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MCQ of Transformer page-26


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151. The permittivity of transformer oil is about

A) 1.0
B) 2.2
C) 22
D) 44.

Ans : (C)

152. The relative permittivity of bakelite is approximately

A) 1.0
B) 2.2
C) 4.4
D) 44.

Ans : (D)

153. In a large capacity transformer, 5% of the turns at the ends of high voltage winding are provided with extra insulation to

A) Provide protection against lightning
B) Provide protection against corona
C) Provide protection due to surges occurring during switching operations
D) For all above protections.

Ans : (C)

154. In Scott connections, the neutral point divides the teaser winding in the ratio

A) 1 : 3
B) 1 : 2
C) 1 : 1
D) 1 : 4.

Ans : (A)

155. Scott connections are used for

A) single phase to there phase transformation
B) three phase to single phase transformation
C) three phase to three phase and three phase to two phase transformation
D) any of the above.

Ans : (C)

156. Hysteresis losses are present in iron core coil when

A) the current is unsymmetrical alternating
B) the current in the coil is sinusoidal only
C) the current in the coil is DC only
D) the current in the coil is alternating.

Ans : (D)

157. Low voltage windings are placed next to the core as in this case _ is reduced.

A) Hysteresis loss
B) Eddy current loss
C) Insulation requirement
D) Copper loss.

Ans : (C)

158. Which of the following can be reduced when the flux density in the transformer core is increased ?

A) Size of transformer
B) Output frequency
C) Wave shape distortion
D) Copper losses.

Ans : (A)

159. In Scott connection, the neutral point divides the winding of the Teaser transformer in the ratio of

A) 1 : 1
B) 1 : 2
C) 1 : 3
D) 1 : 4.

Ans : (B)

160. Which of the following test can be used to determine the efficiency of two identical transformers at full load ?

A) Open-circuit test
B) Short circuit test
C) Type tests
D) Back to back test.

Ans : (D)


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