Transformers Objective Questions: Part-8

[1] The degree of mechanical vibrations produced by the laminations of a transformers depends on
A. Tightness of clamping
B. Gauge of laminations
C. Size of laminations
D. All of the above

Ans: D

[2] The no-load current drawn by transformer is usually........percent of the full-load current?
A. 0.2 to 0.5 %
B. 2 to 5%
C. 12 to 15 %
D. 20 to 30 %

Ans:B

[3] The dielectric strength of transformer oil is expected to be
A. 1kV
B. 33kV
C. 100kV
D. 330 kV

Ans: B

[4] During the short-circuit test on a small transformer the frequency is increased from 50-200Hz. The copper losses will increase by a factor of
A. 16
B. 4
C. 1
D. 1/4

Ans:A

[5] No-load current in a transformer
A. Lags behind the voltage by about 75 deg
B. Leads the voltage by about 75
C. Lags behind the voltage by about 15
D. Leads the voltage by about 15

Ans:A

[6] 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

[7] The chemical used in breather for transformer should have the quality of
A. Ionizing air
B. Absorbing moisture
C. Cleansing the transformer oil
D. Cooling the transformer oil

Ans:B

[8] If a pump motor is run on 2/3rd of its supply voltage, it will
A. Continue to deliver same power
B. Burn
C. Stall
D. Continue to run at lower speed

Ans:C

[9] An ideal transformer has infinite values of primary and secondary inductances. The statement is
A. True
B. False

Ans: B

[10] The noise resulting from vibrations of laminations set by magnetic force, is termed as
A. Magnetostriction
B. Boo
C. Hum
D. Zoom

Ans:C

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