Question 1 of 35

1. What activates the top float switch in a Buchholz relay?

High temperature condition

Overloading condition

Moisture presence

Open circuit condition

Question 1 of 35

Question 2 of 35

2. Why are laminated cores used in transformers?

Reduce mechanical loss

Reduce copper loss

Reduce hysteresis loss

Reduce eddy current loss

Question 2 of 35

Question 3 of 35

3. What condition gives maximum transformer efficiency?

Copper loss < Iron loss

Copper loss = Eddy current loss

Copper loss = Iron loss

Copper loss > Iron loss

Question 3 of 35

Question 4 of 35

4. What type of transformer is this?

Audio frequency transformer

Auto transformer

Core type transformer

Shell type transformer

Question 4 of 35

Question 5 of 35

5. Which construction technique reduces copper loss in large transformers?

Laminated core

Grain oriented core

Stepped core arrangement

Reduced core thickness

Question 5 of 35

Question 6 of 35

6. What is this power transformer component called?

Buchholz relay

Tap charger

Breather

Explosion vent

Question 6 of 35

Question 7 of 35

7. What does the crackle test of transformer oil determine?

Viscosity

Moisture

Dielectric strength

Acidity

Question 7 of 35

Question 8 of 35

8. What is the relationship between primary voltage (E₁ V₁ ) and secondary voltage (E₂, V₂) in an ideal transformer?

E₁ > V₁ and E₂ > V₂

E₁= V₁ and E₂ = V₂

E₁ = V₁ and E₂ = V₂

E₁ < V₁ and E₂ < V₂

Question 8 of 35

Question 9 of 35

9. What is the function of a conservator in a transformer?

Prevents moisture entry

Transfers heat to atmosphere

Releases internal pressure

Allows oil expansion due to load variation

Question 9 of 35

Question 10 of 35

10. Why is load disconnected before OFF-load tap changing?

Avoid heavy sparking at contacts

Provide electrical isolation for windings

Disconnect diverter moving contact

Disconnect tappings from neutral

Question 10 of 35

Question 11 of 35

11. Which transformer measures high voltage installations?

Potential transformers

Ignition transformers

Pulse transformers

Constant voltage transformers

Question 11 of 35

Question 12 of 35

12. What is the composition of silicon steel in transformer cores?

93% steel, 7% silicon

95% steel, 5% silicon

97% steel, 3% silicon

90% steel, 10% silicon

Question 12 of 35

Question 13 of 35

13. How is copper loss determined in transformers?

Ratio test

Open circuit test

Short circuit test

Impulse test

Question 13 of 35

Question 14 of 35

14. Which transformer loss is determined by short circuit test?

Eddy current loss

Windage loss

Hysteresis loss

Copper loss

Question 14 of 35

Question 15 of 35

15. Calculate the voltage regulation percentage if no-load voltage is 240V and full-load voltage is 220V:

8.30%

8.71%

7.20%

9.09%

Question 15 of 35

Question 16 of 35

16. What type of EMF is induced in an ideal two-winding transformer?

Dynamically induced EMF

Mutually induced EMF

Self induced EMF

Statically induced EMF

Question 16 of 35

Question 17 of 35

17. Which cooling method is used in pole-mounted distribution transformers?

Oil forced air forced

Oil natural air blast

Oil natural air natural

Air natural

Question 17 of 35

Question 18 of 35

18. What is the purpose of tap changing in power transformers?

Maintain secondary voltage

Change distribution voltage ratio

Optimize for maximum efficiency

Maintain primary voltage

Question 18 of 35

Question 19 of 35

19. How is moisture controlled in transformer breathers?

Sodium chloride

Transformer oil

Ammonium jelly

Silica gel

Question 19 of 35

Question 20 of 35

20. Why are ferrite cores used in radio receivers?

Reduce electric interference

Increase receiver efficiency

Reduce constant losses

Improve sound quality

Question 20 of 35

Question 21 of 35

21. Which type of transformer is used for high frequency applications?

Ring core transformer

Ferrite core transformer

Grain oriented core transformer

Silicon steel core transformer

Question 21 of 35

Question 22 of 35

22. Why are distribution transformers typically delta-primary and star-secondary?

Maintain constant voltage

Facilitate 3-phase 4-wire distribution

Avoid overloading

Reduce transformer losses

Question 22 of 35

Question 23 of 35

23. What is the function of Buchholz relay in power transformers?

Protection from high temperature

Protection from moisture in oil

Protection from tank pressure

Protection from overloading and short circuits

Question 23 of 35

Question 24 of 35

24. How can potential transformer reading errors be reduced?

Using thin laminated core

Using high flux density material

Providing long magnetic path

Using good quality core material

Question 24 of 35

Question 25 of 35

25. What is the advantage of stepped core in large transformers?

Reduces hysteresis loss

Reduces core space

Minimizes copper use

Reduces eddy current loss

Question 25 of 35

Question 26 of 35

26. Why does a current transformer core have low reactance and low core losses?

To minimize reading errors

To minimize the burden

To prevent high static shield

To maintain constant output

Question 26 of 35

Question 27 of 35

27. What is the purpose of an explosion vent in power transformers?

Heat releasing

Moisture releasing

Air releasing

Pressure releasing

Question 27 of 35

Question 28 of 35

28. What material is used in breathers to prevent moisture in transformer oil?

Silica gel

Sodium chloride

Charcoal-salt mixture

Ammonium chloride

Question 28 of 35

Question 29 of 35

29. What is the cooling method of transformers?

Oil natural air forced cooling

Oil forced air forced cooling

Oil natural cooling

Oil natural water forced cooling

Question 29 of 35

Question 30 of 35

30. What is absolutely essential for parallel transformer operation?

Insulation class

Nature of load

Phase sequence

Type of cooling

Question 30 of 35

Question 31 of 35

31. Which material is used to make the core of power transformers?

Soft iron

Cold rolled grain oriented steel

Copper alloy

Rolled steel

Question 31 of 35

Question 32 of 35

32. What type of transformer is this?

Iron core transformer

Air core transformer

Ring core transformer

Ferrite core transformer

Question 32 of 35

Question 33 of 35

33. Why is the primary of a potential transformer wound with thin wire and many turns?

To regulate primary current

To offer high inductance

To obtain required voltage ratio

To stabilize input/output voltage

Question 33 of 35

Question 34 of 35

34. Which loss is assessed by open-circuit test?

Hysteresis loss only

Copper loss

Core loss

Eddy current loss only

Question 34 of 35

Question 35 of 35

35. What is the disadvantage of auto transformers?

More losses

Heavier weight

Poor voltage regulation

Cannot isolate secondary winding

Question 35 of 35