MCQOPTIONS
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MCQOPTIONS
This section includes 20 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. |
The efficiency of a transformer can be calculated accurately from ___________ |
| A. | Open circuit test, Short circuit test |
| B. | Open circuit test, Short circuit test, Sumpner’s test |
| C. | Sumpner’s test |
| D. | load test |
| Answer» B. Open circuit test, Short circuit test, Sumpner’s test | |
| 2. |
From the above graph of the core losses per cycle is, the eddy losses per phase for a transformer at a operating frequency of 40 Hz is? |
| A. | 15 W |
| B. | 20W |
| C. | 35W |
| D. | 32W |
| Answer» B. 20W | |
| 3. |
From the above graph of the core losses per cycle is, the hysteresis losses per phase for a transformer at a operating frequency of 40 Hz is? |
| A. | 20W |
| B. | 30W |
| C. | 80W |
| D. | 32W |
| Answer» B. 30W | |
| 4. |
The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is zero at __________ |
| A. | 0.45 lagging |
| B. | 0.45 leading |
| C. | 0.9 lagging |
| D. | 0.9 leading |
| Answer» D. 0.9 leading | |
| 5. |
The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is maximum at __________ |
| A. | 0.45 lagging |
| B. | 0.45 leading |
| C. | 0.9 lagging |
| D. | 0.9 leading |
| Answer» B. 0.45 leading | |
| 6. |
The load current at which maximum efficiency occurs is independent of the load power factor. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7. |
The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The given total losses at full load is 200 W. The pu resistance is? |
| A. | 0.01 |
| B. | 0.1 |
| C. | 1.0 |
| D. | 0.0196 |
| Answer» B. 0.1 | |
| 8. |
The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The total losses at this condition is? |
| A. | 408W |
| B. | 4.08kW |
| C. | 204W |
| D. | 2.04kW |
| Answer» B. 4.08kW | |
| 9. |
It is possible to attain maximum efficiency in a transformer when the ______ |
| A. | core losses are equal to rated full load copper losses |
| B. | core losses are more than rated full load copper losses |
| C. | core losses and full load copper losses are constant |
| D. | copper loss also becomes constant |
| Answer» B. core losses are more than rated full load copper losses | |
| 10. |
Which of the following mentioned losses occur in a transformer? |
| A. | Hysteresis losses; Eddy current losses; Dielectric losses; Stray load losses |
| B. | Hysteresis losses; Eddy current losses; |
| C. | Dielectric losses; Stray load losses |
| D. | Hysteresis losses; Eddy current losses; Stray load losses |
| Answer» B. Hysteresis losses; Eddy current losses; | |
| 11. |
Which of the statements made here are incorrect regarding the transformer? |
| A. | I,III |
| B. | II,IV |
| C. | 1,III |
| D. | I,IV,IIIView Answer |
| Answer» B. II,IV | |
| 12. |
Which of the statements made here are correct regarding the transformer? |
| A. | I, III |
| B. | II, IV |
| C. | 1, III |
| D. | I, IV, IIIView Answer |
| Answer» C. 1, III | |
| 13. |
THE_EFFICIENCY_OF_A_20_KVA,_2000/200_V,_SINGLE_PHASE_TRANSFORMER_AT_UNITY_PF_IS_98%._THE_GIVEN_TOTAL_LOSSES_AT_FULL_LOAD_IS_200_W._THE_PU_RESISTANCE_IS?$ |
| A. | 0.01 |
| B. | 0.1 |
| C. | 1.0 |
| D. | 0.0196 |
| Answer» B. 0.1 | |
| 14. |
The load current at which maximum efficiency occurs is independent of the load power factor.$ |
| A. | True |
| B. | False |
| Answer» C. | |
| 15. |
The efficiency of a transformer can be calculated accurately from |
| A. | Open circuit test, Short circuit test |
| B. | Open circuit test, Short circuit test, Sumpner’s test |
| C. | Sumpner’s test |
| D. | load test |
| Answer» B. Open circuit test, Short circuit test, Sumpner‚Äö√Ñ√∂‚àö√ë‚àö¬•s test | |
| 16. |
The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is zero at |
| A. | 0.45 lagging |
| B. | 0.45 leading |
| C. | 0.9 lagging |
| D. | 0.9 leading |
| Answer» D. 0.9 leading | |
| 17. |
The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The the total losses at this condition i? |
| A. | 408W |
| B. | 4.08kW |
| C. | 204W |
| D. | 2.04kW |
| Answer» B. 4.08kW | |
| 18. |
It is possible to attain maximum efficiency in a transformer when the |
| A. | core losses are equal to rated full load copper losses |
| B. | core losses are more than rated full load copper losses |
| C. | core losses and full load copper losses are constant |
| D. | copper loss also becomes constant |
| Answer» B. core losses are more than rated full load copper losses | |
| 19. |
Mutual flux ______ at the lagging loading and it _____ at the leading power factor. |
| A. | decreases, increases |
| B. | increases,increases |
| C. | decreases, decreases |
| D. | increases, decreases |
| Answer» B. increases,increases | |
| 20. |
Which of the below mentioned losses occur in a transformer? |
| A. | Hysteresis losses ;Eddy current losses; Dielectric losses; Stray load losses |
| B. | Hysteresis losses ;Eddy current losses; |
| C. | Dielectric losses; Stray load losses |
| D. | Hysteresis losses ;Eddy current losses; Stray load losses |
| Answer» B. Hysteresis losses ;Eddy current losses; | |