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
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
Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?
(A) 50°C
(B) 80°C
(C) 100°C
(D) 150°C
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
A Buchholz relay can be installed on______________?
(A) auto-transformers
(B) air-cooled transformers
(C) welding transformers
(D) oil cooled transformers
The core used in high frequency transformer is usually___________?
(A) copper core
(B) cost iron core
(C) air core
(D) mild steel core
In a transformer the resistance between its primary and secondary is____________?
(A) zero
(B) 1 ohm
(C) 1000 ohms
(D) infinite
Harmonics in transformer result in___________?
(A) increased core losses
(B) increased I2R losses
(C) magnetic interference with communication circuits
(D) all of the above
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