148.  Which winding of the transformer has less cross-sectional area?
A. Primary winding
B. Secondary winding
C. Low voltage winding
D. High voltage winding

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149. Power transformers are generally designed to have maximum efficiency around
A. no-load
B. half-load
C. near full-load
D. 10% overload

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150.  Which of the following is the main advantage of an auto-transformer over a two winding transformer?
A. Hysteresis loses are reduced
B. Saving in winding material
C. Copper losses are negligible
D. Eddy losses are totally eliminated

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151.  During short-circuit test iron losses are negligible because
A. the current on secondary side is negligible
B. the voltage on secondary side does not vary
C. the voltage applied on primary side is low
D. full-load current is not supplied to the transformer

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152.  Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
A. short-circuiting of the secondaries
B. power factor of one of the transformers is leading while that of the other lagging
C. transformers having higher copper losses will have negligible core losses
D. loading of the transformers not in proportion to their kVA ratings

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153. 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

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154.  An ideal transformer is one which has
A. no losses and magnetic leakage
B. interleaved primary and secondary windings
C. a common core for its primary and secondary windings
D. core of stainless steel and winding of pure copper metal

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