multiple choice questions on transformer # 11

                                 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) Silicon content in iron lamination is kept within 5% as it
A) increases hysteresis loss
B) increases cost
C) makes the material brittle
D) reduces the curie point

Ans:C

2) When a transformer winding suffer a short circuit, the adjoining turns of the same winding experience
A) an attractive force
B) a repulsive force
C) no force

Ans:A

3) The core and winding of a transformer are put in a steel tank in order to
A) make it suitable for outdoor operation
B) provide protection against mechanical damages and provide additional cooling
C) improve its appearance
D) all of the above

Ans:B

4) The noise, in a transformer ,caused by vibrations of lamination set by magnetic forces, is termed as
A) zoom
B) hum
C) buzz
D) none of these

Ans:B

5) The concentric winding are used in core type transformers with......................winding placed next to the core
A) lv
B) primary
C) hv
D) secondary

Ans:A

6) Under short circuit condition, the winding of a transformer having 5% impedance will experience a radial force
A) 5 times of full load value
B) 20 times of full load value
C) 25 times of full load value
D) 400 times of full load value

Ans:D

7) Ferrite cores are employed in high frequency transformers due to their
A) low resistance
B) high resistance
C) low permeablility
D) high hysteresis loss

Ans:B

8) The leakage flux of primary and secondary winding can be reduced to the minimum by
A) winding primary and secondary coils on separate limbs
B) winding primary and secondary coils one upon the other coaxially
C) increasing the number of turns
D) employing low permeability magnetic material core

Ans:B

9) The use of higher flux density in the transformer design
A) reduces the weight per KVA
B) increases the weight per KVA
C) has no relation with the weight of transformer
D) increases the weight per KW

Ans:A

10) For CRGOS mitred overlap is preferred for the core-yoke joints as it
A) reduces the magnetizing current and also the core losses
B) improves the mechanical strength
C) reduces magnetostriction
D) makes better use of core space

Ans:A

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