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MCQOPTIONS
This section includes 240 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
The complete circle diagram of induetion motor can be drawn with the help of datafound from |
| A. | noload test |
| B. | blocked rotor test |
| C. | stator resistance test |
| D. | all of the above |
| Answer» E. | |
| 52. |
A pump induction motor is switched on to a supply 30% lower than its rated voltage.The pump runs. What will eventually happen ? It will |
| A. | stall after sometime |
| B. | stall immediately |
| C. | continue to run at lower speed without damage |
| D. | get heated and subsequently get damaged |
| Answer» E. | |
| 53. |
A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. onfull load. The machine has 6 poles. The slip of the machine will be |
| A. | 0.01 |
| B. | 0.02 |
| C. | 0.03 |
| D. | 0.04 |
| Answer» E. | |
| 54. |
In Ns is the synchronous speed and s the slip, then actual running speed of aninduction motor will be |
| A. | Ns |
| B. | s.N, |
| C. | (l-s)Ns |
| D. | (Ns-l)s |
| Answer» D. (Ns-l)s | |
| 55. |
A 3-phase induction motor stator delta connected, is carrying full load and one of itsfuses blows out. Then the motor |
| A. | will continue running burning its one phase |
| B. | will continue running burning its two phases |
| C. | will stop and carry heavy current causing permanent damage to its winding |
| D. | will continue running without any harm to the winding |
| Answer» B. will continue running burning its two phases | |
| 56. |
5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m.Which motor will be the costliest ? |
| A. | 730 r.p.m. |
| B. | 960 r.p.m. |
| C. | 1440 r.p.m. |
| D. | 2880 r.p.m. |
| Answer» B. 960 r.p.m. | |
| 57. |
A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. willbe |
| A. | 200 Hz |
| B. | 50 Hz |
| C. | 2 Hz |
| D. | 0.2 Hz |
| Answer» D. 0.2 Hz | |
| 58. |
In squirrel cage induction motors, the rotor slots are usually given slight skew in orderto |
| A. | reduce windage losses |
| B. | reduce eddy currents |
| C. | reduce accumulation of dirt and dust |
| D. | reduce magnetic hum |
| Answer» E. | |
| 59. |
A centrifugal switch is used to dis- connect ‘starting winding when motor has___________? |
| A. | run for about 1 minute |
| B. | run for about 5 minutes |
| C. | picked up about 50 to 70 per cent of rated speed |
| D. | picked up about 10 to 25 per cent of rated speed |
| Answer» D. picked up about 10 to 25 per cent of rated speed | |
| 60. |
A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will______________? |
| A. | start and then stop |
| B. | start and run slowly |
| C. | start and run at rated speed |
| D. | not start at all |
| Answer» E. | |
| 61. |
In a capacitor start motor, the phase displacement between starting and running winding can be nearly |
| A. | 10° |
| B. | 30° |
| C. | 60° |
| D. | 90° |
| Answer» E. | |
| 62. |
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 |
| Answer» D. Universal | |
| 63. |
In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to |
| A. | improve power factor |
| B. | increase overload capacity |
| C. | reduce fluctuations in torque |
| D. | to improve torque |
| Answer» B. increase overload capacity | |
| 64. |
The range of efficiency for shaded pole motors is |
| A. | 95% to 99% |
| B. | 80% to 90% |
| C. | 50% to 75% |
| D. | 5% to 35% |
| Answer» E. | |
| 65. |
Which of the following motor will give relatively high starting torque ? |
| A. | Capacitor start motor |
| B. | Capacitor run motor |
| C. | Split phase motor |
| D. | Shaded pole motor |
| Answer» B. Capacitor run motor | |
| 66. |
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 |
| Answer» E. | |
| 67. |
A single-phase induction motor is |
| A. | inherently self-starting with high torque |
| B. | inherently self-starting with low torque |
| C. | inherently non-self-starting with low torque |
| D. | inherently non-self-starting with high torque |
| Answer» D. inherently non-self-starting with high torque | |
| 68. |
In a single phase motor the centrifugal switch |
| A. | disconnects auxiliary winding of the motor |
| B. | disconnects main winding of the motor |
| C. | reconnects the main winding the motor |
| D. | reconnects the auxiliary winding of the motor |
| Answer» B. disconnects main winding of the motor | |
| 69. |
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 |
| Answer» C. Repulsion start induction run motor | |
| 70. |
The purpose of stator winding in the compensated repulsion motor is to |
| A. | provide mechanical balance |
| B. | improve power factor and provide better speed regulation |
| C. | prevent hunting in the motor |
| D. | eliminate armature reaction |
| Answer» C. prevent hunting in the motor | |
| 71. |
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 |
| Answer» D. All of the above | |
| 72. |
Which of the following motors can be run on AC. as well as D.C. supply ? |
| A. | Universal motor |
| B. | Repulsion motor |
| C. | Synchronous motor |
| D. | Reluctance motor |
| Answer» B. Repulsion motor | |
| 73. |
Which of the following motors is used in tape-recorders ? |
| A. | Hysteresis motor |
| B. | Reluctance motor |
| C. | Capacitor-run motor |
| D. | Universal motor |
| Answer» B. Reluctance motor | |
| 74. |
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 |
| Answer» D. it is quiet in operation | |
| 75. |
The capacitors used in single-phase capacitor motors have no |
| A. | voltage rating |
| B. | dielectric medium |
| C. | polarity marking |
| D. | definite value |
| Answer» D. definite value | |
| 76. |
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 |
| Answer» D. separately excited motor | |
| 77. |
Which motor is normally free from mechanical and magnetic vibrations ? |
| A. | Split phase motor |
| B. | Universal motor |
| C. | Hysteresis motor |
| D. | Shaded pole motor |
| Answer» D. Shaded pole motor | |
| 78. |
A schrage motor can run on |
| A. | zero slip |
| B. | negative slip |
| C. | positive slip |
| D. | all of the above |
| Answer» E. | |
| 79. |
The wattage rating for a ceiling fan motor will be in the range |
| A. | 200 to 250 W |
| B. | 250 to 500 W |
| C. | 50 to 150 W |
| D. | 10 to 20 W |
| Answer» D. 10 to 20 W | |
| 80. |
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 |
| Answer» D. None of the above | |
| 81. |
Which of the following motors is used for unity power factor ? |
| A. | Hysteresis motor |
| B. | Schrage motor |
| C. | Universal motor |
| D. | Reluctance motor |
| Answer» C. Universal motor | |
| 82. |
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 |
| Answer» E. | |
| 83. |
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) |
| Answer» E. | |
| 84. |
In repulsion motor, maximum torque is developed when |
| A. | brush axis is at 45° electrical to the field axis |
| B. | brush axis coincides with the field axis |
| C. | brush axis is at 90° electrical to the field axis |
| D. | none of the above |
| Answer» B. brush axis coincides with the field axis | |
| 85. |
A repulsion motor is equipped with |
| A. | slip rings |
| B. | commutator |
| C. | both (A) and (B) |
| D. | none of the above |
| Answer» C. both (A) and (B) | |
| 86. |
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 |
| Answer» B. from shaded pole to main pole | |
| 87. |
The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it |
| A. | improves the efficiency |
| B. | helps the rotor teeth to remain under the stator teeth |
| C. | helps in reducing the tendency of the rotor teeth to remain under the stator teeth |
| D. | improves the power factor |
| Answer» D. improves the power factor | |
| 88. |
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 |
| Answer» D. run slower | |
| 89. |
In a hysteresis motor, the rotor must have |
| A. | retentivity |
| B. | resistivity |
| C. | susceptibility |
| D. | none of the above |
| Answer» B. resistivity | |
| 90. |
In capacitor start single-phase motors |
| A. | current in the starting winding leads the voltage |
| B. | current in the starting winding lags the voltage |
| C. | current in the starting winding is in phase with voltage in running winding |
| D. | none of the above |
| Answer» B. current in the starting winding lags the voltage | |
| 91. |
In a two value capacitor motor, the capacitor used for running purposes is |
| A. | air capacitor |
| B. | paper spaced oil filled type |
| C. | ceramic type |
| D. | a.c. electrolytic type |
| Answer» C. ceramic type | |
| 92. |
Which of the following motor will give the highest starting torque ? |
| A. | D.C. shunt motor |
| B. | Schrage motor |
| C. | Repulsion start and induction run motor |
| D. | Universal motor |
| Answer» C. Repulsion start and induction run motor | |
| 93. |
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 |
| Answer» E. | |
| 94. |
The rotor of a hysteresis motor is made of |
| A. | aluminium |
| B. | cast iron |
| C. | chrome steel |
| D. | copper |
| Answer» D. copper | |
| 95. |
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 |
| Answer» E. | |
| 96. |
If a particular application needs high speed and high starting torque, then which of the following motor will bepreferred ? |
| A. | Universal motor |
| B. | Shaded pole type motor |
| C. | Capacitor start motor |
| D. | Capacitor start and run motor |
| Answer» B. Shaded pole type motor | |
| 97. |
The motor used for the compressors is |
| A. | d.c. series motor |
| B. | shaded pole motor |
| C. | capacitor-start capacitor-run motor |
| D. | reluctance motor |
| Answer» D. reluctance motor | |
| 98. |
The repulsion start induction run motor is used because of |
| A. | good power factor |
| B. | high efficiency |
| C. | minimum cost |
| D. | high starting torque |
| Answer» E. | |
| 99. |
If the capacitor of a single-phase motor is short-circuited |
| A. | the motor will not start |
| B. | the motor will run |
| C. | the motor will run in reverse direction |
| D. | the motor will run in the same direction at reduced r.p.m. |
| Answer» B. the motor will run | |
| 100. |
The speed/load characteristics of a universal motor is same as that of |
| A. | D.C. motor |
| B. | D.C. shunt motor |
| C. | D.C. series motor |
| D. | none of the above |
| Answer» D. none of the above | |