked D?
keep the start winding to lead the run winding
disconnects the start winding from the power supply
align the rotor shaft and allows the rotor to turn smoothly
drives the attached machines and equipment
1. What part of universal motor must be properly seated for efficient operation?
filed winding
mica
end rings
brushes
