TRANSFORMER MCQS SET 28

TRANSFORMER MCQS SET 28

1. Buchholz's relay gives warning and protection against
(a) electrical fault inside the transformer itself
(b) electrical fault outside the transformer in outgoing feeder
(c) for both outside and inside faults
(d) none of the above
Ans: a
 

2. The magnetising current of a transformer is usually small because it has
(a) small air gap        (b) large leakage flux
(c) laminated silicon steel core          (d) fewer rotating parts
Ans: a
 

3. Which of the following does not change in an ordinary transformer ?
(a) Frequency     (b) Voltage         (c) Current       (d) Any of the above 

Ans: a
 

4. Which of the following properties is not necessarily desirable for the material for transformer core ?
(a) Low hysteresis loss                   (b) High permeability
(c) High thermal conductivity (d) Adequate mechanical strength 

Ans: c
 

5. The leakage flux in a transformer depends upon
(a) load current              (b) load current and voltage
(c) load current, voltage and frequency
(d) load current, voltage, frequency and power factor
 Ans: a
 

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

7. Noise level test in a transformer is a
(a) special test      (b) routine test        (c) type test        (d) none
Ans: c  

8. Which of the foJIowing is not a routine test on transformers ?
(a) Core insulation voltage test        (b) Impedance test
(c) Radio interference test              (d) Polarity test
Ans: c
 

9. A transformer can have zero voltage regulation at
(a) leading power factor        (b) lagging power factor
(c) unity power factor              (d) zero power factor
 Ans: a
 

10. Helical coils can be used on
(a) low voltage side of high kVA trans¬formers
(b) high frequency transformers
(c) high voltage side of small capacity transformers
(d) high voltage side of high kVA rating transformers
Ans: a