29. Transformer oil must be free from
A. odour
B. gases
C. sulphur
D. moisture

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30. Which of the following parts of a transformer is likely to suffer maximum damage due to excessive temperature rise?
A. copper windings
B. core laminations
C. dielectric strength of oil
D. winding isulation

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31.  The magnetising current of a trans former is usually small because it has
A. laminated silicon steel core
B. small air gap
C. nor rotating part
D. large leakage flux

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32. In a power transformer, conservator takes care of
A. expansion and contraction of oil
B. atmospheric temperature variation
C. atmospheric humidity variation
D. load fluctuations

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33. Which of the following will improve the mutual coupling between primary and secondary of a transformer?
A. high reluctance magnetic core
B. transformer oil of hight breakdown voltage
C. winding material of high resistivity
D. low reluctance magnetic core

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34. Transformer oil used in transformer provides
A. insulation and cooling
B. cooling and lubrication
C. lubrication and insulation
D. insulation, cooling and lubrication

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35. The size of transformer core depends on
A. frequency
B. area of the core
C. flux density of core material
D. both (a) and (c) above

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