Which of the following does not change in an ordinary transformer ?
Which of the following does not change in an ordinary transformer ?
A. Frequency
B. Voltage
C. Current
D. Any of the above
Transformers
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The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?
The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?
A. Conservator
B. Breather
C. Bushings
D. Buchholz relay -
The magnetising current of a transformer is usually small because it has___________?
The magnetising current of a transformer is usually small because it has___________?
A. small air gap
B. large leakage flux
C. laminated silicon steel core
D. fewer rotating parts -
Buchholz’s relay gives warning and protection against_________________?
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 -
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in____________?
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 -
During short circuit test iron losses are negligible because of _____________?
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 -
Which of the following is the main advantage of an auto-transformer over a two winding transformer?
Which of the following is the main advantage of an auto-transformer over a two winding transformer?
A. Hysteresis losses are reduced
B. Saving in winding material
C. Copper losses are negligible
D. Eddy losses are totally eliminated -
Power transformers are generally designed to have maximum efficiency around__________?
Power transformers are generally designed to have maximum efficiency around__________?
A. no-load
B. half-load
C. near full-load
D. 10% overload -
Which winding of the transformer has less cross-sectional area?
Which winding of the transformer has less cross-sectional area?
A. Primary winding
B. Secondary winding
C. Low voltage winding
D. High voltage winding -
Silicon steel used in lamination’s mainly reduces___________?
Silicon steel used in lamination’s mainly reduces___________?
A. hysteresis loss
B. eddy current losses
C. copper losses
D. all of the above