411. The magnetising current of a transformer is usually small because it has___________?
A. small air gap
B. large leakage flux
C. laminated silicon steel core
D. fewer rotating parts
412. 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
413. Which of the following does not change in an ordinary transformer ?
A. Frequency
B. Voltage
C. Current
D. Any of the above
414. 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
E. none of the above
415. The leakage flux in a transformer depends upon______________?
A. load current
B. load current and voltage
C. load current, voltage and frequency
D. load current, voltage, frequency and power factor
416. 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
417. When a given transformer is run at its rated voltage but reduced frequency, its____________?
A. flux density remains unaffected
B. iron losses are reduced
C. core flux density is reduced
D. core flux density is increased
418. The path of the magnetic flux in transformer should have____________?
A. high reluctance
B. low reactance
C. high resistance
D. low resistance
419. In an actual transformer the iron loss remains practically constant from no load to full load because:____________?
A. value of transformation ratio remains constant
B. permeability of transformer core remains constant
C. core flux remains practically constant
D. primary voltage remains constant
C. secondary voltage remains constant
420. Noise level test in a transformer is a______________?
A. special test
B. routine test
C. type test
D. none of the above
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