placement online test 2 (Transformers)

1. Which of the following losses in a transformer is constant under all load conditions?

• a) Copper loss

• b) Core loss

• c) Stray loss

• d) Eddy current loss

Answer explanation

b) Core loss → Core (iron) losses depend only on voltage and frequency, remaining constant under all load conditions.

2. What will happen if a DC supply is applied to a transformer?

• a) It will work normally

• b) It will produce excessive heat and damage the transformer

• c) It will step up the voltage

• d) It will improve efficiency

Answer explanation

b) It will produce excessive heat and damage the transformer → A transformer relies on electromagnetic induction, which requires AC. DC causes saturation and overheating.

3. Which of the following connections is commonly used for large power transformers?

• a) Star-Star

• b) Delta-Delta

• c) Delta-Star

• d) Open-delta

Answer explanation

c) Delta-Star → Delta-Star connection is commonly used in power distribution transformers to step down voltage and provide a neutral point.

4. The primary purpose of using a tap changer in a transformer is to:

• a) Increase efficiency

• b) Control the output voltage

• c) Reduce losses

• d) Improve insulation

Answer explanation

b) Control the output voltage → Tap changers adjust the number of active turns in the winding to regulate voltage under varying load conditions.

5. What is the main function of transformer conservator?

• a) Store extra transformer oil

• b) Provide cooling

• c) Filter out impurities in oil

• d) Protect the transformer from overvoltage

Answer explanation

a) Store extra transformer oil → The conservator tank accommodates the expansion and contraction of oil due to temperature variations.