Question

5. A three-phase line, which has an impedance of (2 + j4) Ω per phase, feeds two balanced three-phase loads that are connected in parallel. One of the loads is Y- connected with an impedance of (30 + j40) Ω per phase, and the other is delta- connected with an impedance of (60 + j45) Ω per phase. The line is energized at the sending end from a 60-Hz, three phase, balanced voltage source of 120√3 V (rms, line- to-line). Determine (a) the current, real power, and reactive power delivered by the sending-end source; (b) the line-to-line voltage at the load; (c) the current per phase in each load; and (d) the total three-phase real and reactive powers absorbed by each load and by the line. Check that the total three phase complex power delivered by the source equals the total three-phase power absorbed by the line and loads. *Tip: Draw a per- phase equivalent circuit and then find a total impedance viewed from the input terminals.