Transformer MCQS Part -05



1 Which of the given test determine the iron loss of the transformer?

A. Short circuit test
B. Back-to-back test
C. Open circuit test
D. Both option a & b

Answer: C


2 The frictional loss in a transformer is

A. 10 %
B. 50 %
C. 0 %
D. More than 50 %

Answer: C


3 Which type of winding is used in the three-phase shell type transformer

A. Square type
B. Circular type
C. Sandwich type
D. Cylindrical type

Answer: C


4 Which of the given winding of the transformer has less cross-sectional area?

A. Primary winding
B. Low voltage winding
C. High voltage winding
D. Secondary winding

Answer: C


5 The secondary winding of which of the given transformer is always kept closed

A. Voltage transformer
B. Current transformer
C. Step-up transformer
D. Power transformer

Answer: B


6 Which of the given losses changes with the load in the transformer?

A. Copper loss
B. Iron loss
C. Core loss
D. None of these

Answer: A


7. The function of breather in a transformer is

A.to provide oxygen inside the tank
B.to cool the coils during reduced load
C.to cool the transformer oil
D.to arrest flow of moisture when outside air enters the transformer

Answer: D

8. 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

Answer: D

9.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

Answer: C

10. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are

A.friction and windage losses
B.copper losses
C.hysteresis and eddy current losses
D.none of the above

Answer: C

11. The changes in volume of transformer cooling oil due to variation of atmospheric tem-perature during day and night is taken care of by which part of transformer

A.Conservator
B.Breather
C.Bushings
D.Buchholz relay

Answer: A

12. Star/star transformers work satisfactorily when

A.load is unbalanced only
B.load is balanced only
C.on balanced as well as unbalanced loads
D.none of the above

Answer: B

13. Delta/star transformer works satisfactorily when

A.load is balanced only
B.load is unbalanced only
C.on balanced as well as unbalanced loads
D.none of the above

Answer: C

14. In a transformer the resistance between its primary and secondary should be

A.zero
B.10 OHM
C.1000 OHM
D.infinity

Answer: D

15. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds

A.50°C
B.80°C
C.100°C
D.150°C

Answer: D

16. For given applied voltage, with the increase in frequency of the applied voltage

A.eddy current loss will decrease
B.eddy current loss will increase
C.eddy current loss will remain unchanged
D.none of the above

Answer: C

17. In an actual transformer the iron loss remains practically constant from noload to fullload 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

Answer: C

18. The chemical used in breather is

A.asbestos fiber
B.silica sand
C.sodium chloride
D.silica gel

Answer:  D



19. In case of a double cage induction motor, the inner cage has

A.high inductance arid low resistance
B.low inductance and high resistance
C.low inductance and low resistance
D.high inductance and high resistance


Answer:  A


20. If the supply frequency to the transformer is increased, the iron loss will

A.not change
B.decrease
C.increase
D.any of the above


Answer:  C


21.The term 'cogging' is associated with

A.three phase transformers
B.compound generators
C.series motors
D.induction motors


Answer:  D


22. Minimum voltage regulation occurs when the power factor of the load is

A.unity
B.lagging
C.leading
D.zero


Answer:  C



23. The highest voltage for transmitting electrical power in India is

A.33 kV
B.66 kV
C.132 kV
D.400 kV


Answer:  D


24. The secondary winding of which of the following transformers is always kept closed?

A.Step-up transformer
B.Step-down transformer
C.Potential transformer
D.Current transformer


Answer:  D


25. 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


Answer:  A


26. The transformer oil should have _____ volatility and _____ viscosity.

A.low,low
B.high,high
C.low,high
D.high,low

Answer:  A


27. The degree of mechanical vibrations produced by the laminations of a transformer depends on

A.tightness of clamping
B.gauge of laminations
C.size of laminations
D.all of the above


Answer:  D


28. The thickness of laminations used in a transformer is usually

A.0.4 mm to 0.5 mm
B.4 mm to 5 mm
C.14 mm to 15 mm
D.25 mm to 40 mm


Answer: A



29. The core used in high frequency transformer is usually

A.copper core
B.cost iron core
C.air core
D.mild steel core


Answer:  C


30. A transformer transforms

A.voltage
B.current
C.power
D.frequency


Answer:  C


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