MCQOPTIONS
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MCQOPTIONS
This section includes 113 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Reduction in core losses and increase in permeability are obtained with transformer employing__________? |
| A. | core built-up of laminations of cold rolled grain oriented steel |
| B. | core built-up of laminations of hot rolled sheet |
| C. | either of the above |
| D. | none of the above |
| Answer» B. core built-up of laminations of hot rolled sheet | |
| 52. |
Primary winding of a transformer________________? |
| A. | is always a low voltage winding |
| B. | is always a high voltage winding |
| C. | could either be a low voltage or high voltage winding |
| D. | none of the above |
| Answer» D. none of the above | |
| 53. |
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 | |
| 54. |
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 | |
| 55. |
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 |
| E. | transformer tank |
| Answer» D. frame or case | |
| 56. |
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 | |
| 57. |
Noise level test in a transformer is a______________? |
| A. | special test |
| B. | routine test |
| C. | type test |
| D. | none of the above |
| Answer» D. none of the above | |
| 58. |
No-load on a transformer is carried out to determine______________? |
| A. | copper loss |
| B. | magnetising current |
| C. | magnetising current and loss |
| D. | efficiency of the transformer |
| Answer» D. efficiency of the transformer | |
| 59. |
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. | |
| 60. |
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° | |
| 61. |
Negative voltage regulation is indicative that the load is___________? |
| A. | capacitive only |
| B. | inductive only |
| C. | inductive or resistive |
| D. | none of the above |
| Answer» B. inductive only | |
| 62. |
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 | |
| 63. |
N atural air coo ling is generally restricted for transformers up to__________? |
| A. | 1.5 MVA |
| B. | 5 MVA |
| C. | 15 MVA |
| D. | 50 MVA |
| Answer» B. 5 MVA | |
| 64. |
Minimum voltage regulation occurs when the power factor of the load is_____________? |
| A. | unity |
| B. | lagging |
| C. | leading |
| D. | zero |
| Answer» D. zero | |
| 65. |
Material used for construction of transformer core is usually___________________? |
| A. | wood |
| B. | copper |
| C. | aluminium |
| D. | silicon steel |
| Answer» E. | |
| 66. |
Losses which occur in rotating electric machines and do not occur in transformers are___________? |
| A. | friction and windage losses |
| B. | magnetic losses |
| C. | hysteresis and eddy current losses |
| D. | copper losses |
| Answer» B. magnetic losses | |
| 67. |
Iron loss of a transformer can be measured by____________? |
| A. | low power factor wattmeter |
| B. | unity power factor wattmeter |
| C. | frequency meter |
| D. | any type of wattmeter |
| Answer» B. unity power factor wattmeter | |
| 68. |
In the transformer the function of a conservator is to_______________? |
| A. | provide fresh air for cooling the transformer |
| B. | supply cooling oil to transformer in time of need |
| C. | protect the transformer from damage when oil expends due to heating |
| D. | none of the above |
| Answer» D. none of the above | |
| 69. |
In the transformer following winding has got more cross-sectional area______________? |
| A. | Low voltage winding |
| B. | High voltage winding |
| C. | Primary winding |
| D. | Secondary winding |
| Answer» B. High voltage winding | |
| 70. |
In an actual transformer the iron loss remains practically constant from no load to full load 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 |
| E. | secondary voltage remains constant |
| Answer» D. primary voltage remains constant | |
| 71. |
In a transformer the tappings are generally provided on_____________? |
| A. | primary side |
| B. | secondary side |
| C. | low voltage side |
| D. | high voltage side |
| Answer» E. | |
| 72. |
In a transformer the resistance between its primary and secondary is____________? |
| A. | zero |
| B. | 1 ohm |
| C. | 1000 ohms |
| D. | infinite |
| Answer» E. | |
| 73. |
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 | |
| 74. |
In a transformer the resistance between its primary and secondary should be_____________? |
| A. | zero |
| B. | 10 Q |
| C. | 1000 Q |
| D. | infinity |
| Answer» E. | |
| 75. |
In a transformer routine efficiency depends upon_____________? |
| A. | supply frequency |
| B. | load current |
| C. | power factor of load |
| D. | both B. and (c) |
| Answer» E. | |
| 76. |
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 | |
| 77. |
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 | |
| 78. |
In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are______________? |
| A. | friction and windage losses |
| B. | copper losses |
| C. | hysteresis and eddy current losses |
| D. | none of the above |
| Answer» D. none of the above | |
| 79. |
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are__________? |
| A. | hysteresis and eddy current losses |
| B. | friction and windage losses |
| C. | copper losses |
| D. | none of the above |
| Answer» B. friction and windage losses | |
| 80. |
If the supply frequency to the transformer is increased,”the iron loss will__________? |
| A. | not change |
| B. | decrease |
| C. | increase |
| D. | any of the above |
| Answer» D. any of the above | |
| 81. |
If the percentage impedances of the two transformers working in parallel are different, then______________________? |
| A. | transformers will be overheated |
| B. | power factors of both the transformers will be same |
| C. | parallel operation will be not possible |
| D. | parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the |
| Answer» E. | |
| 82. |
If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be___________? |
| A. | R2/VK |
| B. | R2IK2 |
| C. | R22 |
| D. | R22/K |
| Answer» C. R22 | |
| 83. |
If a transformer is switched on to a voltage more than the rated voltage______________? |
| A. | its power factor will deteriorate |
| B. | its power factor will increase |
| C. | its power factor will remain unaffected |
| D. | its power factor will be zero |
| Answer» B. its power factor will increase | |
| 84. |
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 | |
| 85. |
Hysteresis loss in a transformer varies as CBmax = maximum flux density) ? |
| A. | Bmax |
| B. | Bmax1-6 |
| C. | Bmax1-83 |
| D. | B max |
| Answer» C. Bmax1-83 | |
| 86. |
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 | |
| 87. |
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 | |
| 88. |
Harmonics in transformer result in___________? |
| A. | increased core losses |
| B. | increased I2R losses |
| C. | magnetic interference with communication circuits |
| D. | all of the above |
| Answer» E. | |
| 89. |
Greater the secondary leakage flux____________? |
| A. | less will be the secondary induced e.m.f. |
| B. | less will be the primary induced e.m.f. |
| C. | less will be the primary terminal voltage |
| D. | none of the above |
| Answer» B. less will be the primary induced e.m.f. | |
| 90. |
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 | |
| 91. |
For given applied voltage, with the increase in frequency of the applied voltage? |
| A. | eddy current loss will decrease |
| B. | eddy current loss will increase |
| C. | eddy current loss will remain unchanged |
| D. | none of the above |
| Answer» D. none of the above | |
| 92. |
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. | |
| 93. |
Efficiency of a power transformer is of the order of________________? |
| A. | 100 per cent |
| B. | 98 per cent |
| C. | 50 per cent |
| D. | 25 per cent |
| Answer» C. 50 per cent | |
| 94. |
During short circuit test iron losses are negligible because of _____________? |
| A. | the current on secondary side is negligible |
| B. | the voltage on secondary side does not vary |
| C. | the voltage applied on primary side is low |
| D. | full-load current is not supplied to the transformer |
| Answer» D. full-load current is not supplied to the transformer | |
| 95. |
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 | |
| 96. |
Distribution transformers are generally designed for maximum efficiency around________________? |
| A. | 90% load |
| B. | zero load |
| C. | 25% load |
| D. | 50% load |
| Answer» E. | |
| 97. |
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 | |
| 98. |
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 | |
| 99. |
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 | |
| 100. |
An open-circuit test on a transformer is conducted primarily to measure______________? |
| A. | insulation resistance |
| B. | copper loss |
| C. | core loss |
| D. | total loss |
| E. | efficiency |
| Answer» D. total loss | |