MCQ Questions on Special Machines

50. Stator Winding in the repulsion motor

(a) Improves power factor and regulated speed effectively
(b) Eliminated armature reaction
(c) Prevents hunting in the motor
(d) Provides mechanical balance [UPPCL – 2016]

51. High starting torque is required in

(a) Lathe
(b) Air blower
(c) Locomotive
(d) Centrifugal pump [UPPCL – 2016]

52. ……….. runs on AC as well as DC supply.

(a) Capacitor motor
(b) Universal motor
(c) Repulsion motor
(d) Split phase motor [UPPCL – 2016]

53. Which of the following is NOT a part of a shaded pole motor? [UPPCL 2016]

1. Centrifugal Switch
2. Capacitor
3. Commutator

(a) Only 1
(b) 1, 2 and 3
(c) Only 1 and 2
(d) Only 2

54. Select the incorrect statement.

A single phase induction motor

1. requires only 1 winding
2. can rotate in one direction only
3. is not self-starting

(a) Only 1 and 2
(b) Only 2 and 3
(c) Only 3
 (d) Only 1 and 3

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

(a) Scharge motor
(b) Hysteresis motor
(c) Shaded pole motor
(d) Capacitor run motor

56. The centrifugal switch in a single phase motor …….. of the motor. [UPPCL – 2016]

(a) Disconnects auxiliary winding
(b) Reconnects main winding
(c) Disconnects main winding
(d) Reconnects auxiliary winding

57. In a single phase AC series motor the purpose of providing compensating winding is to:

(a) Reduce heating
(b) Reduce sparking of brushes
(c) Increase the torque
(d) Minimize vibrations

58. Which of the following statements is correct for a single phase Hysteresis motor?

(a) It can run at synchronous and sub synchronous speed
(b) It can run at sub synchronous speed only
(c) It can run at synchronous and super synchronous speed
(d) It can run at synchronous speed only

59. For a stepper motor, which torque has the highest numerical value?

(a) Pull-out torque
(b) Pull-in torque
(c) Detent torque
(d) Holding torque

60. A linear servo motor must have:

(a) High rotor resistance
(b) High rotor reactance
(c) Large air gap
(d) Low rotor resistance

61. The function of a centrifugal switch in single phase induction motors is to:

(a) Protect the motor from overloading
(b) Improve the starting performance of the motor
(c) Cut off starting winding at appropriate time
(d) Cut the capacitor during running condition

62. A voltmeter gives 120 oscillation per minute, when connected to the rotor of an induction motor. The stator frequency is 50 Hz. The slope of the motor is:

(a) 2%
(b) 5%
(c) 2.5%
(d) 4%

63. In the slew range of a stepper motor, it

(a) Can start, stop and reverse as desired
(b) Cannot start but can stop and reverse on command
(c) Cannot start, stop and reverse on command
(d) Cannot start and synchronize but can reverse or command

64. In a line printer used to print the output of a computer the paper is required to be advanced by a line spacing as soon as printing of the line is over, which one of the following motors is best suited for this application?

(a) DC motor
(b) Synchronous motor
(c) Conduction motor
(d) Stepper motor

65. In which single-phase motor, the rotor has no teeth or winding?

(a) Split phase motor
(b) Repulsion motor
(c) Hysteresis motor
(d) Universal motor

66. Reluctance motors are

(a) Singly excited
(b) Doubly excited
(c) Either of the above
(d) None of the above

67. Which motor will make least noise?

(a) Hysteresis motor
(b) Capacitor motor
(c) Shaded-pole motor
(d) Universal motor

68. One among the following types of torque has the highest numerical value, in a stepper motor, identify the type. [UPPCL JE 2014]

(a) Detent torque
(b) Holding torque
(c) Dynamic torque
(d) Ripple torque

69. Which among the following statements is true regarding the angular displacement of a stepper motor? [UPPCL JE – 2014]

(a) It can be precisely controlled.
(b) It cannot be readily interfaced with micro computer based controller.
(c) It cannot be precisely controlled.
(d) It cannot be used for positioning of work tables and tools in NC machines.

70. Generally used motor in domestic food mixer is:

(a) Capacitor start motor
(b) Shaded pole motor
(c) Universal motor
(d) Reluctance motor

71. For which of the following pair of machines, the stator and its winding can be of the same type:

(a) Universal motor and stepper motor
(b) D.C. motor and hysteresis motor
(c) Hysteresis motor and reluctance motor
(d) Induction motor and D.C. motor

72. The hysteresis Motor:

(a) Has a D.C. winding on the rotor
(b) Rotor is made out of hard magnetic material
(c) Has squirrel-cage winding on the rotor
(d) Is not-self starting

73. Which single phase ac motor will you select for record players and tape recorders ?

(a) Hysteresis motor
(b) Shaded pole motor
(c) Reluctance motor
(d) Two value capacitor motor

74. AC servomotor resembles

(a) Two phase induction motor
(b) Three phase induction motor
(c) Direct current series motor
(d) Universal motor

75. Which of the following motors is most suitable for signalling devices and many kinds of timers? [DSSSB JE 2015]

(a) D.C. shunt motor
(b) D.C. series motor
(c) Induction motor
(d) Reluctance motor

76. In a four-phase variable reluctance type stepper motor, stator consist of 8 poles and rotor has 6 poles. The step angle will be:

(a) 30°
(b) 45°
(c) 15°
(d) 10° [DMRC – 2015]