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Electrical Engineering Objective Questions { Transformers }

36. For large power transformer, best utilization of available core space can be made by using
A. rectangular core section
B. square core section
C. stepped core section
D. none of these

37. Five limb core construction of a transformer has advantage over three limb core construction that
A. eddy current loss is less
B. magnetic reluctance of the three phases can be balanced
C. hysteresis loss is less
D. permeability is higher

38. Transformer windings are tapped in the middle because
A. it reduces insulation requirement
B. it eliminates axial forces on the windings
C. it eliminates radial forces on the winding
D. none of these

39.  For large power transformers, it is preferred to use
A. tubed tanks
B. corrugated tanks
C. radiator tanks
D. tanks with separate coolers

40. Oil natural cooling with tubes is used for transformers of capacity upto
A. 50 kVA
B. 500 kVA
C. 1000 kVA
D. 10,000 kVA

41. Air blast cooling is provided for transformers of capacity exceeding
A. 500 kVA
B. 1000 kVA
C. 3000 kVA
D. 10,000 kVA

42.  In a transformer with closed magnetic coupling between primary and secondary windings
A. efficiency will be high
B. all day efficiency will be high
C. regulation will be good
D. none of these

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