Q. A 10-kVA transformer is known to have an iron loss of 150 W and a full-load copper loss of 250 W. If the transformer has the following load cycle, compute its all-day efficiency:
4 hours full load at 0.8 power factor
8 hours 75% full load at 1.0 power factor
12 hours 50% full load at 0.6 power factor