Top 80+ Solved Transformers MCQ Questions Answer
Q. Helical coils can be used on
a. low voltage side of high kVA trans¬formers
b. high frequency transformers
c. high voltage side of small capacity transformers
d. high voltage side of high kVA rating transformers
Q. Harmonics in transformer result in
a. increased core losses
b. increased I2R losses
c. magnetic interference with communication circuits
d. all of the above
Q. The core used in high frequency transformer is usually
a. copper core
b. cost iron core
c. air core
d. mild steel core
Q. The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss willbe
a. 6400 W
b. 1600 W
c. 800 W
d. 400 W
Q. The value of flux involved m the e.m.f. equation of a transformer is
a. average value
b. r.m.s. value
c. maximum value
d. instantaneous value
Q. Silicon steel used in laminations mainly reduces
a. hysteresis loss
b. eddy current losses
c. copper losses
d. all of the above
Q. Which winding of the transformer has less cross-sectional area ?
a. Primary winding
b. Secondary winding
c. Low voltage winding
d. High voltage winding
Q. Power transformers are generally designed to have maximum efficiency around
a. no-load
b. half-load
c. near full-load
d. 10% overload
Q. Which of the following is the main advantage of an auto-transformer over a twowinding transformer ?
a. Hysteresis losses are reduced
b. Saving in winding material
c. Copper losses are negligible
d. Eddy losses are totally eliminated
Q. During short circuit test iron losses are negligible because
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
Q. 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 trans¬formers 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
Q. 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
Q. An ideal transformer is one which has
a. no losses and magnetic leakage
b. interleaved primary and secondary windings
c. a common core for its primary and secondary windings
d. core of stainless steel and winding of pure copper metal
Q. 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
Q. In an actual transformer the iron loss remains practically constant from noload tofullload 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