Transformers Multiple Choice Questions and Answers, Objective Questions and Answers

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TOP Transformers – Electrical Engineering Multiple Choice Questions and Answers

1.  Which of the following does not change in a transformer ?
(a)  Current
(b) Voltage
(c) Frequency
(d) All of the above
Ans: c

2.  In a transformer the energy is conveyed from primary to secondary
(a) through cooling coil
(b) through air
(c) by the flux
(d) none of the above
Ans: c

3. A transformer core is laminated to
(a) reduce hysteresis loss
(b) reduce eddy current losses
(c) reduce copper losses
(d) reduce all above losses
Ans: b

4. 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
Ans: d

5. The no-load current drawn by transformer is usually what per cent of the full-load current ?
(a) 0.2 to 0.5 per cent
(b) 2 to 5 per cent
(c) 12 to 15 per cent
(d) 20 to 30 per cent
Ans: b

6. The path of a magnetic flux in a transformer should have
(a) high resistance
(b) high reluctance
(c) low resistance
(d) low reluctance
Ans: d

7. No-load on a transformer is carried out to determine
(a) copper loss
(b) magnetising current
(c) magnetising current and loss
(d) efficiency of the transformer
Ans: c

8. The dielectric strength of transformer oil is expected to be
(a)  lkV
(b)  33 kV
(c)  100 kV
(d) 330 kV
Ans: b

9.   Sumpner’s test is conducted on trans-formers to determine
(a)     temperature
(b)     stray losses
(c) all-day efficiency
(d) none of the above
Ans: a

10. The permissible flux density in case of cold rolled grain oriented steel is around
(a) 1.7 Wb/m2
(b) 2.7 Wb/m2
(c) 3.7 Wb/m2
(d) 4.7 Wb/m2
Ans: a

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