multiple choice questions on transformer # 15

                           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) Two transformers when operating in parallel will share the load depending upon which of the following
A) Magnetizing current
B) Leakage reactance
C) per unit impedance
D) Efficiency

Ans:C

2) Over currents in a transformer adversely affect
A) insulation life
B) mechanical stress
C) both (a) and (b)
D) none of these

Ans:C

3)  If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then
A) both hysteresis loss and eddy current loss in the core will increase
B) hysteresis loss will increase but eddy current loss will decrease
C) hysteresis loss will decrease but eddy current loss will increase
D) hysteresis loss will decrease but eddy current loss will remain unchanged

Ans:D

4) In a 100 KVA, 1100/200 V, 50 Hz single phase transformer with 2000 turns on high voltage side, the open circuit test result gives 220 V, 91 A, 5KW on low voltage side. The core loss component of current is approximately
A) 9.1 A
B) 22.7 A
C) 45.0 A
D) 91 A

Ans:B

5) The nominal short circuited voltage of a transformer means of
A) voltage across the primary terminals when the secondary terminals are short circuited
B) voltage appearing across the secondary terminals when they are short circuited
C) primary voltage when the secondary terminals are short circuited and the rated current flows through the primary winding
D) none of the above

Ans:C

6) In a single phase transformer the magnitude of leakage reactance is twice that of resistance of both primary and secondary. With secondary short circuited, the input power factor is
A) 1/√2
B) 1/√5
C) 2/√5
D) 1/3

Ans:B

7) While performing the open circuit and short circuit tests on a transformer to determine parameters the status of the low voltage(LV) and high voltage (HV) winding will be such that
A) in OC, LV is open and in SC HV is shorted
B) in OC, HV is open and in SC LV is shorted
C) in OC, LV is open and in SC LV is shorted
D) in OC, HV is open and in SC HV is shorted

Ans:B

8) Which of the following connection of transformer will give the highest secondary voltage?
A) Delta primary , delta secondary
B) Delta primary , star secondary
C) star primary , star secondary
D) star primary , delta secondary

Ans:B

9) Five limb construction is preffered over three limb construction as in this type of construction
A) hysteresis loss is reduced
B) eddy current loss is reduced
C) magnetic reluctance of the three phase can be balanced
D) copper losses are reduced

Ans:C

10) Which of the following 3-phase connections of a transformer causes interference to the near by communication systems?
A) Delta-star
B) Star-delta
C) Star-star
D) Delta-delta

Ans:C

                       If you like my post share it with your friends and subscribe for latest updates..

• Twitter
• Facebook
• Google
• Tumblr
• Pinterest