MCQOPTIONS
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MCQOPTIONS
This section includes 209 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The transformer ratings are usually expressed in terms of~! |
| A. | volts |
| B. | amperes |
| C. | kW |
| D. | kVA |
| Answer» E. | |
| 2. |
Which of the following is not a routine test on transformers?%! |
| A. | Core insulation voltage test |
| B. | Impedance test |
| C. | Radio interference test |
| D. | Polarity test |
| Answer» D. Polarity test | |
| 3. |
During open circuit test of a transformer%! |
| A. | primary is supplied rated voltage |
| B. | primary is supplied full-load current |
| C. | primary is supplied current at reduced voltage |
| D. | primary is supplied rated kVA |
| Answer» B. primary is supplied full-load current | |
| 4. |
An ideal transformer has infinite values of primary and secondary inductances. The statement is%! |
| A. | true |
| B. | false |
| Answer» C. | |
| 5. |
When the equivalent circuit diagram of doouble squirrelcage induction motor is constructed the two cages can be considered%! |
| A. | in series |
| B. | in parallel |
| C. | in series-parallel |
| D. | in parallel with stator |
| Answer» C. in series-parallel | |
| 6. |
Which of the following is not the standard voltage for power supply in India?%! |
| A. | llkV |
| B. | 33kV |
| C. | 66 kV |
| D. | 122 kV |
| Answer» E. | |
| 7. |
Power transformers are designed to have maximum efficiency at%! |
| A. | nearly full load |
| B. | 70% full load |
| C. | 50% full load |
| D. | no load |
| Answer» B. 70% full load | |
| 8. |
The thickness of laminations used in a transformer is usually%! |
| A. | 0.4 mm to 0.5 mm |
| B. | 4 mm to 5 mm |
| C. | 14 mm to 15 mm |
| D. | 25 mm to 40 mm |
| Answer» B. 4 mm to 5 mm | |
| 9. |
Helical coils can be used on%! |
| A. | low voltage side of high kVA transformers |
| B. | high frequency transformers |
| C. | high voltage side of small capacity transformers |
| D. | high voltage side of high kVA rating transformers |
| Answer» B. high frequency transformers | |
| 10. |
Delta/star transformer works satisfactorily when%! |
| A. | load is balanced only |
| B. | load is unbalanced only |
| C. | on balanced as well as unbalanced loads |
| D. | none of the above |
| Answer» D. none of the above | |
| 11. |
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in%! |
| A. | short-circuiting of the secondaries |
| B. | power factor of one of the transformers is leading while that of the other lagging |
| C. | transformers having higher copper losses will have negligible core losses |
| D. | loading of the transformers not in proportion to their kVA ratings |
| Answer» E. | |
| 12. |
The highest voltage for transmitting electrical power in India is%! |
| A. | 33 kV |
| B. | 66 kV |
| C. | 132 kV |
| D. | 400 kV |
| Answer» E. | |
| 13. |
The chemical used in breather is%! |
| A. | asbestos fiber |
| B. | silica sand |
| C. | sodium chloride |
| D. | silica gel |
| Answer» E. | |
| 14. |
Part of the transformer which is most subject to damage from overheating is%! |
| A. | iron core |
| B. | copper winding |
| C. | winding insulation |
| D. | frame or case |
| Answer» D. frame or case | |
| 15. |
Buchholz's relay gives warning and protection against%! |
| A. | electrical fault inside the transformer itself |
| B. | electrical fault outside the transformer in outgoing feeder |
| C. | for both outside and inside faults |
| D. | none of the above |
| Answer» B. electrical fault outside the transformer in outgoing feeder | |
| 16. |
Which of the following does not change in a transformer?%! |
| A. | Current |
| B. | Voltage |
| C. | Frequency |
| D. | All of the above |
| Answer» D. All of the above | |
| 17. |
The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?%! |
| A. | 2 V |
| B. | 20 V |
| C. | 180 V |
| D. | 18 V |
| Answer» C. 180 V | |
| 18. |
The purpose of providing iron core in a step-up transformer is%! |
| A. | To provide coupling between primary and secondary |
| B. | To increase the magnitude of mutual flux |
| C. | To decrease the magnitude of magnetizing current |
| D. | To provide all above features |
| Answer» D. To provide all above features | |
| 19. |
A Buchholz relay can be installed on%! |
| A. | auto-transformers |
| B. | air-cooled transformers |
| C. | welding transformers |
| D. | oil cooled transformers |
| Answer» E. | |
| 20. |
When secondary of a current transformer is open-circuited its iron core will be%! |
| A. | hot because of heavy iron losses taking place in it due to high flux density |
| B. | hot because primary will carry heavy current |
| C. | cool as there is no secondary current |
| D. | none of above will happen |
| Answer» B. hot because primary will carry heavy current | |
| 21. |
Power transformers are generally designed to have maximum efficiency around%! |
| A. | no-load |
| B. | half-load |
| C. | near full-load |
| D. | 10% overload |
| Answer» D. 10% overload | |
| 22. |
Which winding in a transformer has more number of turns?%! |
| A. | Low voltage winding |
| B. | High voltage winding |
| C. | Primary winding |
| D. | Secondary winding |
| Answer» C. Primary winding | |
| 23. |
The maximum load that a power transformer can carry is limited by its%! |
| A. | temperature rise |
| B. | dielectric strength of oil |
| C. | voltage ratio |
| D. | copper loss |
| Answer» D. copper loss | |
| 24. |
Losses which occur in rotating electric machines and do not occur in trans formers are%! |
| A. | friction and windage losses |
| B. | magnetic losses |
| C. | hysteresis and eddy current losses |
| D. | copper losses |
| Answer» B. magnetic losses | |
| 25. |
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of%! |
| A. | less than 15 A |
| B. | more than 15 A |
| C. | 15 A |
| D. | none of the above |
| Answer» B. more than 15 A | |
| 26. |
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is%! |
| A. | approximately equal to one |
| B. | less than one |
| C. | great than one |
| D. | none of the above |
| Answer» B. less than one | |
| 27. |
Open circuit test on transformers is conducted to determine%! |
| A. | hysteresis losses |
| B. | copper losses |
| C. | core losses |
| D. | eddy current losses |
| Answer» D. eddy current losses | |
| 28. |
Which type of winding is used in 3phase shell-type transformer?%! |
| A. | Circular type |
| B. | Sandwich type |
| C. | Cylindrical type |
| D. | Rectangular type |
| Answer» C. Cylindrical type | |
| 29. |
Natural air cooling is generally restricted for transformers up to%! |
| A. | 1.5 MVA |
| B. | 5 MVA |
| C. | 15 MVA |
| D. | 50 MVA |
| Answer» B. 5 MVA | |
| 30. |
The voltage transformation ratio of a transformer is equal to the ratio of%! |
| A. | primary turns to secondary turns |
| B. | secondary current to primary current |
| C. | secondary induced e.m.f. to primary induced e.m.f. |
| D. | secondary terminal voltage to primary applied voltage |
| Answer» D. secondary terminal voltage to primary applied voltage | |
| 31. |
Which winding of the transformer has less cross-sectional area?%! |
| A. | Primary winding |
| B. | Secondary winding |
| C. | Low voltage winding |
| D. | High voltage winding |
| Answer» E. | |
| 32. |
*$_The purpose of providing iron core in a step-up transformer is? |
| A. | To provide coupling between primary and secondary |
| B. | To increase the magnitude of mutual flux |
| C. | To decrease the magnitude of magnetizing current |
| D. | To provide all above features |
| Answer» D. To provide all above features | |
| 33. |
*$_The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage?? |
| A. | 2 V |
| B. | 20 V |
| C. | 180 V |
| D. | 18 V |
| Answer» C. 180 V | |
| 34. |
*$_Which of the following does not change in a transformer?? |
| A. | Current |
| B. | Voltage |
| C. | Frequency |
| D. | All of the above |
| Answer» D. All of the above | |
| 35. |
*$_Buchholz's relay gives warning and protection against? |
| A. | electrical fault inside the transformer itself |
| B. | electrical fault outside the transformer in outgoing feeder |
| C. | for both outside and inside faults |
| D. | none of the above |
| Answer» B. electrical fault outside the transformer in outgoing feeder | |
| 36. |
*$_Losses which occur in rotating electric machines and do not occur in trans formers are? |
| A. | friction and windage losses |
| B. | magnetic losses |
| C. | hysteresis and eddy current losses |
| D. | copper losses |
| Answer» B. magnetic losses | |
| 37. |
*$_Which type of winding is used in 3phase shell-type transformer?? |
| A. | Circular type |
| B. | Sandwich type |
| C. | Cylindrical type |
| D. | Rectangular type |
| Answer» C. Cylindrical type | |
| 38. |
*$_In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of? |
| A. | less than 15 A |
| B. | more than 15 A |
| C. | 15 A |
| D. | none of the above |
| Answer» B. more than 15 A | |
| 39. |
*$_Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is? |
| A. | approximately equal to one |
| B. | less than one |
| C. | great than one |
| D. | none of the above |
| Answer» B. less than one | |
| 40. |
*$_The voltage transformation ratio of a transformer is equal to the ratio of? |
| A. | primary turns to secondary turns |
| B. | secondary current to primary current |
| C. | secondary induced e.m.f. to primary induced e.m.f. |
| D. | secondary terminal voltage to primary applied voltage |
| Answer» D. secondary terminal voltage to primary applied voltage | |
| 41. |
*$_Which winding of the transformer has less cross-sectional area?? |
| A. | Primary winding |
| B. | Secondary winding |
| C. | Low voltage winding |
| D. | High voltage winding |
| Answer» E. | |
| 42. |
*$_Natural air cooling is generally restricted for transformers up to? |
| A. | 1.5 MVA |
| B. | 5 MVA |
| C. | 15 MVA |
| D. | 50 MVA |
| Answer» B. 5 MVA | |
| 43. |
*$_The chemical used in breather is? |
| A. | asbestos fiber |
| B. | silica sand |
| C. | sodium chloride |
| D. | silica gel |
| Answer» E. | |
| 44. |
*$_The highest voltage for transmitting electrical power in India is? |
| A. | 33 kV |
| B. | 66 kV |
| C. | 132 kV |
| D. | 400 kV |
| Answer» E. | |
| 45. |
*$_Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in? |
| A. | short-circuiting of the secondaries |
| B. | power factor of one of the transformers is leading while that of the other lagging |
| C. | transformers having higher copper losses will have negligible core losses |
| D. | loading of the transformers not in proportion to their kVA ratings |
| Answer» E. | |
| 46. |
*$_Delta/star transformer works satisfactorily when? |
| A. | load is balanced only |
| B. | load is unbalanced only |
| C. | on balanced as well as unbalanced loads |
| D. | none of the above |
| Answer» D. none of the above | |
| 47. |
*$_Part of the transformer which is most subject to damage from overheating is? |
| A. | iron core |
| B. | copper winding |
| C. | winding insulation |
| D. | frame or case |
| Answer» D. frame or case | |
| 48. |
*$_Helical coils can be used on? |
| A. | low voltage side of high kVA transformers |
| B. | high frequency transformers |
| C. | high voltage side of small capacity transformers |
| D. | high voltage side of high kVA rating transformers |
| Answer» B. high frequency transformers | |
| 49. |
*$_The thickness of laminations used in a transformer is usually? |
| A. | 0.4 mm to 0.5 mm |
| B. | 4 mm to 5 mm |
| C. | 14 mm to 15 mm |
| D. | 25 mm to 40 mm |
| Answer» B. 4 mm to 5 mm | |
| 50. |
*$_Power transformers are designed to have maximum efficiency at? |
| A. | nearly full load |
| B. | 70% full load |
| C. | 50% full load |
| D. | no load |
| Answer» B. 70% full load | |