A transformer has constant iron loss 400 W and full-load copper loss 900 W. Secondary voltage is approximately constant with load. Which statements are correct?

Select all that apply

• Option A

  Maximum efficiency occurs at two-thirds of full-load current.

• Option B

  At maximum efficiency copper loss is 400 W.

• Option C

  At maximum efficiency total internal loss is 800 W.

• Option D

  Maximum efficiency occurs when copper loss equals iron loss.