A. load changes
B. oil in the transformer
C. magnetostriction
D. mechanical vibrations
Related Mcqs:
- Which of the following is the main advantage of an auto-transformer over a two winding transformer?
A. Hysteresis losses are reduced
B. Saving in winding material
C. Copper losses are negligible
D. Eddy losses are totally eliminated - 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 - In the transformer following winding has got more cross-sectional area______________?
A. Low voltage winding
B. High voltage winding
C. Primary winding
D. Secondary winding - In the transformer the function of a conservator is to_______________?
A. provide fresh air for cooling the transformer
B. supply cooling oil to transformer in time of need
C. protect the transformer from damage when oil expends due to heating
D. none of the above - 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 - The value of flux involved m the e.m.f. equation of a transformer is____________?
A. average value
B. r.m.s. value
C. maximum value
D. instantaneous value - 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 - The efficiency of a transformer, under heavy loads, is comparatively low because_______________?
A. copper loss becomes high in proportion to the output
B. iron loss is increased considerably
C. voltage drop both in primary and secondary becomes large
D. secondary output is much less as compared to primary input - If a transformer is switched on to a voltage more than the rated voltage______________?
A. its power factor will deteriorate
B. its power factor will increase
C. its power factor will remain unaffected
D. its power factor will be zero - For a transformer, operating at constant load current, maximum efficiency will occur at______________?
A. 0.8 leading power factor
B. 0.8 lagging power factor
C. zero power factor
D. unity power factor
