A 3-phase ring main ABCD fed at A at 11 kV supplies balanced loads of 50 A at 0.8 p.f. lagging at B, 120 A at unity p.f. at C and 70 A at 0.866 lagging at D, the load currents being referred to the supply voltage at A. The impedances of the various sections are :
Section AB = (1 + j 0.6) Ω ; Section BC = (1.2 + j 0.9) Ω
Section CD = (0.8 + j 0.5) Ω ; Section DA = (3 + j 2)Ω
Calculate the currents in various sections and station bus-bar voltages at B, C and D.