TRANSFORMER MCQS SET 22

TRANSFORMER MCQS SET 22

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