(a) Figure Q1.1 illustrates a three-phase power system, in which an ideal three-phase ac generator with an abc phase sequence is connected through a three-phase transmission line to an unbalanced Δ-connected load. The generator is producing a line voltage of 940 V and the line impedance is .
(i) Calculate the line currents.
(ii) Find the real, reactive and apparent powers supplied by the generator.
(iii) Determine the overall power factor of the system.
(b) In Figure Q1.2, a three-phase four-wire system operating with a line voltage of 480 V is supplying a balanced motor load at 560 kVA and 0.86 power factor (pf) lagging. The motor load is connected to the three main lines marked a, b, and c. In addition, incandescent lamps (with unity pf) are connected as follows: 48 kW from line a to the neutral, 25 kW from line b to the neutral, and 14 kW from line c to the neutral. The three-wattmeter method is used to measure the power absorbed by the load in each line.
(i) Calculate the wattmeter readings.
(ii) Find the current in the neutral line.