MCQOPTIONS
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MCQOPTIONS
This section includes 9 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 for primary and 3+ j11 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 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 | |