Problem 1: Consider the positive phase sequence balanced three-phase wye-wye circuit system shown below: n Van 1+ Vbn 1+ Ven 1+ Tan Vab | 50 ĪGA Zw Zw Zw A + VAB B g TAN Zy Zy Zy N The line and load impedances are 0.6 + j0.2 2 and 8+j12 2 per phase, respectively. The phase voltage at the load VAN = 365261° Vrms. Determine the line voltages at the source. Ans: Vab 654.304289.509° Vrms; Vbc = 654.3042-30.491° Vrms; Vca = 654.3042-150.491° Vrms

2. Three Unbalanced loads connected in wye configuration and is impressed by a balance three phase, four-wire source. The per phase voltage of the source is 230V. Assume phase voltage A as reference, determine the line currents Ia, Ib and Ic and the neutral current if the following unbalance loads are: Load an: 30kW at 0.8 lagging power factor Load bn: 50kW at 0.6 lagging power factor Load cn: 30 kW at 0.9 leading power factor.