Hi friends, this post is about transformer objectives. These are some of the questions asked in previous question papers of Gate, IES and other competitive exams. check out and comment if you have any doubts.....
1) In a power transformer, the breather is provided in order to
A) filter transformer oil
B) prevent ingress of moisture in the oil
C) provide oxygen to the cooling oil
D) provide fresh air for increasing cooling effect
Ans:B
2) A Buchholz relay is used for
A) protection of a transformer against all internal faults
B) protection of a transformer against external faults
C) protection of a transformer against both internal and external faults
D) protection of induction motors
Ans:A
3) Malfunctioning of the relay may be caused due to
A) heavy external short circuits
B) improper breather action
C) dropping of oil level below the relay level during operation
D) excessive overheating
Ans:C
4) A shell type transformer is commonly used as it has
A) two magnetic paths
B) reduced magnetic flux leakage
C) reduce copper losses
D) both (A) and (B)
Ans:D
5) Natural air cooling is used for transformers of rating up to
A) 100 KVA
B) 500 KVA
C) 5-10 KVA
D) 10 MVA
Ans:C
6) The chemical used in breather of a transformer should have the quality of
A) absorbing moisture
B) ionizing air
C) cleansing the transformer oil
D) none of the above
Ans:A
7) Which part of transformer is subjected to maximum heating?
A) Frame
B) Core
C) Winding
D) Oil
Ans:C
8) For core type power transformers, both primary and secondary winding have circular coil sections as it
A) reduces core material requirement and so also reduces the core loss
B) gives the strongest mechanical shape
C) is easier to wind
D) reduces the copper requirement
Ans:B
9) The function of oil in a transformer is
A) to provide insulation and cooling
B) to provide protection against lightning
C) to provide protection against short circuit
D) to provide lubrication
Ans:A
10) The transformer oil should have
A) low volatility
B) high dielectric strength
C) good resistance to emulsion with water
D) low viscosity to provide good heat transfer
E) all of the above
Ans:E
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