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.
| 151. |
The good power factor of an induction motor can be achieved if the average flux density in the air gap is |
| A. | Absent |
| B. | Small |
| C. | Large |
| D. | Infinity |
| Answer» C. Large | |
| 152. |
The low power factor of induction motor is due to |
| A. | Rotor leakage reactance |
| B. | Stator reactance |
| C. | The reactive lagging magnetizing current necessary to generate the magnetic flux |
| D. | All of the above |
| Answer» E. | |
| 153. |
A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be |
| A. | 200 Hz |
| B. | 50 Hz |
| C. | 2 Hz |
| D. | 0.2 Hz |
| Answer» D. 0.2 Hz | |
| 154. |
A 3-phase induction motor delta connected is carrying too heavy 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 phase |
| C. | Will stop and carry heavy current causing permanent damage to its winding |
| D. | Will continue running without any harm to the winding |
| Answer» D. Will continue running without any harm to the winding | |
| 155. |
An induction motor can run at synchronous speed when |
| A. | It is run on load |
| B. | It is run in reverse direction |
| C. | It is run on voltage higher than the rated voltage |
| D. | e.m.f. is injected in the rotor circuit |
| Answer» E. | |
| 156. |
The torque of an induction motor is |
| A. | Directly proportional to slip |
| B. | Inversely proportional to slip |
| C. | Proportional to the square of the slip |
| D. | None of the above |
| Answer» B. Inversely proportional to slip | |
| 157. |
5 H.P., 50Hz, 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. | |
| 158. |
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 | |
| 159. |
A double squirrel-cage induction motor has |
| A. | Two rotors moving in opposite direction |
| B. | Two parallel windings in stator |
| C. | Two parallel windings in rotor |
| D. | Two series windings in stator |
| Answer» D. Two series windings in stator | |
| 160. |
Insertion of resistance in the stator of an induction motor |
| A. | Increases the load torque |
| B. | Decreases the starting torque |
| C. | Increases the starting torque |
| D. | None of the above |
| Answer» C. Increases the starting torque | |
| 161. |
In three-phase induction motors sometimes copper bars are placed deep in the rotor to |
| A. | Improve starting torque |
| B. | Reduce copper losses |
| C. | Improve efficiency |
| D. | Improve power factor |
| Answer» B. Reduce copper losses | |
| 162. |
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. | |
| 163. |
A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full 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. | |
| 164. |
The purpose of using short-circuit gear is |
| A. | To short circuit the rotor at slip rings |
| B. | To short circuit the starting resistances in the starter |
| C. | To short circuit the stator phase of motor to form star |
| D. | None of the above |
| Answer» B. To short circuit the starting resistances in the starter | |
| 165. |
In a three-phase induction motor |
| A. | Power factor at starting is high as compared to that while running |
| B. | Power factor at starting is low as compared to that while running |
| C. | Power factor at starting in the same as that while running |
| D. | None of these |
| Answer» C. Power factor at starting in the same as that while running | |