MCQOPTIONS
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MCQOPTIONS
This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
*$_A Buchholz relay can be installed on? |
| A. | auto-transformers |
| B. | air-cooled transformers |
| C. | welding transformers |
| D. | oil cooled transformers |
| Answer» E. | |
| 2. |
*$_For the parallel operation of single phase transformers it is necessary that they should have? |
| A. | same efficiency |
| B. | same polarity |
| C. | same kVA rating |
| D. | same number of turns on the secondary side. |
| Answer» C. same kVA rating | |
| 3. |
*$_The efficiency of a transformer will be maximum when? |
| A. | copper losses = hysteresis losses |
| B. | hysteresis losses = eddy current losses |
| C. | eddy current losses = copper losses |
| D. | copper losses = iron losses |
| Answer» E. | |
| 4. |
*/*_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 | |
| 5. |
*/*_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 | |
| 6. |
*/*_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 | |
| 7. |
*/*_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 | |
| 8. |
*/*_A transformer can have regulation closer to zero? |
| A. | on full-load |
| B. | on overload |
| C. | on leading power factor |
| D. | on zero power factor |
| Answer» D. on zero power factor | |
| 9. |
*/*_The degree of mechanical vibrations produced by the laminations of a transformer depends on? |
| A. | tightness of clamping |
| B. | gauge of laminations |
| C. | size of laminations |
| D. | all of the above |
| Answer» E. | |
| 10. |
*/*_For a transformer, operating at constant load current, maximum efficiency will occur at? |
| A. | 0.8 leading power factor |
| B. | 0.8 lagging power factor |
| C. | zero power factor |
| D. | unity power factor |
| Answer» E. | |
| 11. |
*/*_Star/star transformers work satisfactorily when? |
| A. | load is unbalanced only |
| B. | load is balanced only |
| C. | on balanced as well as unbalanced loads |
| D. | none of the above |
| Answer» C. on balanced as well as unbalanced loads | |
| 12. |
*/*_The function of breather in a transformer is? |
| A. | to provide oxygen inside the tank |
| B. | to cool the coils during reduced load |
| C. | to cool the transformer oil |
| D. | to arrest flow of moisture when outside air enters the transformer |
| Answer» E. | |
| 13. |
*/*_Minimum voltage regulation occurs when the power factor of the load is? |
| A. | unity |
| B. | lagging |
| C. | leading |
| D. | zero |
| Answer» D. zero | |
| 14. |
*/*_In an actual transformer the iron loss remains practically constant from noload to fullload because? |
| A. | value of transformation ratio remains constant |
| B. | permeability of transformer core remains constant |
| C. | core flux remains practically constant |
| D. | primary voltage remains constant |
| Answer» D. primary voltage remains constant | |
| 15. |
*/*_Which of the following loss in a transformer is zero even at full load ?? |
| A. | Core loss |
| B. | Friction loss |
| C. | Eddy current loss |
| D. | Hysteresis loss |
| Answer» C. Eddy current loss | |
| 16. |
*/*_The transformer laminations are insulated from each other by? |
| A. | mica strip |
| B. | thin coat of varnish |
| C. | paper |
| D. | any of the above |
| Answer» C. paper | |
| 17. |
*/*_When a given transformer is run at its rated voltage but reduced frequency, its? |
| A. | flux density remains unaffected |
| B. | iron losses are reduced |
| C. | core flux density is reduced |
| D. | core flux density is increased |
| Answer» E. | |
| 18. |
*/*_If a transformer is continuously operated the maximum temperature rise will occur in? |
| A. | core |
| B. | windings |
| C. | tank |
| D. | any of the above |
| Answer» C. tank | |
| 19. |
*/*_No-load current in a transformer? |
| A. | lags behind the voltage by about 75° |
| B. | leads the voltage by about 75° |
| C. | lags behind the voltage by about 15° |
| D. | leads the voltage by about 15° |
| Answer» B. leads the voltage by about 75¬¨‚àû | |
| 20. |
*/*_An ideal transformer will have maximum efficiency at a load such that? |
| A. | copper loss = iron loss |
| B. | copper loss < iron loss |
| C. | copper loss > iron loss |
| D. | none of the above |
| Answer» B. copper loss < iron loss | |
| 21. |
*/*_The main reason for generation of harmonics in a transformer could be? |
| A. | fluctuating load |
| B. | poor insulation |
| C. | mechanical vibrations |
| D. | saturation of core |
| Answer» E. | |
| 22. |
*/*_Distribution transformers are generally designed for maximum efficiency around? |
| A. | 90% load |
| B. | Zero load |
| C. | 25% load |
| D. | 50% load |
| Answer» E. | |
| 23. |
*/*_In a power or distribution transformer about 10 per cent end turns are heavily insulated? |
| A. | to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns |
| B. | to absorb the line surge voltage and save the winding of transformer from damage |
| C. | to reflect the line surge and save the winding of a transformer from damage |
| D. | none of the above |
| Answer» B. to absorb the line surge voltage and save the winding of transformer from damage | |
| 24. |
*/*_Natural oil cooling is used for transformers up to a rating of? |
| A. | 3000 kVA |
| B. | 1000 kVA |
| C. | 500 kVA |
| D. | 250 kVA |
| Answer» B. 1000 kVA | |
| 25. |
*/*_A transformer oil must be free from? |
| A. | sludge |
| B. | odour |
| C. | gases |
| D. | moisture |
| Answer» E. | |
| 26. |
*/*_No-load current of a transformer has? |
| A. | has high magnitude and low power factor |
| B. | has high magnitude and high power factor |
| C. | has small magnitude and high power factor |
| D. | has small magnitude and low power factor |
| Answer» E. | |
| 27. |
*/*_The power factor of an induction motor under no-load conditions will be closer to? |
| A. | 0.2 lagging |
| B. | 0.2 leading |
| C. | 0.5 leading |
| D. | unity |
| Answer» B. 0.2 leading | |
| 28. |
*/*_The 'crawling' in an induction motor is caused by? |
| A. | high loads |
| B. | low voltage supply |
| C. | improper design of machine |
| D. | harmonics developed in the motor |
| Answer» E. | |
| 29. |
*/*_Which motor is preferred for use in mines where explosive gases exist?? |
| A. | Air motor |
| B. | Induction motor |
| C. | Shunt motor |
| D. | Synchronous motor |
| Answer» B. Induction motor | |
| 30. |
*/*_Which of the following properties is not necessarily desirable for the material for transformer core?? |
| A. | Low hysteresis loss |
| B. | High permeability |
| C. | High thermal conductivity |
| D. | Adequate mechanical strength |
| Answer» D. Adequate mechanical strength | |
| 31. |
*/*_In a transformer the energy is conveyed from primary to secondary? |
| A. | through cooling coil |
| B. | through air |
| C. | by the flux |
| D. | none of the above |
| Answer» D. none of the above | |
| 32. |
*/*_Which of the following is not a part of transformer installation?? |
| A. | Conservator |
| B. | Breather |
| C. | Buchholz relay |
| D. | Exciter |
| Answer» E. | |
| 33. |
%_No-load current in a transformer_% |
| A. | lags behind the voltage by about 75° |
| B. | leads the voltage by about 75° |
| C. | lags behind the voltage by about 15° |
| D. | leads the voltage by about 15° |
| Answer» B. leads the voltage by about 75¬¨‚àû | |
| 34. |
%_If a transformer is continuously operated the maximum temperature rise will occur in_% |
| A. | core |
| B. | windings |
| C. | tank |
| D. | any of the above |
| Answer» C. tank | |
| 35. |
%_When a given transformer is run at its rated voltage but reduced frequency, its_% |
| A. | flux density remains unaffected |
| B. | iron losses are reduced |
| C. | core flux density is reduced |
| D. | core flux density is increased |
| Answer» E. | |
| 36. |
%_The transformer laminations are insulated from each other by_% |
| A. | mica strip |
| B. | thin coat of varnish |
| C. | paper |
| D. | any of the above |
| Answer» C. paper | |
| 37. |
%_A transformer oil must be free from_% |
| A. | sludge |
| B. | odour |
| C. | gases |
| D. | moisture |
| Answer» E. | |
| 38. |
%_The 'crawling' in an induction motor is caused by_% |
| A. | high loads |
| B. | low voltage supply |
| C. | improper design of machine |
| D. | harmonics developed in the motor |
| Answer» E. | |
| 39. |
%_Which motor is preferred for use in mines where explosive gases exist?_% |
| A. | Air motor |
| B. | Induction motor |
| C. | Shunt motor |
| D. | Synchronous motor |
| Answer» B. Induction motor | |
| 40. |
%_No-load current of a transformer has_% |
| A. | has high magnitude and low power factor |
| B. | has high magnitude and high power factor |
| C. | has small magnitude and high power factor |
| D. | has small magnitude and low power factor |
| Answer» E. | |
| 41. |
%_The power factor of an induction motor under no-load conditions will be closer to_% |
| A. | 0.2 lagging |
| B. | 0.2 leading |
| C. | 0.5 leading |
| D. | unity |
| Answer» B. 0.2 leading | |
| 42. |
%_In a transformer the energy is conveyed from primary to secondary_% |
| A. | through cooling coil |
| B. | through air |
| C. | by the flux |
| D. | none of the above |
| Answer» D. none of the above | |
| 43. |
%_Which of the following is not a part of transformer installation?_% |
| A. | Conservator |
| B. | Breather |
| C. | Buchholz relay |
| D. | Exciter |
| Answer» E. | |
| 44. |
%_Which of the following properties is not necessarily desirable for the material for transformer core?_% |
| A. | Low hysteresis loss |
| B. | High permeability |
| C. | High thermal conductivity |
| D. | Adequate mechanical strength |
| Answer» D. Adequate mechanical strength | |
| 45. |
_ An ideal transformer will have maximum efficiency at a load such that$? |
| A. | copper loss = iron loss |
| B. | copper loss < iron loss |
| C. | copper loss > iron loss |
| D. | none of the above |
| Answer» B. copper loss < iron loss | |
| 46. |
_ Sumpner's test is conducted on transformers to determine$? |
| A. | temperature |
| B. | stray losses |
| C. | all-day efficiency |
| D. | none of the above |
| Answer» B. stray losses | |
| 47. |
_ Insertion of resistance in the rotcir of an induction motor to develop a given torque$? |
| A. | decreases the rotor current |
| B. | increases the rotor current |
| C. | rotor current becomes zero |
| D. | rotor current rernains same |
| Answer» E. | |
| 48. |
_ Star/star transformers work satisfactorily when$? |
| A. | load is unbalanced only |
| B. | load is balanced only |
| C. | on balanced as well as unbalanced loads |
| D. | none of the above |
| Answer» C. on balanced as well as unbalanced loads | |
| 49. |
_ In an actual transformer the iron loss remains practically constant from noload to fullload because$? |
| A. | value of transformation ratio remains constant |
| B. | permeability of transformer core remains constant |
| C. | core flux remains practically constant |
| D. | primary voltage remains constant |
| Answer» D. primary voltage remains constant | |
| 50. |
_ Which of the following loss in a transformer is zero even at full load ?$? |
| A. | Core loss |
| B. | Friction loss |
| C. | Eddy current loss |
| D. | Hysteresis loss |
| Answer» C. Eddy current loss | |