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.Management Sciences
Category: Transformers
The chemical used in breather is_______________?
A. asbestos fiber
B. silica sand
C. sodium chloride
D. silica gel
In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?
A. to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
B. to absorb the line surge voltage and save the winding of transformer from damage
C. to reflect the line surge and save the winding of a transformer from damage
D. none of the above
A Buchholz relay can be installed on______________?
A Buchholz relay can be installed on
A. auto-transformers
B. air-cooled transformers
C. welding transformers
D. oil cooled transformers
Which of the following property is not necessarily desirable in the material for transformer core ?
A. Mechanical strength
B. Low hysteresis loss
C. High thermal conductivity
D. High permeability
The no-load current drawn by transformer is usually what per cent of the full-load current ?
A. 0.2 to 0.5 per cent
B. 2 to 5 per cent
C. 12 to 15 per cent
D. 20 to 30 per cent
The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?
A. Conservator
B. Breather
C. Bushings
D. Buchholz relay
Which of the following properties is not necessarily desirable for the material for transformer core ?
A. Low hysteresis loss
B. High permeability
C. High thermal conductivity
D. Adequate mechanical strength
Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect?
A. Its secondary current is 5 A
B. Its secondary voltage is 400 V
C. Its rating is 2 kVA
D. Its secondary current is 20 A
E. It is a step-up transformer
Two transformers operating in parallel will share the load depending upon their____________?
A. leakage reactance
B. per unit impedance
C. efficiencies
D. ratings
The efficiencies of transformers compared with that of electric motors of the same power are____________?
A. about the same
B. much smaller
C. much higher
D. somewhat smaller
E. none of the above
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