ONLINE MCQ-Single Phase Motors Part Two

Single Phase Motors Part Two

Instructions: Click the answer button to see the correct answer.

  1. Which of the following applications would need the smallest size of motor ?
    1. Table fan
    2. Domestic motor
    3. Electric clock
    4. Sewing machine.

    Answerc

  2. All single phase ac motors are designed to operate usually on
    1. 220 V only
    2. 220 ± 0 V
    3. 220V + 10V
    4. 220 ± 10% volts.

    Answerd

  3. All single phase ac motors are designed usually to operate on the frequency
    1. 50. ± 5 Hz.
    2. 50 ± 0.5 Hz
    3. 50 ±1 Hz
    4. 50 Hz

    Answera

  4. When a dc series motor is connected to ac supply, it will
    1. all of these
    2. run on poor power factor
    3. spark excessively
    4. give poor efficiency

    Answera

  5. The torque-speed characteristic of a repulsion motor resembles that of which of the following dc motor ?
    1. separately excited motor
    2. shunt motor
    3. series is motor
    4. compound motor.

    Answerd

  6. In a single phase capacitor motor the direction of rotation will be in the opposite direction to the original when
    1. two capacitors of equal value are used
    2. capacitor is replaced by a resistance
    3. capacitor is replaced by an inductor.
    4. electrolytic capacitor is replaced by paper capacitor

    Answerc

  7. In a hysteresis motor, the position of shaded pole with respect to main pole determines
    1. hysteresis loss
    2. speed of motor
    3. no load rpm.
    4. direction of rotation

    Answerd

  8. In a shaded pole motor, the direction of rotation is from
    1. shaded pole to main pole
    2. main pole to shaded pole
    3. none of these
    4. depends on supply line polarity.

    Answerb

  9. In a shaded pole motor, shading coils are used to
    1. produce rotating magnetic field
    2. reduce friction losses
    3. reduce windage losses
    4. to protect against sparking.

    Answera

  10. In a shaded pole motor, the locked rotor current is
    1. less than the full load current.
    2. slightly more than the full load current
    3. 10 times the full load current
    4. 4 to 5 times the full load current

    Answerb

  11. Shaded pole motors are not provided with
    1. commutator
    2. centrifugal switch
    3. capacitor
    4. all of these

    Answerd

  12. In a universal motor, normally the ratio of width of brush to the width of commutator segments is
    1. 1:1
    2. 1:2
    3. 2:1
    4. 4:1.

    Answerc

  13. For a given output and speed, a universal motor as compared to 220 V, 50 Hz supply will require
    1. high voltage at high frequency
    2. less voltage at high frequency
    3. less voltage at low frequency
    4. high voltage at low frequency.

    Answerc

  14. The rotor of which motor does not have winding on it ?
    1. Universal motor
    2. Reluctance motor
    3. Hysteresis motor
    4. Repulsion motor.

    Answerc

  15. Which motor has unsymmetrical rotor ?
    1. Shaded pole motor
    2. Reluctance motor.
    3. Split-phase motor
    4. Universal motor

    Answerb

  16. If a single phase motor runs slow, the probable case may be
    1. low voltage
    2. low frequency
    3. overload
    4. any of these

    Answerd

  17. A single phase capacitor start motor will take starting current nearly
    1. three times the full load current
    2. same as full load current
    3. twice the full load current
    4. four the six times the full load current.

    Answerc

  18. Which motor will make least noise ?
    1. Hysteresis motor.
    2. Capacitor motor
    3. Shaded pole motor
    4. Universal motor

    Answera

  19. If a single phase motor runs hot the probable cause cannot be
    1. blown fuses
    2. high voltage
    3. low voltage.
    4. shorted stator coils

    Answera

  20. A single phase capacitor run motor will have starting torque as
    1. 1/2 of full load torque
    2. 1 1/2 times full load torque
    3. 2 times full load torque.
    4. same as full load torque

    Answerb

  21. Which of the following single phase motors will be cheapest ?
    1. Capacitor run motor
    2. Capacitor start motor
    3. Reluctance motor
    4. All have same cost.

    Answerb

  22. Noise in an electric motor may be due to
    1. cooling air
    2. bearings
    3. magnetic effects
    4. all of these

    Answerd

  23. For a system involving sound recording and reproduction which motor would you select ?
    1. Shaded pole motor
    2. Reluctance motor.
    3. Hysteresis motor
    4. Universal motor

    Answerc

  24. Cranes and hoists offer which type of load ?
    1. reversing,heavy start
    2. reversing, no load start
    3. non-reversing, heavy start
    4. non-reversing, no load start

    Answera

  25. Which motor is relatively free from mechanical and magnetic vibrations?
    1. Universal motor
    2. Shaded pole motor.
    3. Reluctance motor
    4. Hysteresis motor

    Answerd

  26. Which of the following motors does not have constant speed characteristics ?
    1. Reluctance motor
    2. Universal motor
    3. all of these
    4. Hysteresis motor

    Answerb

  27. For the same rating which motor has the highest starting torque ?
    1. Split phase motor
    2. Universal motor
    3. Synchronous motor
    4. All have identical starting torque.

    Answerb

  28. A capacitor selected for capacitor-run motor should be rated for
    1. average voltage.
    2. peak voltage
    3. all of these
    4. rms voltage

    Answerb

  29. If a single phase motor fails to start, the probable cause may be
    1. open in main winding
    2. any of these
    3. blown fuses
    4. open in auxiliary winding

    Answerb

  30. The reluctance torque in a motor is present when the reluctance seen by
    1. none of these
    2. rotor mmf remains constant
    3. stator mmf is constant.
    4. rotor mmf varies

    Answerd

  31. Which single phase motor has relatively high power factor ?
    1. Universal motor
    2. Synchronous motor.
    3. Repulsion motor
    4. Split phase motor

    Answera

  32. Which motor would you select for vacuum cleaners ?
    1. Hysteresis motor
    2. Universal motor
    3. Repulsion motor
    4. Reluctance motor.

    Answerb

  33. If the ceiling fan, when switched on, runs at slow speed in the reverse direction, it can be concluded that
    1. winding has burnt out
    2. capacitor is ineffective
    3. bearings are worn out
    4. none of these

    Answerb

  34. For how many poles is a split-phase motor wound if it operates at 1750 rpm at full load from a 60 Hz source ?
    1. 4 poles
    2. 6 poles
    3. 12 poles
    4. 2 poles

    Answera

  35. Which of the following capacitor-start split phase motor will have the largest value of capacitance ?
    1. 1/8 HP, 3450 rpm
    2. 3/4 HP, 1140 rpm.
    3. 1/2 HP, 1140 rpm
    4. 1/4 HP, 1725 rpm

    Answerb

  36. The speed of a split phase induction motor can be reversed by reversing the leads of
    1. main winding
    2. either of auxiliary winding or main winding
    3. speed cannot be reversed.
    4. auxiliary winding

    Answerd

  37. capacitor
    start type single phase induction motor has its capacitor replaced by
    an inductor of equivalent reluctance value.If the motor is now switched
    on to the supply, it will

    1. run in the reverse direction
    2. not run
    3. start but not take the load.
    4. run with more noise and low torque

    Answerb

  38. In ac series motor the purpose of providing compensating winding is to
    1. reduce sparking at brushes
    2. increase the torque
    3. reduce heating of armature
    4. minimize vibrations.

    Answera

  39. Which of the following is used on single phase hermetic motors ?
    1. Current coil
    2. Voltage coil
    3. All of the above.
    4. Hot wire

    Answerb

  40. Normally,
    the auxiliary winding in a single phase induction motor is cut off when
    the motor reaches a certain speed except in case of

    1. shaded pole motor
    2. split phase motor.
    3. capacitor start motor
    4. capacitor start, capacitor run motor

    Answerd

  41. In case of a reluctance motor, when the. load is increased so that it cannot maintain synchronous speed the motor will
    1. become unstable
    2. run as induction motor
    3. fall out of synchronism and come to stand still
    4. draw excessive armature current and may burn out.

    Answerb

  42. Most important characteristics of a single phase motor is
    1. that it is self-starting
    2. that it requires only one winding
    3. that it is not self-starting
    4. all of these

    Answerc

  43. In a capacitor start induction motor, the stalling torque is directly related to angle a between the 2 winding currents by
    1. cos α
    2. tan α
    3. sin α
    4. secα.

    Answerc

  44. In a capacitor start motor, the capacitor is connected in series with
    1. none of these
    2. running winding
    3. starting winding
    4. compensating winding

    Answerc

  45. The capacitor used for running purpose in a two-capacitor motor is
    1. Paper spaced oil-filled type
    2. Ceramic capacitor
    3. Air capacitor
    4. None of these

    Answera

  46. In split phase motor,
    1. main winding has low resistance and high reactance
    2. main winding has low resistance and low reactance
    3. None of these
    4. main winding has high resistance and high reactance

    Answera

  47. A single phase motor has
    1. Low starting torque
    2. High starting torque
    3. none of these
    4. Zero starling torque

    Answerd

  48. In a single phase motor, phase splitting can be done
    1. with an auxiliary winding in series with a capacitor
    2. with an auxiliary winding of high resistance
    3. with an auxiliary winding of low reactance
    4. by any of these three methods.

    Answerd

  49. A single phase self-starting motor has two stator windings
    1. which are placed at 90 and fed out of phase
    2. none of these
    3. which are placed at 90 and fed in phase
    4. which are placed at 45 and fed out of phase

    Answera

  50. In a single phase hysteresis motor, starting torque is caused by
    1. Both eddy current and hysteresis
    2. none of these
    3. Eddy current
    4. Hysteresis

    Answerc

  51. A two value capacitor motor when compared to a capacitor start has
    1. Higher starting torque and lower running power factor
    2. none of these
    3. same starting torque and improved running power factor
    4. Higher starting torque and higher running power factor

    Answerc

  52. Single phase induction motor can be made self starting by
    1. all of these
    2. adding an auxiliary winding in series with a capacitor and the main winding.
    3. adding an auxiliary winding in parallel with the main winding
    4. adding series combination of a capacitor and auxiliary winding in parallel with the main winding

    Answerd

  53. The following motor is popularly used in driving a refrigerator
    1. plain cage induction motor
    2. universal motor
    3. squirrel cage induction motor.
    4. d.c. shunt motor

    Answerb

  54. Speed of a repulsion motor at no load is
    1. low
    2. very low
    3. high
    4. dangerously high.

    Answerd

  55. Operation of a hysteresis motor can be explained on the basis of
    1. continuously revolving magnetic flux
    2. pulsating magnetic flux
    3. cross field theory
    4. intermittently revolving magnetic flux.

    Answerd

  56. The main reason of using a hysteresis motor , for high quality tape recorders and record players is that
    1. its speed is constant (synchronous)
    2. its operation is not affected by mechanical vibrations.
    3. it develops extremely steady torque
    4. it requires no centrifugal switch

    Answera

  57. A
    fluctuating voltage supply is detrimental to a refrigerator motor, but
    not to a ceiling fan motor, although both are single-phase induction
    motors because, the refrigerator motor

    1. is enclosed in a sealed unit while the fan motor is open to the environment
    2. load is constant, but the fan motor load is voltage dependent.
    3. is made more robust than the fan moto
    4. is subjected to short duty cycle but the fan motor is subjected to continuous duty

    Answera

Copyright (C) 2016 by (ALL EXAM REVIEW ADDA )

GENERAL HINDI(सामान्य हिन्दी)-MCQ1
New India Assurance Recruitment 2016 – Apply Online for 300 Administrative Officer Posts

2 Comments

  1. Dev October 6, 2018
    • Harikesh Yadav October 8, 2018

Leave a Reply