MCQOPTIONS
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MCQOPTIONS
This section includes 23 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If the operating voltage of the induction motor is increased by twice while keeping the frequency of the operation constant. Then the new starting torque will be? |
| A. | 4*T |
| B. | 1/4*T |
| C. | T |
| D. | 2*T |
| Answer» B. 1/4*T | |
| 2. |
If the voltage and frequency of the induction machine is reduced to 50% of the operating region,the slip of the machine will be? |
| A. | 2*s |
| B. | s |
| C. | 1/2s |
| D. | 1/s |
| Answer» B. s | |
| 3. |
If the voltage of a three phase induction motor if increased to 200%, then the slip if the machine changes to _________ |
| A. | 1/s |
| B. | s |
| C. | 1/2s |
| D. | 2*s |
| Answer» D. 2*s | |
| 4. |
If the frequency is reduced by 50% for a 3-phase, 50 Hz induction motor having 4 poles. The slip at which the maximum torque occurs becomes _________ |
| A. | 2*s |
| B. | s |
| C. | 1/2s |
| D. | 1/s |
| Answer» B. s | |
| 5. |
I. Maximum torque can be achieved by inserting an additional resistance at desired slip in the rotor. II. Maximum torque can be altered by adding the external resistance in the rotor. |
| A. | Only I is true |
| B. | Both I and II are true |
| C. | Neither I nor II is true |
| D. | Only II is true |
| Answer» B. Both I and II are true | |
| 6. |
A 3-phase induction motor had the maximum rated torque of 40 N-m while the load torque applied to it is 55 N-m. |
| A. | The machine will become unstable |
| B. | The machine will operate in stable region |
| C. | The machine will get heated up |
| D. | The machine will run at dangerously high speed |
| Answer» B. The machine will operate in stable region | |
| 7. |
An induction motor X operating at the slip of 3%. An induction motor Y operating at slip of 40%. |
| A. | Machine X is only stable |
| B. | Machine Y is only stable |
| C. | Both the machine X and Y are stable |
| D. | Neither X nor Y is stable |
| Answer» B. Machine Y is only stable | |
| 8. |
Approximately the efficiency of the rotor of the induction motor depends on the _________ |
| A. | rotor speed |
| B. | synchronous speed |
| C. | rotor speed and synchronous speed |
| D. | magnetic field speed |
| Answer» D. magnetic field speed | |
| 9. |
The rotor of the slip ring induction motor is connected to an ac source and stator is short circuited. If the rotating magnetic field is rotates clockwise, the rotor rotates in _________ |
| A. | anticlockwise |
| B. | clockwise |
| C. | remains stationary |
| D. | any of the mentioned |
| Answer» B. clockwise | |
| 10. |
AN_INDUCTION_MOTOR_X_OPERATING_AT_THE_SLIP_OF_3%.?$ |
| A. | |
| B. | Machine X is only stable |
| C. | Machine Y is only stable |
| Answer» B. Machine X is only stable | |
| 11. |
I. Maximum torque can be achieved by inserting an additional resistance at desired slip in the rotor.$ |
| A. | |
| B. | Only I is true |
| C. | Both I and II are true |
| Answer» B. Only I is true | |
| 12. |
A 3-phase induction motor had the maximum rated torque of 40 N-m while the load torque applied to it is 55 N-m.$ |
| A. | The machine will become unstable |
| B. | The machine will operate in stable region |
| C. | The machine will get heated up |
| D. | The machine will run at dangerously high speed |
| Answer» B. The machine will operate in stable region | |
| 13. |
If the operating voltage of the induction motor is increased by twice while keeping the frequency of the operation constant. |
| A. | |
| B. | 4*T |
| C. | 1/4*T |
| Answer» B. 4*T | |
| 14. |
If the voltage and frequency of the induction machine is reduced to 50% of the operating region,the slip of the machine will be |
| A. | 2*s |
| B. | s |
| C. | 1/2s |
| D. | 1/s |
| Answer» B. s | |
| 15. |
If the voltage of a three phase induction motor if increased to 200%, then the slip if the machine changes to |
| A. | 1/s |
| B. | s |
| C. | 1/2s |
| D. | 2*s |
| Answer» D. 2*s | |
| 16. |
If the frequency is reduced by 50% for a 3-phase, 50 Hz induction motor having 4 poles. The slip at which the maximum torque occurs becomes |
| A. | 2*s |
| B. | s |
| C. | 1/2s |
| D. | 1/s |
| Answer» B. s | |
| 17. |
The power input to the 3-phase induction motor is 60 kW. The stator losses total 1 kW. Find the mechanical power developed at the slip of 3%. |
| A. | 57.23 kW |
| B. | 58 kW |
| C. | 56.8 kW |
| D. | 59 kW |
| Answer» B. 58 kW | |
| 18. |
A 400, 3-phase, 50 Hz, 4 pole induction motor takes a line current of 10 A with 0.86 pf lagging. What is the stator input? |
| A. | 5.95 kW |
| B. | 6.95 kW |
| C. | 4.45 kW |
| D. | 8.38 kW |
| Answer» B. 6.95 kW | |
| 19. |
Approximately the efficiency of the rotor of the induction motor depends on the |
| A. | rotor speed |
| B. | synchronous speed |
| C. | rotor speed and synchronous speed |
| D. | magnetic field speed |
| Answer» D. magnetic field speed | |
| 20. |
On increasing the starting torque of the induction motor, the maximum torque is also increased. |
| A. | False |
| B. | True |
| Answer» B. True | |
| 21. |
If the hysteresis is neglected in the induction machine, then the the air gap flux _______ the resultant mmf. |
| A. | is in phase with |
| B. | lags |
| C. | leads by a small angle |
| D. | can not decide the nature of the operation |
| Answer» B. lags | |
| 22. |
Rotor leakage impedance at starting is different from its value at normal running conditions. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 23. |
The rotor of the slip ring induction motor is connected to an ac source and stator is short circuited. If the rotating magnetic field is rotates clockwise, the rotor rotates in |
| A. | anticlockwise |
| B. | clockwise |
| C. | remains stationary |
| D. | any of the mentioned |
| Answer» B. clockwise | |