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Electrical-Transformer Mostly Asked MCQ PDF 2 For RRB JE,SSC JE,UPSSSC Exam

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Electrical-Transformer Mostly Asked MCQ PDF 2 For RRB JE,SSC JE,UPSSSC Exam

1.In a two winding transformer, the primary and secondary induced emf E1 & E2 are always

A. equal in magnitude

B. anti phase with each other

C. in phase with each other

D. determined by load on transformer secondary


2.In a transformer, the leakage flux of each winding is proportional to the current in that winding because

A. Ohm’s law applies to magnetic circuits

B. Leakage paths do no saturate

C. the two windings are electrically isolated

D. mutual flux is confined to the core


3.In a two winding transformer, the emf /turn in secondary winding is always……the induced emf power turn in primary

A. equal to k times

B. equal to 1/k times

C. equal

D. greater than


4.In transformer terminology, the ratio 20:1 indicates that

A. there are 20 turns on primary one turn on secondary

B. secondary voltage is 1/20th of the primary

C. primary current is 20 times greater than the secondary current

D. for every 20 turns on primary, there is one turn on secondary


5.In performing the short circuit test of a transformer

A. high voltage is usually short circuited

B. low voltage side is usually short circuited

C. any side is short circuited with preference

D. none of these


6.In a transformer the energy is conveyed from primary to secondary

A. Through cooling coil

B. Through air

C. By the flux

D. None of these


7.Which loss is not common between a transformer and rotating machines

A. Eddy current loss

B. Copper loss

C. Windage loss

D. Hysteresis loss


8.No load test on a transformer is carried out to find

A. Copper loss

B. magnetising current

C. Magnetising current and loss

D. Efficiency of the transformer


9.Sumpner’s test is conducted on transformers to find

A. Temperature

B. Stray losses

C. All-day efficiency

D. None of these


10.The efficiency of a transformer will be maximum when

A. copper losses = hysteresis losses

B. Hysteresis losses = eddy current losses

C. Eddy current losses = copper losses

D. Copper losses = iron losses


11.The purpose of providing an iron core in a transformer is to

A. Provide support to windings

B. Reduce hysteresis loss

C. decrease the reluctance of the magnetic path

D. reduce eddy current losses


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

A. 33kV

B. 66kV

C. 132kV

D. 400kV


13.The function of conservator in a transformer is

A. To protect against internal fault

B. To reduce copper as well as core losses

C. To cool the transformer oil

D. To take care of the expansion and contraction of transformer oil due to variation of temperature of surroundings


14.The core used in high frequency transformer is usually

A. Copper core

B. Cost iron core

C. Air core

D.Mid steel core


15.Cross over windings are used in

A. Low voltage side of high kVA rating transformers

B. Current transformers

C. High voltage side of high kVA rating transformers

D. High voltage side of low kVA rating transformers


16.During light loads, the transformer efficiency is low because

A. Secondary output is low

B. Transformer losses are high

C. Fixed loss is high in proportion to the output

D. Cu loss is small


17.The open circuit test is carried out in a transformer to find the

A. Cu loss

B. Core loss

C. Total loss

D. Insulation resistance


18.The equivalent resistance of the primary of the transformer having K = 5, R1 = 0.1 ohm when referred to secondary becomes …..ohm

A. 0.5

B. 0.02

C. 0.004

D. 2.5


19.A transformer has negative voltage regulation when its load power factor is

A. Zero

B. Unity

C. Leading

D. Lagging


20.A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be

A. 1600

B. 250

C. 400

D. 1250


21.The iron loss of the transformer is negligible during short circuit test because

A. The entire input is just sufficient to meet Cu losses only

B. Flux produced is a small fraction of the normal flux

C. Iron core becomes fully saturated

D. Supply frequency is held constant


22.In operating a 400hz transformer at 50Hz

A. Only voltage is reduced in the same proportion as the frequency

B. Only KVA rating is reduced in the same proportion as the frequency

C. Both voltage and KVA rating are reduced in the same proportion as frequency

D. None of these


23.When a 400Hz transformer is operated at 50Hz its KVA rating is

A. Reduced to 1/8

B. Increased 8 times

C. Unaffected

D. Increased 64 times


24.Which of the following does not change in a transformer

A. Current

B. Voltage

C. Frequency

D. All of these


25.In a transformer the resistance between its primary and secondary is

A. Zero

B. 1Ω

C. 1000 Ω

D. Infinite


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