MCQOPTIONS
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MCQOPTIONS
This section includes 120 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Slip ring motor is recommended where |
| A. | Speed control is required |
| B. | Frequent starting, stopping and reversing is required |
| C. | High starting torque is needed |
| D. | All above features are required |
| Answer» E. | |
| 102. |
A squirrel cage induction motor is not selected when |
| A. | Initial cost is the main consideration |
| B. | Maintenance cost is to be kept low |
| C. | Higher starting torque is the main consideration |
| D. | All above considerations are involved |
| Answer» D. All above considerations are involved | |
| 103. |
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 | |
| 104. |
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) | |
| 105. |
The starting torque of a three phase induction motor can be increased by |
| A. | Increasing slip |
| B. | Increasing current |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» D. None of the above | |
| 106. |
Slip rings are usually made of |
| A. | Copper |
| B. | Carbon |
| C. | Phosphor bronze |
| D. | Aluminium |
| Answer» D. Aluminium | |
| 107. |
Which is of the following data is required to draw the circle diagram for an induction motor? |
| A. | Block rotor test only |
| B. | No load test only |
| C. | Block rotor test and no-load test |
| D. | Block rotor test, no-load test and stator resistance test |
| Answer» E. | |
| 108. |
A_3-PHASE,_4-POLE,_50_HZ_INDUCTION_MOTOR_IS_USES_DOL_METHOD_OF_STARTING._IT_IS_LATER_REPLACED_BY_REACTANCE_METHOD_OF_STARTING_WITH_A_FRACTION_OF_‚ÄÖ√Ñ√∂‚ÀÖ√Ë‚Àւ§X‚ÄÖ√Ñ√∂‚ÀÖ√Ë‚ÀÖ¬•,_THEN_THE?$# |
| A. | |
| B. | x |
| C. | x^2 |
| Answer» B. x | |
| 109. |
Series reactor method of starting has main disadvantage of$ |
| A. | lowering the starting power |
| B. | increasing the starting current |
| C. | increasing starting torque |
| D. | all of the mentioned |
| Answer» B. increasing the starting current | |
| 110. |
A 3-phase, 4-pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by reactance method of starting with a fraction of ‘x’, then the$# |
| A. | |
| B. | x |
| C. | x^2 |
| Answer» C. x^2 | |
| 111. |
Auto transformer method of starting has most acceptable method for the starting of the induction motor due to |
| A. | maximum torque |
| B. | maximum reduction of inrush current |
| C. | variable tapping |
| D. | all of he mentioned |
| Answer» B. maximum reduction of inrush current | |
| 112. |
For the application requiring high starting torque and minimum starting current, the most suitable starting method will be |
| A. | Auto transformer starting method |
| B. | Reactance starting method |
| C. | DOL method |
| D. | Star-Delta method |
| Answer» B. Reactance starting method | |
| 113. |
A 3-phase, 4-pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by auto transformer method of starting with a tapping ratio of ‘x’, then the$ |
| A. | |
| B. | x |
| C. | x^2 |
| Answer» C. x^2 | |
| 114. |
Series reactor method of starting has main disadvantage of lowering the starting power. This can be overcome by |
| A. | using series resistance |
| B. | using parallel reactor |
| C. | using parallel resistance |
| D. | using series reactor |
| Answer» B. using parallel reactor | |
| 115. |
External methods of induction motor starting is employed t? |
| A. | Reduce the voltage |
| B. | Reduce the current |
| C. | improve efficiency |
| D. | all of the mentioned |
| Answer» B. Reduce the current | |
| 116. |
The method which employs reduction of the voltage while induction motor starting is/are |
| A. | |
| B. | |
| Answer» B. | |
| 117. |
For a 4-pole, 50 Hz induction motor has starting current as 5 times to that of the full load current working at a speed of 1450rpm. |
| A. | |
| B. | 0.83 |
| C. | 0.17 |
| Answer» B. 0.83 | |
| 118. |
Full voltage starting of induction motor may cause |
| A. | dip in the voltages |
| B. | high inrush current |
| C. | high losses |
| D. | all of the mentioned |
| Answer» B. high inrush current | |
| 119. |
Starters are required in the induction motor because |
| A. | of high starting current |
| B. | they are not self starting |
| C. | torque produced is very low at starting to overcome inertia |
| D. | all of the mentioned |
| Answer» B. they are not self starting | |
| 120. |
Voltage induce in the induction motor is highest at |
| A. | starting |
| B. | standstill |
| C. | rated speed |
| D. | any of the mentioned |
| Answer» B. standstill | |