MCQ on Single Phase Transformer

1. The reactance of a transformer depends on

(a) size of the core
(b) size of the tank
(c) leakage flux
(d) all of the above.


Answer: (c) leakage flux
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2. Which winding of the transformer has less cross-sectional area ?

(a) Primary winding
(b) Secondary winding
(c) Low voltage winding
(d) High voltage winding


Answer: (d) High voltage winding
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3. 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 current losses are totally eliminated.


Answer: (b) Saving in winding material
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4. 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.


Answer: (c) the voltage applied on primary side is low
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5. The change 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) Bushings
(c) Buchholz relay


Answer: (a) Conservator
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6. 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


Answer: (a) no losses and magnetic leakage
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7. When a given transformer is run at its rated voltage but reduced frequency, its

(a) flux density remains unaffected
(b) iron lessee are reduced
(c) core flux density is reduced
(d) core flux density is increased.


Answer: (d) core flux density is increased.
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8. 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) increase
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9. Negative voltage regulation is indicative that the load is

(a) capacitive only
(b) inductive only
(c) inductive or resistive
(d) none of the above


Answer: (a) capacitive only
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10. Iron loss of a transformer can be measured by

(a) low power factor wattmeter
(b) unity power factor wattmeter
(c) frequency meter
(d) any type of wattmeter.


Answer: (a) low power factor wattmeter
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11. When secondary of a current trans-former is open-circuited its iron core

(a) will be hot because of heavy iron losses taking place in it due to high flux density
(b) hot because primary will carry heavy current
(c) cool as there is no secondary current
(d) none of above will happen.


Answer: (a) will be hot because of heavy iron losses taking place in it due to high flux density
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12. Which type of winding is used in 3-phase shell type transformer ?

(a) Circular type
(b) Sandwich type
(c) Cylindrical type
(d) Rectangular type.


Answer: (a) Circular type
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13. For the parallel operation of single-phase transformers it is necessary that they should have

(a) same efficiency
(b) same polarity
(c) same kVA rating
(d) same number of turns on the secondary side.


Answer: (b) same polarity
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14. The transformer oil should have………volatility and………. viscosity.

(a) high, high
(b) low, high
(c) low, low
(d) high, low


Answer: (c) low, low
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15. The function of breather in a transformer is

(a) to provide oxygen inside the tank
(b) to cool the coils during reduced load
(c) cool the transformer oil
(d) to arrest flow of moisture when outside air enters the transformer.


Answer: (d) to arrest flow of moisture when outside air enters the transformer.
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16. 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) Current transformer.
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17. The size of a transformer core will depend on

(a) frequency
(b) frequency and area of the core
(c) flux density of the core material.


Answer: (b) frequency and area of the core
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18. Natural air-cooling is generally restricted for transformers, up to

(a) 1.5 MVA
(b) 15 MVA
(c) 50 MVA


Answer: (a) 1.5 MVA
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19. A shell-type transformer has

(a) high eddy current losses
(b) reduced magnetic leakage
(c) negligibly hysteresis losses
(d) none of the above


Answer: (b) reduced magnetic leakage
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20. A transformer can have regulation closer to zero

(a) on full-load
(b) on overload
(c) on leading power factor
(d) on zero power factor.


Answer: (c) on leading power factor
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21.While performing a short-circuit test on a transformer, usually low-voltage side is short-circuited because it has

(a) low insulation
(b) easy access
(c) lower terminal voltage and higher current rating
(d) more number of turns


Answer: (c) lower terminal voltage and higher current rating
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22. The secondary winding of a current transformer whose primary Is carrying current should

(a) not be open-circuited
(b) not be short-circuited
(c) either of the above
(d) none of the above


Answer: (a) not be open-circuited
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23.In large transformers, oil is invariably used in order to

(a) lubricate the core
(b) insulate the core
(c) insulate the coils
(d) none of the above


Answer: (c) insulate the coils
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24.Dust should never be allowed to accumulate on the windings and core of a dry type transformer because it

(a) reduces dissipation of heat
(b) may short-circuit the windings
(c) absorbs oil and grease
(d) tends to corrode the metal surface


Answer: (a) reduces dissipation of heat
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25.Increase in secondary current of a transformer brings about increase in primary current. This is possible because

(a) primary and secondary windings are capacitively coupled
(b) primary and secondary windings are inductively coupled
(c) primary and secondary windings are conductively coupled
(d) none of the above


Answer: (b) primary and secondary windings are inductively coupled
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26.An auto-transformer is preferred to a conventional 2-winding transformer

(a) where ratio of transformation is low
(b) where it is required to isolate the two windings electrically
(c) because it is much safer to use en auto-transformer
(d) where large number of secondary taps are needed


Answer: (a) where ratio of transformation is low
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27.Transformer for constant voltage applications is considered good if its voltage regulation is

(a) low
(b) high
(c) zero
(d) none of the above


Answer: (a) low
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28. Transformer supplying load having negative resistance characteristics such as arc load, is considered if its voltage regulation is

(a) low
(b) high
(c) either of the above
(d) none of the above


Answer: (b) high
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29.For given effective applied voltage of constant frequency eddy current losses

(a) become less with peaked wave shape of applied voltage
(b) independent of the wave shape of the applied voltage
(c) either of the above
(d) none of the above.


Answer: (b) independent of the wave shape of the applied voltage
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30.While rising and while falling, if a wave is symmetrical, it contains

(a) even harmonica in addition to fundamental
(b) odd harmonics in addition to fundamental
(c) both odd and even harmonics in addition to fundamental
(d) none of the above


Answer: (b) odd harmonics in addition to fundamental
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MCQ on Single Phase Transformer

 

  1. Objective Type Questions on Transformer
  2. MCQ Single Phase Transformer
  3. MCQ Questions on Transformer
  4. Transformer MCQ Online Test
  5. Transformer MCQ Questions

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