Multiple Choice Questions (MCQ) on Transformers
1- In two winding transformers, primary and secondary windings are
(A) conductively linked
(B) inductively linked
(C) electrically linked
(D) not linked at all
2- The core flux of a practical transformer with a resistive load
(A) is constant with load changes
(B) increases linearly with load
(C) increases as the square root of load
(D) decreases with increase in load
3- The flux in the transformer core
(A) increases with increase in load
(B) decreases with decrease in load
(C) remains constant irrespective of load
(D) decreases with increase in load
4- Full load voltage regulation of a transformer is zero when the power factor of the load is near
(A) unity and leading
(B) zero and leading
(C) zero and lagging
(D) unity and lagging
5- All day efficiency of a distribution transformer is ___ the commercial efficiency
(A) the same as
(B) more than
(C) less than
(D) none of the above
6- Open circuit test on a transformer gives
(A) hysteresis loss
(B) eddy current loss
(C) copper loss
(D) sum of hysteresis and eddy current loss
7- Transformer offers negative voltage regulation when its operating power factor is
(A) zero
(B) leading
(C) lagging
(D) unity
8- The percentage differential protection of a transformer protects the transformer against
(A) external faults
(B) internal faults
(C) magnetizing current inrush
(D) overloading
9- The transformer that should never have the secondary open circuited when the primary is energized, is the
(A) power transformer
(B) voltage transformer
(C) auto transformer
(D) current transformer
10- To prevent mal-operation of differentially connected relay while energizing a transformer, the relay restraining coil is biased with
(A) second harmonic current
(B) third harmonic current
(C) fifth harmonic current
(D) seventh harmonic current
ANSWERS:
1-(B), 2-(A), 3-(C), 4-(A), 5-(C), 6-(D), 7-(B), 8-(B), 9-(D), 10-(A)