MCQOPTIONS
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MCQOPTIONS
This section includes 25 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. |
Two tranformer having same voltage but different KVA are operating in parallel. For a good load sharing __________ |
| A. | impedance must be equal |
| B. | pu impedances must be equal |
| C. | pu impedance and X/R ratios must be equal |
| D. | impedance and X/R ratios must be equal |
| Answer» D. impedance and X/R ratios must be equal | |
| 2. |
In a transformer, we place the tapping windings at the middle because __________ |
| A. | of radial forces on the windings |
| B. | axial forces on the windings |
| C. | insulation level of the winding |
| D. | to provide a mechanical balance to the windings |
| Answer» C. insulation level of the winding | |
| 3. |
The tappings on the transformers is provided on __________ |
| A. | h.v side at one end of the winding |
| B. | l.v. side at one end of the winding |
| C. | h.v side at middle |
| D. | l.v side at middle |
| Answer» D. l.v side at middle | |
| 4. |
If a transformer is at no load, then it will act like __________ |
| A. | a resistor at p.f = 0 |
| B. | an inductive reactor at 0.2 lagging |
| C. | a capacitive reactor at0.2 leading |
| D. | an inductive reactor at 0.8 lagging |
| Answer» C. a capacitive reactor at0.2 leading | |
| 5. |
A 1-phase tranformer has a leakage impedance of 1+ j4 Ω for primary and 3+ j11 Ω for secondary windings. This transformer has __________ |
| A. | H.V primary |
| B. | Medium voltage primary |
| C. | L.V primary |
| D. | L.V secondary |
| Answer» D. L.V secondary | |
| 6. |
Maximum efficiency of a transformer for a constant load current, occurs at __________ |
| A. | at any p.f |
| B. | zero p.f leading |
| C. | zero p.f lagging |
| D. | unity p.f |
| Answer» E. | |
| 7. |
Three transformers having identical dimensions but with core of iron, aluminium and wood are wound with same number of turns and have same supply. Then choose the order for eddy current losses. |
| A. | wood > aluminium > iron |
| B. | aluminium > iron > wood |
| C. | iron > wood > aluminium |
| D. | iron > aluminium > wood |
| Answer» B. aluminium > iron > wood | |
| 8. |
Three transformers having identical dimensions but with core of iron, aluminium and wood are wound with same number of turns and have same supply. Then choose the order for hysteresis losses. |
| A. | wood > aluminium > iron |
| B. | aluminium > iron > wood |
| C. | iron > wood > aluminium |
| D. | iron > aluminium > wood |
| Answer» E. | |
| 9. |
The voltage regulation of a transformer depends on its __________ |
| A. | A, B, C, E |
| B. | A, B, C, D, E |
| C. | A, B, D, E |
| D. | A, B, C, DView Answer |
| Answer» B. A, B, C, D, E | |
| 10. |
The voltage regulation of a transformer at full-load 0.8 p.f leading is -2%. Its voltage regulation at full load 0.8 p.f lagging _____________ |
| A. | will be positive |
| B. | will be negative |
| C. | may be positive |
| D. | may be negative |
| Answer» B. will be negative | |
| 11. |
Which of the above are correct for an auto transformer when compared to the identical rating two winding transformer? |
| A. | I, II |
| B. | II, III |
| C. | 1, III |
| D. | I, II, III, IVView Answer |
| Answer» B. II, III | |
| 12. |
The statements which support the points that auto transformers are disadvantageous as compared to 2-winding transformer? |
| A. | I, III |
| B. | II, III |
| C. | II, IV |
| D. | I, II, IVView Answer |
| Answer» D. I, II, IVView Answer | |
| 13. |
The statements which support the points that auto transformers are advantageous? |
| A. | I, II, III |
| B. | II, III, IV |
| C. | I, II, III, IV |
| D. | I, IVView Answer |
| Answer» B. II, III, IV | |
| 14. |
THREE_TRANSFORMERS_HAVING_IDENTICAL_DIMENSIONS_BUT_WITH_CORE_OF_IRON,_ALUMINIUM_AND_WOOD_ARE_WOUND_WITH_SAME_NUMBER_OF_TURNS_AND_HAVE_SAME_SUPPLY.?$ |
| A. | |
| B. | wood > aluminium > iron |
| C. | aluminium > iron > wood |
| Answer» B. wood > aluminium > iron | |
| 15. |
A 1-phase tranformer has a leakage impedance of 1+ j4 Ω for primary and 3+ j11 Ω for secondary windings. This transformer has$# |
| A. | H.V primary |
| B. | Medium voltage primary |
| C. | L.V primary |
| D. | L.V secondary |
| Answer» D. L.V secondary | |
| 16. |
Maximum_efficiency_of_a_transformer_for_a_constant_load_current_,_occurs_at$ |
| A. | at any p.f |
| B. | zero p.f leading |
| C. | zero p.f lagging |
| D. | unity p.f |
| Answer» E. | |
| 17. |
Two tranformer having same voltage but different KVA are operating in parallel. For a good load sharing, |
| A. | impedance must be equal |
| B. | pu impedances must be equal |
| C. | pu impedance and X/R ratios must be equal |
| D. | impedance and X/R ratios must be equal |
| Answer» D. impedance and X/R ratios must be equal | |
| 18. |
When a transformer winding suffers a short circuit, then inter turns of the same winding experience ______ forces. |
| A. | an attractive |
| B. | a repulsive |
| C. | no force |
| D. | may be attractive or repulsive type |
| Answer» B. a repulsive | |
| 19. |
In a transformer, we place the tapping windings at the middle because |
| A. | of radial forces on the windings |
| B. | axial forces on the windings |
| C. | insulation level of the winding |
| D. | to provide a mechanical balance to the windings |
| Answer» C. insulation level of the winding | |
| 20. |
The tappings on the transformers is provided on |
| A. | h.v side at one end of the winding |
| B. | l.v. side at one end of the winding |
| C. | h.v side at middle |
| D. | l.v side at middle |
| Answer» D. l.v side at middle | |
| 21. |
If a transformer is at no load , then it will act like |
| A. | a resistor at p.f =0 |
| B. | an inductive reactor at 0.2 lagging |
| C. | a capacitive reactor at0.2 leading |
| D. | an inductive reactor at 0.8 lagging |
| Answer» C. a capacitive reactor at0.2 leading | |
| 22. |
The voltage regulation of a transformer depends on its |
| A. | equivalent reactance (B) equivalent resistance |
| B. | load power factor (D)transformer size |
| C. | load current |
| D. | A,B,C,E |
| Answer» B. load power factor (D)transformer size | |
| 23. |
The voltage regulation of a transformer at full-load 0.8 p.f leading is -2%. Its voltage regulation at full load 0.8 p.f lagging |
| A. | will be positive |
| B. | will be negative |
| C. | may be positive |
| D. | may be negative |
| Answer» B. will be negative | |
| 24. |
I. KVA rating : 1/(1-k) |
| A. | |
| B. | |
| C. | |
| Answer» B. | |
| 25. |
While comparing potential transformer to an auto transformer, a potential transformer transfers power ________ |
| A. | conductively |
| B. | inductively |
| C. | both conductively as well as inductively |
| D. | electromagnetic induction |
| Answer» B. inductively | |