Two balanced three-phase systems, X and Y, are interconnected with lines having impedance Z _{\text {line }}=1+j 2 \Omega . The line voltages are V _{a b}=12\underline{ / 0^{\circ}} kV \text { rms and } V _{A B}=12 \underline{/ 5^{\circ}} kV rms, as shown in Fig. 11.21a. We wish to determine which system is the source, which is the load, and the average power supplied by the source and absorbed by the load.