Transformers MCQ - Multiple Choices Questions and Answers

Transformers MCQ is contains huge collections of multiple choices questions about Transformers, Types of transformers, Emf Equation, Transformation Ratios, Copper and Iron losses , Equivalent circuits on load and no load, Parallel operation, Voltage Regulation, Testing and maintenance of transformers, Auto transformers and special types transformers

The silicon steel preferably used in transformer core. Because it has ___________

Reduces hysteresis losses

Reduced the eddy current losses

Increases eddy current losses

less brittleness

The transformer core ins laminated . It is because _____________

reduce eddy current losses

reduce hysteresis losses

reduce wight of the transformer

Effective cooling of transformer

The thickness of a transformer core is t mm. The hysteresis losses occurs in transformer is proportional to

$r^2$

$r^{1.6}$

None of above

The voltage ratio of the transformer in between primary and secondary winding given by

$V_s/V_p$

$V_p/V_s$

$V^s/V^p$

$V^p/V^s$

The number of turns in a secondary side of the transformer is 38. The rating of the transformer is 3300/250V 50 HZ. Find the number of turns in secondary side

239

257

125

250

The number of turns in a secondary side of the transformer is 38. The rating of the transformer is 3300/250V 50 HZ.Find the emf induced per turn

16.2

6.5

8.2

A transformer connected with a input supply and operating at no load condition. The losses occurring inside the transformer are __________

Eddy current losses

Hysteresis losses

Iron losses

copper losses

A single phase transformer is having core thickness of t mm and magnetic flux density B. How eddy current losses are depends on these parameters?

$Bt^2$

$B^2t^2$

$B^2t$

$B^{1.6}t^2$

Which is the following transformer is always connected with load throughout day

Power transformer

Distribution transformer

Current transformer

Booster transformer

10.

The general working principle of a transformer is

Mutual induction

Self Induction

Chemical reaction

Thermal reaction

1 out of 5

11.

The shell type transformer used in single phase will be ___________ number of cores

12.

There are 4000 turns per phase in the HV winding of a particular transformer, then number of turns per phase in the same winding for 2.5% tapping

4100

3902

4400

4000

13.

There are 4000 turns per phase in the HV winding of a particular transformer, then number of turns per phase in the same winding for 5% tapping

4200

4000

4210

4850

14.

Tertiary winding in a transformer usually connected as

Star connection

Delta connection

T connection

Series connection

15.

A single phase transformer has primary and secondary turns are 250 and 1000 respectively. If transformer connected with 230V primary voltage, what will be the secondary voltage induced in it?

920

330

1840

860

16.

In a transformer number of primary turns are reduced to 50% and same time input applied voltage increased to 200%. Then emf induced in secondary side _______________ compared with primary

0.50

Remains same

Doubles

One fourth

17.

The iron losses are measured in a transformer when it operating at no load condition is 500 W. When it connected to the full load, calculate the iron losses occurring?

200 W

180W

500W

600W

18.

When a transformer is operating at maximum efficiency, It is looses is 3500 KW. What will be the copper losses

2000 W

1000 W

1750 W

2750 W

19.

The thickness of the transformer core in generally

0.05 mm

0.2 mm

0.35 mm

1 mm

20.

The magnetic circuit of a transformer known as ______________

Core

Yoke

Core and Yokes

Cooling coils

2 out of 5

21.

The copper losses of a transformer is 1600 W. If load reduced by 0.5% of its full load. Find the copper losses

1600 W

1200 W

400 W

800W

22.

The breather in the oil cooled transmformer , filled with ______________

Oil

Calcium chloride

Water

Liquid

23.

The porceleain insulators are used in transformer bushing used in __________ grade of transformer

3.3 KV

11 KV

33 KV

66 KV

24.

A 20 KVA 2200/220V ,50 HZ single phase transformer primary winding reduced by 0.8 ohm. The resistnace of primary related to secondary

0.8 Ohm

8 Ohm

80 Ohm

0.008 Ohm

25.

When comparing with hot rolled steel, losses in cold rolled steels are reduced by ______________

80%

30%

50%

75%

26.

A distibution transformer operating under leading power factor condition. Select the correct relation between No load voltage ( E ) and full load voltage (V)

E=V

E>V

E<V

None of these

27.

Find the current flowing thorugh secondary winding of transformer has rating 25KVA,6600/440V. Consider that transformer is operating under full load condition

18.96 Ampere

32.8 Ampere

10.9 Ampere

56.74 Ampere

28.

Find the current flowing thorugh primary winding of transformer has rating 25KVA,6600/440V. Consider that transformer is operating under full load condition

1.26 Ampere

3.78 Ampere

2.18 Ampere

0.73 Ampere

29.

The voltage regulation of the transformer is operating is operating at leading power factor

30%

-5%

30.

The purpose of breather used in a transformer __________________

Reduce over loading

maintain balanced condition

Extract moisture from air

Storage of excess oil

3 out of 5

31.

The reactance and resistance corresponding to the line losses component is 300 Ohm and 600 Ohm respectively. The rating of transformer is 200/400. Find the no load current

0.67 - j0.33 A

0.33 -j0.36 A

0.33-j0.67 A

1.2 - j0.33 A

32.

If the primary exciting current vary by sinusoidal, the flux generated by the transformer also ____________

Sinusoidal

Square

Rectangular

Saw tooth

33.

If the Emf induced winding is flat topped, the core losses will be

Increases

decreased

Remains same

None of these

34.

A 1000 KVA 11000/440 V 3 ph. 50Hz transformer is operating at no load condition. Find the voltage across secondary terminal

440

11000

1000

220

35.

A 1000 KVA 11000/440 V 3 ph. 50Hz transformer is operating at no load condition. Find the current flowing through the secondary winding if power factor is 0.8

609

709

1218

1418

36.

1.5 T

< 1.5 T

> 1.5 T

37.

The flux linkages between primary and secondary winding of transformer is 0.06 wb. The cross sectional area of the core is 400 Sq.cm. Find the flux density

1.5 T

< 1.5 T

> 1.5 T

38.

The total losses occurring in a transformer rating 3KVA is operating at full load is about

300 W

30 W

180 W

60 W

39.

The transformer is generally rated in _________

KVA

Henry

40.

A 1000 KVA 11000/440 V 3 ph. 50Hz transformer is operating at no load condition. Find the terminal voltage across the secondary winding

400

440

11000

1000

4 out of 5

41.

The maximum efficiency of a transformer can be achieved under ________ full load condition

100%

80%

125%

50%

42.

If the B is maximum flux density of the core of a transformer, Hysteresis losses is proportional to

$B^{2.4}$

$B^{1.6}$

$B^{1.4}$

43.

In high voltage transformers , saving the insulation, star connection is compared to delta is about _____

10%

44.

The transformer will operate at maximum efficiency, when the following condition is satisfied

Hysteresis losses = Eddy current losses

Iron losses = Copper losses

Hysteresis losses = copper losses

None of above

45.

99.3

89.9

46.

The transformer has two winding i.e. primary and secondary on same core. The iron losses will occur on

Core only

Yokes Only

Core and Yokes only

In both coils

47.

1800

2100

2200

200

48.

The power factor of a transformer is always

Lagging

Leading

0.9 lagging

Depends on nature of connected with it

49.

In small capacity of transformer shape of winding conductors are used in both primary and secondary windings are

LV: Round, HV-Rectangular

Both HV and LV are round

Both HV and LV are rectangular

LV: Rectangular, HV: Round

50.

When Emf induced in transformer winding is peak. Eddy current losses of the same transformer will be ____________

Decreased

Remains same

Increased

None of these

5 out of 5

Transformers MCQ – Multiple Choices Questions and Answers

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