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.Management Sciences
Category: Transformers
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
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°
Noise level test in a transformer is a______________?
A. special test
B. routine test
C. type test
D. none of the above
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
Minimum voltage regulation occurs when the power factor of the load is_____________?
A. unity
B. lagging
C. leading
D. zero
The hum in a transformer is mainly attributed to______________?
A. load changes
B. oil in the transformer
C. magnetostriction
D. mechanical vibrations
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
Which winding in a transformer has more number of turns ?
A. Low voltage winding
B. High voltage winding
C. Primary winding
D. Secondary winding
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be___________?
A. 6400 W
B. 1600 W
C. 800 W
D. 400 W
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
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