MCQOPTIONS
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MCQOPTIONS
This section includes 165 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. |
An induction motor is |
| A. | elf-starting with zero torque |
| B. | elf-starting with high torque |
| C. | elf-starting with low torque |
| D. | on-self starting |
| Answer» D. on-self starting | |
| 52. |
In case of the induction motors the torque is |
| A. | nversely proportional to (V-slip) |
| B. | irectly proportional to (slip)2 |
| C. | nversely proportional to slip |
| D. | irectly proportional to slip |
| Answer» E. | |
| 53. |
Temperature of the stator winding of a three phase induction motor is obtained by |
| A. | esistance rise method |
| B. | hermometer method |
| C. | mbedded temperature method |
| D. | ll above methods |
| Answer» E. | |
| 54. |
For driving high inertia loads best type of induction motor suggested is |
| A. | lip ring type |
| B. | quirrel-cage type |
| C. | ny of the above |
| D. | one of the above |
| Answer» B. quirrel-cage type | |
| 55. |
In case the air gap in an induction motor is increased |
| A. | he magnetizing current of the rotor will decrease |
| B. | he power factor will decrease |
| C. | peed of motor will increase |
| D. | he windage losses will increase |
| Answer» C. peed of motor will increase | |
| 56. |
For which motor the speed can be controlled from rotor side? |
| A. | quirrel-cage induction motor |
| B. | lip-ring induction motor |
| C. | oth (A) and (B) |
| D. | one of the above |
| Answer» C. oth (A) and (B) | |
| 57. |
Lubricant used for ball bearing is usually |
| A. | raphite |
| B. | rease |
| C. | ineral oil |
| D. | olasses |
| Answer» C. ineral oil | |
| 58. |
If a 3-phase supply is given to the stator and rotor is short circuited rotor will move |
| A. | n the opposite direction as the direction of the rotating field |
| B. | n the same direction as the direction of the field |
| C. | n any direction depending upon phase sequence of supply |
| D. | one of these |
| Answer» C. n any direction depending upon phase sequence of supply | |
| 59. |
The stating torque of the slip ring induction motor can be increased by adding |
| A. | xternal inductance to the rotor |
| B. | xternal resistance to the rotor |
| C. | xternal capacitance to the rotor |
| D. | oth resistance and inductance to rotor |
| Answer» C. xternal capacitance to the rotor | |
| 60. |
Rotor rheostat control method of speed control is used for |
| A. | quirrel-cage induction motors only |
| B. | lip ring induction motors only |
| C. | oth (A) and (B) |
| D. | one of the above |
| Answer» C. oth (A) and (B) | |
| 61. |
The starting torque of a three phase induction motor can be increased by |
| A. | ncreasing slip |
| B. | ncreasing current |
| C. | oth (A) and (B) |
| D. | one of the above |
| Answer» D. one of the above | |
| 62. |
The efficiency of an induction motor can be expected to be nearly~! |
| A. | 60 to 90 % |
| B. | 80 to 90 % |
| C. | 95 to 98 % |
| D. | 99 % |
| Answer» C. 95 to 98 % | |
| 63. |
The torque developed in the cage induction motor with auto-starter is~! |
| A. | k/torque with direct switching |
| B. | K √ó torque with direct switching |
| C. | K2 √ó torque with direct switching |
| D. | k2/torque with direct switching |
| Answer» D. k2/torque with direct switching | |
| 64. |
The stating torque of the slip ring induction motor can be increased by adding%! |
| A. | External inductance to the rotor |
| B. | External resistance to the rotor |
| C. | External capacitance to the rotor |
| D. | Both resistance and inductance to rotor |
| Answer» C. External capacitance to the rotor | |
| 65. |
The frame of an induction motor is usually made of%! |
| A. | Silicon steel |
| B. | Cast iron |
| C. | Aluminium |
| D. | Bronze |
| Answer» C. Aluminium | |
| 66. |
A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses 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 | |
| 67. |
Low voltage at motor terminals is due to%! |
| A. | Inadequate motor wiring |
| B. | Poorly regulated power supply |
| C. | Any one of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 68. |
In an induction motor if air-gap is increased%! |
| A. | The power factor will be low |
| B. | Windage losses will be more |
| C. | Bearing friction will reduce |
| D. | Copper loss will reduce in an induction motor |
| Answer» B. Windage losses will be more | |
| 69. |
What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero?%! |
| A. | The slip of the motor will be 5% |
| B. | The rotor will not run |
| C. | The rotor will run at very high speed |
| D. | The torque produced will be very large |
| Answer» C. The rotor will run at very high speed | |
| 70. |
When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered%! |
| A. | In series |
| B. | In parallel |
| C. | In series-parallel |
| D. | In parallel with stator |
| Answer» C. In series-parallel | |
| 71. |
In squirrel cage induction motors, the rotor slots are usually given slight skew in order to%! |
| A. | Reduce windage losses |
| B. | Reduce eddy currents |
| C. | Reduce accumulation of dirt and dust |
| D. | Reduce magnetic hum |
| Answer» E. | |
| 72. |
In an induction motor, no-load the slip is generally%! |
| A. | Less than 1 % |
| B. | 1.5 % |
| C. | 2 % |
| D. | 4 % |
| Answer» B. 1.5 % | |
| 73. |
The number of slip rings on a squirrel cage induction motor is usually%! |
| A. | Two |
| B. | Three |
| C. | Four |
| D. | None |
| Answer» E. | |
| 74. |
*$_The frame of an induction motor is usually made of? |
| A. | Silicon steel |
| B. | Cast iron |
| C. | Aluminium |
| D. | Bronze |
| Answer» C. Aluminium | |
| 75. |
*/*_The stating torque of the slip ring induction motor can be increased by adding? |
| A. | External inductance to the rotor |
| B. | External resistance to the rotor |
| C. | External capacitance to the rotor |
| D. | Both resistance and inductance to rotor |
| Answer» C. External capacitance to the rotor | |
| 76. |
*/*_An induction motor is identical to? |
| A. | D.C. compound motor |
| B. | D.C. series motor |
| C. | Synchronous motor |
| D. | Asynchronous motor |
| Answer» E. | |
| 77. |
*/*_Insertion of resistance in the rotor of an induction motor to develop a given torque? |
| A. | Decreases the rotor current |
| B. | Increases the rotor current |
| C. | Rotor current becomes zero |
| D. | Rotor current remains same |
| Answer» E. | |
| 78. |
*/*_The torque developed by a 3-phase induction motor least depends on? |
| A. | Rotor current |
| B. | Rotor power factor |
| C. | Rotor e.m.f. |
| D. | Shaft diameter |
| Answer» E. | |
| 79. |
*/*_The speed of a squirrel-cage induction motor can be controlled by all of the following except? |
| A. | Changing supply frequency |
| B. | Changing number of poles |
| C. | Changing winding resistance |
| D. | Reducing supply voltage |
| Answer» D. Reducing supply voltage | |
| 80. |
*/*_Low voltage at motor terminals is due to? |
| A. | Inadequate motor wiring |
| B. | Poorly regulated power supply |
| C. | Any one of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 81. |
*/*_The 'cogging' of an induction motor can be avoided by? |
| A. | Proper ventilation |
| B. | Using DOL starter |
| C. | Autotransformer starter |
| D. | Having number of rotor slots more or less than the number of stator slots (not equal) |
| Answer» E. | |
| 82. |
*/*_For driving high inertia loads best type of induction motor suggested is? |
| A. | Slip ring type |
| B. | Squirrel-cage type |
| C. | Any of the above |
| D. | None of the above |
| Answer» B. Squirrel-cage type | |
| 83. |
*/*_An induction motor is? |
| A. | Self-starting with zero torque |
| B. | Self-starting with high torque |
| C. | Self-starting with low torque |
| D. | Non-self starting |
| Answer» D. Non-self starting | |
| 84. |
*/*_For which motor the speed can be controlled from rotor side?? |
| A. | Squirrel-cage induction motor |
| B. | Slip-ring induction motor |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» C. Both (A) and (B) | |
| 85. |
*/*_A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses 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 | |
| 86. |
*/*_In squirrel cage induction motors, the rotor slots are usually given slight skew in order to? |
| A. | Reduce windage losses |
| B. | Reduce eddy currents |
| C. | Reduce accumulation of dirt and dust |
| D. | Reduce magnetic hum |
| Answer» E. | |
| 87. |
*/*_When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered? |
| A. | In series |
| B. | In parallel |
| C. | In series-parallel |
| D. | In parallel with stator |
| Answer» C. In series-parallel | |
| 88. |
*/*_What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero?? |
| A. | The slip of the motor will be 5% |
| B. | The rotor will not run |
| C. | The rotor will run at very high speed |
| D. | The torque produced will be very large |
| Answer» C. The rotor will run at very high speed | |
| 89. |
*/*_In an induction motor if air-gap is increased? |
| A. | The power factor will be low |
| B. | Windage losses will be more |
| C. | Bearing friction will reduce |
| D. | Copper loss will reduce in an induction motor |
| Answer» B. Windage losses will be more | |
| 90. |
*/*_The number of slip rings on a squirrel cage induction motor is usually? |
| A. | Two |
| B. | Three |
| C. | Four |
| D. | None |
| Answer» E. | |
| 91. |
*/*_In an induction motor, no-load the slip is generally? |
| A. | Less than 1 % |
| B. | 1.5 % |
| C. | 2 % |
| D. | 4 % |
| Answer» B. 1.5 % | |
| 92. |
*/*_Rotor rheostat control method of speed control is used for? |
| A. | Squirrel-cage induction motors only |
| B. | Slip ring induction motors only |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» C. Both (A) and (B) | |
| 93. |
*/*_As load on an induction motor goes on increasing? |
| A. | Its power factor goes on decreasing |
| B. | Its power factor remains constant |
| C. | Its power factor goes on increasing even after full load |
| D. | Its power factor goes on increasing up to full load and then it falls again |
| Answer» E. | |
| 94. |
%_As load on an induction motor goes on increasing_% |
| A. | Its power factor goes on decreasing |
| B. | Its power factor remains constant |
| C. | Its power factor goes on increasing even after full load |
| D. | Its power factor goes on increasing up to full load and then it falls again |
| Answer» E. | |
| 95. |
_ Rotor rheostat control method of speed control is used for$? |
| A. | Squirrel-cage induction motors only |
| B. | Slip ring induction motors only |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» C. Both (A) and (B) | |
| 96. |
_ The vafcie of transformation ratio of an induction motor can be found by$? |
| A. | Open-circuit test only |
| B. | Short-circuit test only |
| C. | Stator resistance test |
| D. | None of the above |
| Answer» C. Stator resistance test | |
| 97. |
_ Which of the following component is usually fabricated out of silicon steel?$? |
| A. | Bearings |
| B. | Shaft |
| C. | Stator core |
| D. | None of the above |
| Answer» D. None of the above | |
| 98. |
_ Slip of an induction motor is negative when$? |
| A. | Magnetic field and rotor rotate in opposite direction |
| B. | Rotor speed is less than the synchronous speed of the field and are in the same direction |
| C. | Rotor speed is more than the synchronous speed of the field and are in the same direction |
| D. | None of the above |
| Answer» D. None of the above | |
| 99. |
_ Reduced voltage starter can be used with$? |
| A. | Slip ring motor only but not with squirrel cage induction motor |
| B. | Squirrel cage induction motor only but not with slip ring motor |
| C. | Squirrel cage as well as slip ring induction motor |
| D. | None of the above |
| Answer» D. None of the above | |
| 100. |
_ A 3-phase slip ring motor has$? |
| A. | Double cage rotor |
| B. | Wound rotor |
| C. | Short-circuited rotor |
| D. | Any of the above |
| Answer» C. Short-circuited rotor | |