I have already done a), just need b and c. Answer key is here, please give solution that is in accordance to the answer key:

4. HW3 Q4 A three-phase 80 kVA transformer is rated to a primary voltage of 2.2 kV and a secondary voltage of 220 V. The transformer parameters are determined by open and short circuit tests. The results of the open and short circuit tests are: Short-circuit test (low-voltage side short-circuited; data measured at high-voltage side): Vse = 48 V Isc = 32 A Psc = 800 W Open-circuit test (high-voltage side open; data measured at low-voltage side) Voc = 220 V Loc = 5.7 A Poc = 220 W (a) Determine the parameters of the equivalent circuit. Draw the equivalent circuit of the transformer. (b) Plot the voltage regulation and efficiency versus the load for both lagging and leading power factors of 0.6, 0.8 and 0.9. Obtain the maximum efficiency values. Assume the load voltage is equal to the rated secondary voltage of the transformer. (c) Assuming the primary rated voltage is being supplied to the transformer, determine the load voltage when the transformer carries half load and the power factor is 0.8 both lagging and leading. 7.11. (a) R. = 0.26 12, X. = 0.83 12, R. = 220 12, Xm = 22.4 12; (b) No.6lag, max = 98.8%, no.Slag,max = 99.1%, 10.9lag,max = 99.2%, 70.6lead,max = 98.9%, 90.8lead,max = 99.2%, No.9lead,max = 99.3%; (c) Vlag = 219 V, Vlead = 221 V