TRANSFORMER MCQS SET 23

TRANSFORMER MCQS SET 23

1. The efficiency of a transformer will be maximum when
(a) copper losses = hysteresis losses    
(b) hysteresis losses = eddy current losses
(c) eddy current losses = copper losses
(d) copper losses = iron losses
Ans: d
 

2. No-load current in a transformer
(a) lags behind the voltage by about 75°
(b) leads the voltage by about 75°
(c) lags behind the voltage by about 15°
(d) leads the voltage by about 15°
Ans: a
 

3. The purpose of providing an iron core in a transformer is to
(a) provide support to windings
(b) reduce hysteresis loss
(c) decrease the reluctance of the magnetic path
(d) reduce eddy current losses
 Ans: c
 

4. Which of the following is not a part of transformer installation?
(a) Conservator      (b) Breather    c) Buchholz relay  (d) Exciter
Ans: d
 

5. While conducting short-circuit test on a transformer the following side is short circuited
(a) High voltage side   (b) Low voltage side     (c) Primary side
(d) Secondary side
Ans: b
 

6. In the transformer following winding has got more cross-sectional area
(a) Low voltage winding        (b) High voltage winding
(c) Primary winding             (d) Secondary winding
Ans: a
 

7. A transformer transforms
(a) voltage   (b) current         (c) power          (d) frequency
Ans: c
 

8. A transformer cannot raise or lower the voltage of a D.C. supply because
(a) there is no need to change the D.C. voltage
(b) a D.C. circuit has more losses
(c) Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero
(d) none of the above
Ans: c
 

9. Primary winding of a transformer
(a) is always a low voltage winding
(b) is always a high voltage winding
(c) could either be a low voltage or high voltage winding
(d) none of the above
Ans: c  

10. Which winding in a transformer has more number of turns ?
(a) Low voltage winding         (b) High voltage winding
(c) Primary winding              (d) Secondary winding
Ans: b