McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 301. |
Various methods for starting a three phase induction motor are given, which method will required six stator terminals |
| A. | dol |
| B. | auto transformer |
| C. | start delta |
| D. | rheostat |
| Answer» C. start delta | |
| 302. |
Which of the following parameters of induction motor varies inversely as the supply freq |
| A. | full load speed |
| B. | starting current |
| C. | slip |
| D. | maximum running torque |
| Answer» B. starting current | |
| 303. |
When the supply voltage for an induction motor is reduced by 10%, the maximum running torque will be |
| A. | decrease by 10% |
| B. | decrease by 20% |
| C. | increase by 10% |
| D. | increase by 20% |
| Answer» B. decrease by 20% | |
| 304. |
If the supply freq of an induction motor is increased by 5%, the synchronous speed will |
| A. | decrease by 10% |
| B. | decrease by 5% |
| C. | increase by 5% |
| D. | increase by 10% |
| Answer» C. increase by 5% | |
| 305. |
The direction of rotation of field in a 3-ph induction motor depends upon |
| A. | number of poles |
| B. | magnitude of supply voltage |
| C. | supply freq |
| D. | phase sequence of supply voltage |
| Answer» D. phase sequence of supply voltage | |
| 306. |
The maximum voltage is induced in the rotor of 3-ph induction motor when it---- |
| A. | runs at no load |
| B. | runs at full load |
| C. | is blocked |
| D. | none of the above |
| Answer» A. runs at no load | |
| 307. |
When an induction motor is running at full load, rotor reactance is ------rotor resistance |
| A. | low comparable to |
| B. | very large compared to |
| C. | large compared to |
| D. | none of the above |
| Answer» A. low comparable to | |
| 308. |
If an induction motor is running at slip s ( in decimal) the rotor output is |
| A. | (1+s) x rotor input |
| B. | (s-1) x rotor input |
| C. | s x rotor input |
| D. | (1-s) x rotor input |
| Answer» D. (1-s) x rotor input | |
| 309. |
The conditions of induction motor at no load resembles those of transformer whose secondary is…… |
| A. | short circuited |
| B. | open circuited |
| C. | supplying a variable resistive load |
| D. | none of the above |
| Answer» A. short circuited | |
| 310. |
The input to a 3-ph induction motor is 50KW. The stator losses amount to 800W. The rotor cu loss per phase is (slip = 3%) |
| A. | 576w |
| B. | 492w |
| C. | 1050w |
| D. | 728w |
| Answer» B. 492w | |
| 311. |
The input to a 3-ph induction motor is 50KW. The stator losses amount to 800W. The mechanical power developed (slip = 3%) |
| A. | 59hp |
| B. | 69hp |
| C. | 47hp |
| D. | 64hp |
| Answer» D. 64hp | |
| 312. |
An 8-pole , 50Hz,3-ph indduction motor running with a slip of 4% is taking 20KW. Stator losses amount 0.5KW. The total torque develped is |
| A. | 248nm |
| B. | 312nm |
| C. | 195nm |
| D. | 214nm |
| Answer» A. 248nm | |
| 313. |
A 6pole, 3-ph induction motor is runs at a speed of 960rpm & the shaft torque is 135.7Nm. Calculate the rotor cu loss if the friction and windage losses amount to 150W. The suppy freq is 50Hz. |
| A. | 625w |
| B. | 785w |
| C. | 425w |
| D. | 574w |
| Answer» D. 574w | |
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