A 15-kVA, 8000/230-V distribution transformer has an impedance referred to the primary of 80+j300 ohm. The components of the excitation branch referred to the primary side are Rc= 350k ohm and Xm=70k ohm.
If the output voltage is 230 V and the load impedance is ZL=3.2+ j1.5 ohm, what is the efficiency of the transformer?