MCQ On Single Phase Induction Motor

MCQ On Single Phase Induction Motor. Multiple Choice Questions and Answers on Single phase Motors in Electrical Engineering

 

MCQ On Single Phase Induction Motor

 

Most of the fractional horsepower motors have either ?

A. hard and annealed bearings
B. ball or roller bearings
C. soft and porous bearings
D. plain or sleeve bearings

View Answer

D. plain or sleeve bearings

 

In a universal motor, the most common cause of brush sparking is ?

A. open armature winding
B. shorted armature winding
C. shorted field winding”
D. high commutator mica
E. all of the above

View Answer

E. all of the above

 

If a D.C. series motor is operated on A.C. supply, it will ?

A. spark excessively
B. have poor efficiency
C. have poor power factor
D. all of the above

View Answer

D. all of the above

 

Which of the following statements regarding reluctance-start motor is incorrect ?

A. It is similar to reluctance motor
B. It is basically an induction motor and not a synchronous one
C. So far as its basic working principle is concerned, it is similar to shaded pole motor
D. the air-gap between rotor and salient poles is non- uniform

View Answer

A. It is similar to reluctance motor

 

In a A.C. series motor armature coils are usually connected to commutator ?

A. through resistance
B. through reactances
C. through capacitors
D. solidly

View Answer

A. through resistance

 

If starting winding of a single-phase induction motor is left in the circuit, it will ?

A. run faster
B. spark at light loads
C. draw excessive current and overheat
D. run slower

View Answer

C. draw excessive current and overheat

 

If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then ?

A. motor will not come up to speed
B. motor will not carry the load
C. current drawn by the motor will be excessively high
D. electrolytic capacitor will, in all probability, suffer break down

View Answer

D. electrolytic capacitor will, in all probability, suffer break down

 

Which of the following motors has two separate windings on the motor ?

A. Repulsion motor
B. Repulsion induction motor
C. Repulsion start induction run motor
D. None of the above

View Answer

B. Repulsion induction motor

 

Which of the following statements regarding two value capacitor motor is incorrect ?

A. It is a reversing motor
B. It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
C. It has low starting as well as rushing currents
D. It has high starting torque

View Answer

B. It is preferred to permanent-split single-value capacitor motor where frequent reversals are required

 

Which of the following statements regarding a reluctance motor is incorrect ?

A. It cannot be reversed, ordinarily
B. It requires no D.C. field excitation for its operation
C. It is nothing else but a single-phase, salient pole synchronous-induction motor
D. Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor

View Answer

A. It cannot be reversed, ordinarily

 

MCQ On Single Phase Induction Motor

 

If a single phase induction motor runs slower than normal, the most likely defect is ?

A. worn bearings
B. short-circuit in the winding
C. open-circuit in the winding
D. none of the above

View Answer

A. worn bearings

 

Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners because ?

A. it is comparatively cheaper
B. it has almost non-destructible capacitor
C. it has low starting as well as running currents at relatively high power factor
D. it is quiet in operation

View Answer

C. it has low starting as well as running currents at relatively high power factor

 

To reverse the direction of rotation of a capacitor start motor while it is running we should ?

A. disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
B. disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding
C. reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply
D. reverse the direction of connections of the auxiliary winding and immediately connect it to supply

View Answer

A. disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding

 

Which of the following motors is used in tape-recorders ?

A. Hysteresis motor
B. Reluctance motor
C. Capacitor-run motor
D. Universal motor

View Answer

A. Hysteresis motor

 

In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will ?

A. become unstable
B. draw excessive armature current and may burn out
C. fall out of synchronism and come to stand still
D. run as induction motor

View Answer

D. run as induction motor

 

Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a ?

A. magnetic relay
B. thermal relay
C. centrifugal switch
D. none of the above

View Answer

A. magnetic relay

 

If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in ?

A. damage to the starting winding
B. damage to the centrifugal switch
C. overloading of running winding
D. none of the above

View Answer

A. damage to the starting winding

 

Centrifugal switch disconnects the auxiliary winding of the motor at about ______ percent of synchronous speed ?

A. 30 to 40
B. 70 to 80
C. 80 to 90
D. 100

View Answer

B. 70 to 80

 

Speed torque characteristic of a repulsion induction motor is similar to that of a D.C ?

A. shunt motor
B. series motor
C. compound motor
D. separately excited motor

View Answer

C. compound motor

 

Which of the following motors is used in a situation where load increases with speed ?

A. Induction motor
B. Three-phase series motor
C. Schrage motor
D. Hysteresis motor

View Answer

B. Three-phase series motor

 

MCQ On Single Phase Induction Motor

 

In split phase motor main winding is of ?

A. thin wire placed at the top of the slots
B. thin wire placed at the bottom of the slots
C. thick wire placed at the bottom of the slots
D. thick wire placed at the top of the” slots

View Answer

C. thick wire placed at the bottom of the slots

 

Which of the following motors is used for unity power factor ?

A. Hysteresis motor
B. Schrage motor
C. Universal motor
D. Reluctance motor

View Answer

B. Schrage motor

 

In repulsion motor, zero torque is developed when ?

A. brush axis is 45° electrical to field axis
B. brush axis coincides with the field axis
C. brush axis is 90° electrical to field axis
D. both b and c

View Answer

D. both b and c

 

Which of the following applications always have some load whenever switched on ?

A. Vacuum cleaners
B. Fan motors
C. Pistol drills
D. All of the above

View Answer

C. Pistol drills

 

In a ceilingfan employing capacitor run motor ?

A. secondary winding surrounds the primary winding
B. primary winding surrounds the secondary winding
C. both are usual arrangements
D. none of the above

View Answer

A. secondary winding surrounds the primary winding

 

The speed/load characteristics of a universal motor is same as that of ?

A. A.C. motor
B. D.C. shunt motor
C. D.C. series motor
D. none of the above

View Answer

C. D.C. series motor

 

In a hysteresis motor, the rotor must have ?

A. retentivity
B. resistivity
C. susceptibility
D. none of the above

View Answer

A. retentivity

 

Which of the following statements regarding repulsion-start induction motor is incorrect ?

A. It requires more maintenance of commutator and other mechanical devices
B. It makes quite a bit of noise on starting
C. In fractional horse power motors, it has replaced the capacitor motors
D. It is not easily reversed

View Answer

C. In fractional horse power motors, it has replaced the capacitor motors

 

As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for ?

A. fans
B. blowers
C. sound equipment
D. mixer grinders

View Answer

C. sound equipment

 

After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on ?

A. running winding
B. rotor winding
C. field winding
D. compensating winding

View Answer

A. running winding

 

MCQ On Single Phase Induction Motor

 

The direction of rotation of universal motor can be reversed the by reversing the flow of current through ?

A. armature winding
B. field winding
C. either armature winding or field winding
D. none of the above

View Answer

C. either armature winding or field winding

 

When a D.C. series motor is connected to A.C. supply, the power factor will be low because of ?

A. high inductance of field and armature circuits
B. induced current in rotor due to variations of flux
C. fine copper wire winding
D. none of the above

View Answer

A. high inductance of field and armature circuits

 

Hysteresis motor is particularly useful for high-quality record players and tape-recorders because ?

A. it revolves synchronously
B. it is not subject to any magnetic or mechanical vibrations
C. it can be easily manufactured in extremely small sizes of up to 1 W output
D. it develops hysteresis torque which is extremely steady both in amplitude and phase

View Answer

D. it develops hysteresis torque which is extremely steady both in amplitude and phase

 

Which of the following statements regarding single-phase induction motors correct ?

A. It requires only one winding
B. It can rotate in one direction only
C. It is self-starting
D. It is not self-starting

View Answer

D. It is not self-starting

 

The speed of a universal motor is generally reduced by using ?

A. gear trains
B. V-belts
C. brakes
D. chains

View Answer

A. gear trains

 

Which of the following single-phase motors has relatively poor starting torque ?

A. Universal motor
B. Repulsion motor
C. Capacitor motor
D. All single phase motors have zero starting torque

View Answer

C. Capacitor motor

 

Which of the following statements regarding hysteresis motor is in incorrect ?

A. It is extremely sensitive to fluctuations in supply voltage
B. Its high starting torque is due to its high rotor hysteresis loss
C. It is extremely quiet in operation
D. It accelerates from rest to full-speed almost instantaneously

View Answer

A. It is extremely sensitive to fluctuations in supply voltage

 

Which of the following motors can be used for unity power factor ?

A. Capacitor run motor
B. Shaded pole motor
C. Hysteresis motor
D. Schrage motor

View Answer

D. Schrage motor

 

The speed of a universal motor is usually reduced by using ?

A. gearing
B. belts
C. brakes
D. chains

View Answer

A. gearing

 

The wattage of motor for driving domestic sewing machine will be around ?

A. 100 to 150 W
B. 40 to 75 W
C. 10 to 30 W
D. 5 to 10 W

View Answer

A. 100 to 150 W

 

MCQ On Single Phase Induction Motor

 

In case of high speed universal motor which of the following needs more attention ?

A. End play
B. Air gap
C. Insulation in rotor
D. Balancing of rotor

View Answer

D. Balancing of rotor

 

Which of the following single-phase motors is suitable for timing and control purposes ?

A. Reluctance motor
B. Series motor
C. Repulsion motor
D. Universal motor

View Answer

A. Reluctance motor

 

In case of a shaded pole motor the direction of rotation of the motor is ?

A. from main pole to shaded pole
B. from shaded pole to main pole
C. either of the above depending on voltage
D. either of the above depending on power factor

View Answer

A. from main pole to shaded pole

 

Which of the following single-phase induction motors is generally used in time phonographs ?

A. Resistance start
B. Capacitor start capacitor run
C. Shaded pole
D. Universal

View Answer

C. Shaded pole

 

Which of the following motors is preferred for tape-recorders ?

A. Shaded pole motor
B. Hysteresis motor
C. Two value capacitor motor
D. Universal motor

View Answer

B. Hysteresis motor

 

For which of the applications a reluctance motor is preferred ?

A. Electric shavers
B. Refrigerators
C. Signalling and timing devices
D. Lifts and hoists

View Answer

C. Signalling and timing devices

 

In A.C. series motor compensating winding is employed to ?

A. reduce the effects of armature reaction
B. increase the torque
C. reduce sparking at the brushes
D. none of the above

View Answer

C. reduce sparking at the brushes

 

The direction of rotation of an hysteresis motor is determined by ?

A. interchanging the supply leads
B. position of shaded pole with respect to main pole
C. retentivity of the rotor material
D. none of these

View Answer

B. position of shaded pole with respect to main pole

 

Which of the following motors is used in mixies ?

A. Repulsion motor
B. Reluctance motor
C. Hysteresis motor
D. Universal motor

View Answer

D. Universal motor

 

The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be ?

A. at the end connections
B. at the end terminals
C. anywhere on the winding inside a slot
D. at the slot edge where coil enters or comes out of the slot

View Answer

D. at the slot edge where coil enters or comes out of the slot

 

MCQ On Single Phase Induction Motor

 

Short-circuiter is used in ?

A. repulsion induction motor
B. repulsion motor
C. repulsion start induction run motor
D. none of the above

View Answer

C. repulsion start induction run motor

 

Burning out of winding is due to ?

A. short circuited capacitor
B. capacitor value hiving changed
C. open circuiting of capacitor
D. none of the above

View Answer

A. short circuited capacitor

 

In a shaded pole single-phase motor, the revolving field is produced by the use of ?

A. inductor
B. capacitor
C. resistor
D. shading coils

View Answer

D. shading coils

 

Direction of rotation of a split phase motor can be reversed by reversing the connection of ?

A. running winding only
B. starting winding only
C. either A. or (b)
D. both A. and (b)

View Answer

C. either A. or (b)

 

If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ?

A. Universal motor
B. Shaded pole type motor
C. Capacitor start motor
D. Capacitor start and run motor

View Answer

A. Universal motor

 

Which of the following motors is inherently self starting ?

A. Split motor
B. Shaded-pole motor
C. Reluctance motor
D. None of these

View Answer

B. Shaded-pole motor

 

In a shaded pole motor, the shading coil usually consist of ?

A. a single turn of heavy wire which is in parallel with running winding
B. a single turn of heavy copper wire which is short-circuited and carries only induced current
C. a multilayer fine gauge copper wire in parallel with running winding
D. none of the above

View Answer

B. a single turn of heavy copper wire which is short-circuited and carries only induced current

 

The rotor developed by a single-phase motor at starting is ?

A. more than i.he rated torque
B. rated torque
C. less than the rated torque
D. zero

View Answer

D. zero

 

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