MCQOPTIONS
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MCQOPTIONS
This section includes 244 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
The travelling speed of cranes varies from from |
| A. | 20 to 30 m/s |
| B. | 10 to 15 m/s |
| C. | 5 to 10 m/s |
| D. | 1 to 2.5 m/s |
| Answer» E. | |
| 152. |
Among the following which one exhibits linearly rising load torque characteristics? |
| A. | Elevators |
| B. | Rolling Mills |
| C. | Fan load |
| D. | Separately excited dc generator connected to the resistive load |
| Answer» E. | |
| 153. |
........ has relatively wider range of speed control |
| A. | Synchronous motor |
| B. | Slip ring induction motor |
| C. | Squirrel case induction motor |
| D. | DC shunt motor |
| Answer» E. | |
| 154. |
Servo motors are an example of which type of load? |
| A. | Pulsating loads |
| B. | Short time loads |
| C. | Impact loads |
| D. | Short time intermittent loads |
| Answer» C. Impact loads | |
| 155. |
In squirrel cage induction motors which of the following methods of startingcannot be used ? |
| A. | Resistance in rotor circuit |
| B. | Resistance in stator circuit |
| C. | Auto transformer starting |
| D. | Start Delta starting |
| Answer» B. Resistance in stator circuit | |
| 156. |
Reverse motoring mode is available in fourth quadrant. |
| A. | True |
| B. | False |
| C. | none |
| D. | all |
| Answer» B. False | |
| 157. |
Locomotive having monomotor bogies |
| A. | has better coefficient of adhesion |
| B. | are suited both for passanger as well as freight service |
| C. | has better riding qualities due to the reduction of lateral forces |
| D. | has all above qualities |
| Answer» E. | |
| 158. |
Regenerative braking mode can be achieved in which quadrant (V-I curve)? |
| A. | Third |
| B. | Second |
| C. | Fourth |
| D. | First |
| Answer» C. Fourth | |
| 159. |
When the load is above a synchronous motor is found to be more economical. |
| A. | 2 kW |
| B. | 20 kW |
| C. | 50 kW |
| D. | 100 kW |
| Answer» E. | |
| 160. |
_______ frequency is not common in low frequency traction system |
| A. | 40 Hz |
| B. | 25 Hz |
| C. | 16 Hz |
| D. | all |
| Answer» B. 25 Hz | |
| 161. |
There are three types of the solar cells. |
| A. | True |
| B. | False |
| C. | none |
| D. | all |
| Answer» B. False | |
| 162. |
Belt conveyors offer |
| A. | zero starting torque |
| B. | low starting torque |
| C. | medium starting torque |
| D. | high starting torque. |
| Answer» E. | |
| 163. |
The range of horse power of electric motor drives for rolling mills is of the order of |
| A. | 1 to 10 HP |
| B. | 15 to 25 HP |
| C. | 50 to 100 HP |
| D. | 100 to 500 HP. |
| Answer» E. | |
| 164. |
The turn-o times of the devices in the increasing order is ___________I. MOSFET II. BJT III. IGBT IV. Thyristor |
| A. | I, III, II, IV |
| B. | I, II, III, IV |
| C. | III, I, II, IV |
| D. | III, II, IV, I |
| Answer» B. I, II, III, IV | |
| 165. |
_______ locomotive has the highest operational availability. |
| A. | Electric |
| B. | Diesel |
| C. | Steam |
| D. | none |
| Answer» B. Diesel | |
| 166. |
Due to which of the following co-efficient of adhesion improves ? |
| A. | Rust on the rails |
| B. | Dust on the rails |
| C. | Sand on the rails |
| D. | All of the above |
| Answer» E. | |
| 167. |
In motor circuit static frequency changers are used for |
| A. | power factor improvement |
| B. | improved cooling |
| C. | reversal of direction |
| D. | speed regulation. |
| Answer» E. | |
| 168. |
1/2 hour rated motors are used for |
| A. | light duty cranes |
| B. | medium duty cranes |
| C. | heavy duty cranes |
| D. | none of the above. |
| Answer» C. heavy duty cranes | |
| 169. |
Which of the following types of motor enclosure is safest ? |
| A. | Totally enclosed |
| B. | Totally enclosed fan cooled |
| C. | Open type |
| D. | Semi closed |
| Answer» C. Open type | |
| 170. |
R.M.S value of the sinusoidal waveform V=V sin(ωt+α). |
| A. | V ÷2 |
| B. | V ÷2 |
| C. | V ÷2 |
| D. | V ÷3 |
| Answer» B. V ÷2 | |
| 171. |
The number of operations per hour in case of class IV contactor will be around |
| A. | 100 |
| B. | 600 |
| C. | 900 |
| D. | 1200. |
| Answer» E. | |
| 172. |
In India, electrification of railway track was done for the first time in which of thefollowing years ? |
| A. | 1820—1825 |
| B. | 1880—1885 |
| C. | 1925—1932 |
| D. | 1947—1954 |
| Answer» D. 1947—1954 | |
| 173. |
Overhead lines for power supply to tramcars are at a minimum height of |
| A. | 3 m |
| B. | 6 m |
| C. | 10 m |
| D. | tO m |
| Answer» D. tO m | |
| 174. |
For medium duty cranes the short time rating motor used is |
| A. | 10 minutes |
| B. | 15 minutes |
| C. | 30 minutes |
| D. | any of the above |
| Answer» D. any of the above | |
| 175. |
To get speed higher than the base speed of the dc shunt motor |
| A. | armature resistance control is used |
| B. | field resistance control is used |
| C. | armature voltage control is used |
| D. | none of these. |
| Answer» C. armature voltage control is used | |
| 176. |
Light duty cranes are used in which of the following ? |
| A. | Power houses |
| B. | Pumping stations |
| C. | Automobile workshops |
| D. | All of the above |
| Answer» E. | |
| 177. |
In case of traveling cranes, the motor preferred for boom hoist is |
| A. | AC slip ring motor |
| B. | Ward Leonard controlled DC shunt motor |
| C. | Synchronous motor |
| D. | Single phase motor. |
| Answer» B. Ward Leonard controlled DC shunt motor | |
| 178. |
For high frequency choppers the device that is preferred is |
| A. | Thyristor |
| B. | TRIAC |
| C. | Transistor |
| D. | GTO. |
| Answer» D. GTO. | |
| 179. |
Which off the following motors is used for elevators? |
| A. | Induction motor |
| B. | Synchronous motor |
| C. | Capacitor start single phase motor |
| D. | Any of the above |
| Answer» B. Synchronous motor | |
| 180. |
Which of the following motor is preferred for blowers ? |
| A. | wound rotor induction motor |
| B. | squirrel cage induction motor |
| C. | dc shunt motor |
| D. | dc series motor. |
| Answer» C. dc shunt motor | |
| 181. |
Rolling mills exhibit what type of load torque characteristics? |
| A. | Constant torque characteristics |
| B. | Linearly rising torque characteristics |
| C. | Non-Linearly rising torque characteristics |
| D. | Non-Linearly decreasing torque characteristics |
| Answer» E. | |
| 182. |
Which of the relationship is correct in Permanent magnet DC motor? |
| A. | E ∝ (N) |
| B. | E ∝ (N) |
| C. | E ∝ N |
| D. | E2 ∝ N |
| Answer» D. E2 ∝ N | |
| 183. |
The .......motors, because of their inherent characteristics, are best suited for the rolling mills |
| A. | dc motors |
| B. | slip ring induction motors |
| C. | squirrel cage induction motors |
| D. | single phase motors. |
| Answer» B. slip ring induction motors | |
| 184. |
Which of the following alternatives will be cheaper ? |
| A. | A 100 H.P. AC. three phase motor |
| B. | Four motors of 25 H.P. each |
| C. | Five motors of 20 H.P. each |
| D. | Ten motors of 10 H.P. each |
| Answer» B. Four motors of 25 H.P. each | |
| 185. |
While selecting an electric motor for a floor Mill, which electrical characteristicswill be of least significance ? |
| A. | Running characteristics |
| B. | Starting characteristics |
| C. | Efficiency |
| D. | Breaking |
| Answer» E. | |
| 186. |
Ward-Leonard controlled D.C. drives are generally used for excavators. |
| A. | Light duty |
| B. | Medium duty |
| C. | Heavy duty |
| D. | All of the above |
| Answer» D. All of the above | |
| 187. |
In the speed can be varied by changing the position of brushes. |
| A. | slip ring motor |
| B. | schrage motor |
| C. | induction motor |
| D. | repulsion motor |
| Answer» C. induction motor | |
| 188. |
In jaw crushers a motor has to often start against....... load |
| A. | Heavy |
| B. | Medium |
| C. | Normal |
| D. | Low |
| Answer» B. Medium | |
| 189. |
Motors preferred for rolling mill drive is |
| A. | dc motors |
| B. | ac slip ring motors with speed control |
| C. | any of the above |
| D. | none of the above. |
| Answer» D. none of the above. | |
| 190. |
SCR is uni-directional in nature. |
| A. | True |
| B. | False |
| C. | none |
| D. | all |
| Answer» B. False | |
| 191. |
Which ofthefollowingmotors is preferred for traction work ? |
| A. | Universal motor |
| B. | D.C. series motor |
| C. | Synchronous motor |
| D. | Three-phase induction motor |
| Answer» C. Synchronous motor | |
| 192. |
A DC chopper feeds an RLE load. If the value of E is increased by 20%, the current ripple ________ |
| A. | increases by 20% |
| B. | decreases by 20% |
| C. | increases only 20% |
| D. | remains the same |
| Answer» E. | |
| 193. |
Which of the following machines has heavy fluctuating of load ? |
| A. | Printing machine |
| B. | Punching machine |
| C. | Planer |
| D. | Lathe |
| Answer» C. Planer | |
| 194. |
Which part of a motor needs maximum attention for maintenance ? |
| A. | Frame |
| B. | Rearing |
| C. | Stator winding |
| D. | Rotor winding |
| Answer» C. Stator winding | |
| 195. |
The range of ratings of electric motor used for rolling mills is of the order of |
| A. | 10 to 25 kW |
| B. | 25 to 85 kW |
| C. | 85 to 400 kW |
| D. | 400 to 1000 kW |
| Answer» D. 400 to 1000 kW | |
| 196. |
In jaw crushers a motor has to often start against load. |
| A. | heavy |
| B. | medium |
| C. | normal |
| D. | low |
| Answer» B. medium | |
| 197. |
Which of the following braking systems on the locomotives is costly ? |
| A. | Regenerative braking on electric locomotives |
| B. | Vacuum braking on diesel locomo-tives |
| C. | Vacuum braking on steam locomo-tives |
| D. | All braking systems are equally costly |
| Answer» B. Vacuum braking on diesel locomo-tives | |
| 198. |
For three-phase induction motors which of the following is the least efficient method of speed control ? |
| A. | Cascade control |
| B. | Pole changing |
| C. | Rheostatic control |
| D. | Combination of cascade and pole changing |
| Answer» D. Combination of cascade and pole changing | |
| 199. |
A pony motor is used for the starting which of the following motors ? |
| A. | Squirrel cage induction motor |
| B. | Schrage motor |
| C. | Synchronous motor |
| D. | None of the above |
| Answer» D. None of the above | |
| 200. |
The motor in close are used for collieries, chemical plant is |
| A. | Flame proof type |
| B. | Splash proof type |
| C. | Totally enclosed type |
| D. | Pipe ventilated type |
| Answer» B. Splash proof type | |