Q.1
A capacitor-start single phase induction motor is switched on to supply with itscapacitor replaced by an inductor of equivalent reactance value. It will
  • start and then stop
  • start and run slowly
  • start and run at rated speed
  • not start at all
Q.2
Burning out of windings is due to
  • short circuited capacitor
  • capacitor value hiving changed
  • open circuiting of capacitor
  • none of the above
Q.3
The electric motor used in portable drills is
  • capacitor run motor
  • hysteresis motor
  • universal motor
  • repulsion motor
Q.4
For which of the applications a reluctance motor is preferred ?
  • Electric shavers
  • Refrigerators
  • Signalling and timing devices
  • Lifts and hoists
Q.5
In A.C. series motor compensating winding is employed to
  • reduce the effects of armature reaction
  • increase the torque
  • reduce sparking at the brushes
  • none of the above
Q.6
A centrifugal switch is used to disconnect starting winding when motor has
  • run for about 1 minute
  • run for about 5 minutes
  • picked up about 50 to 70 per cent of rated speed
  • picked up about 10 to 25 per cent of rated speed
Q.7
In a A.C. series motor armature coils are usually connected to commutator
  • through resistance
  • through reactances
  • through capacitors
  • solidly
Q.8
Which of the following motors is inherently self starting ?
  • Split motor
  • Shaded-pole motor
  • Reluctance motor
  • None of these
Q.9
In which single-phase motor, the rotor has no teeth or winding ?
  • Split phase motor
  • Reluctance motor
  • Hysteresis motor
  • Universal motor
Q.10
In a shaded pole single-phase motor, the revolving field is produced by the use of
  • inductor
  • capacitor
  • resistor
  • shading coils
Q.11
Direction of rotation of a split phase motor can be reversed by reversing the connection of
  • running winding only
  • starting winding only
  • either (A) or (B)
  • both (A) and (B)
Q.12
Which of the following statements regarding reluctance-start motor is incorrect ?
  • It is similar to reluctance motor
  • It is basically an induction motor and not a synchronous one
  • So far as its basic working principle is concerned, it is similar to shaded pole motor
  • the air-gap between rotor and salient poles is non- uniform
Q.13
Which of the following statements regarding two value capacitor motor is incorrect ?
  • It is a reversing motor
  • It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
  • It has low starting as well as rushing currents
  • It has high starting torque
Q.14
Speed control of a universal motor is achieved by
  • Varying field flux with tapped field windings
  • Connecting rheostat in series
  • Applying variable voltage by means of silicon controlled rectifier
  • All of the above methods
Q.15
Torque developed by a single phase induction motor at starting is
  • pulsating
  • uniform
  • none of the above
  • nil
Q.16
The rotor developed by a single-phase motor at starting is
  • more than rated torque
  • rated torque
  • less than the rated torque
  • zero
Q.17
The speed of a universal motor is usually reduced by using
  • gearing
  • belts
  • brakes
  • chains
Q.18
The motor used on small lathes is usually
  • universal motor
  • shunt motor
  • single-phase capacitor run motor
  • 3-phase synchronous motor
Q.19
After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on
  • running winding
  • rotor winding
  • field winding
  • compensating winding
Q.20
The power factor of a single-phase induction motor is usually
  • lagging
  • always leading
  • unity
  • unity to 0.8 leading
Q.21
Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a
  • Magnetic relay
  • Thermal relay
  • Centrifugal switch
  • None of the above
Q.22
To reverse the direction of rotation of acapacitor start motor while it is running we should
  • disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
  • disconnect motor from supply and immediately reconnect it to supply with reversed con-nections of the main winding
  • reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply
  • reverse the direction of connections of the auxiliary winding and immediately connect it to supply
Q.23
A universal motor is one which
  • can be operated either on or supply at approximately the same speed and output
  • can be marketed internationally
  • runs at dangerously high speed on no-load
  • none of the above
Q.24
In a shaded pole motor, the shading coil usually consist of
  • a single turn of heavy wire which is in parallel with running winding
  • a single turn of heavy copper wire which is short-circuited and carries only induced current
  • a multilayer fine gauge copper wire in parallel with running winding
  • none of the above
Q.25
The shaded pole motor is used for
  • high starting torque
  • low starting torque
  • medium starting torque
  • very high starting torque
Q.26
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of
  • high inductance of field and armature circuits
  • induced current in rotor due to variations of flux
  • fine copper wire winding
  • none of the above
Q.27
The speed of a universal motor is generally reduced by using
  • gear trains
  • V-belts
  • brakes
  • chains
Q.28
In split-phase motor auxiliary winding is of
  • thick wire placed at the bottom of the slots
  • thick wire placed at the top of the slots
  • thin wire placed at the top of the slots
  • thin wire placed at the bottom of the slots
Q.29
In a capacitor start motor, the phase displacement between starting and running winding can be nearly
  • 10°
  • 30°
  • 60°
  • 90°
Q.30
Which of the following single-phase induction motors is generally used in time phonographs?
  • Resistance start
  • Capacitor start capacitor run
  • Shaded pole
  • Universal
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