Machine-translated by Google. Questions are authored in English.
Top

Discussion

A transformer with 2 kW of iron loss and 8 kW of copper loss at full load reaches maximum efficiency at

  • A.71 per cent of full load
  • B.50 per cent of full load
  • C.25 per cent of full load
  • D.100 per cent of full load

Answer: B

Correct answer: 50 per cent of full load

Maximum efficiency occurs where the variable loss equals the constant loss. With copper loss varying as the square of the loading \( x \), \[ 8x^2 = 2 \quad\Rightarrow\quad x^2 = 0.25 \quad\Rightarrow\quad x = 0.5. \] So this transformer is most efficient at half load, and in general \( x = \sqrt{P_{iron}/P_{copper}} \) - which is why distribution transformers are commonly sized to run well below their nameplate.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.