A 40-km, 220-kV, 60-Hz three-phase overhead transmission line has a per-phase resistance of 0.15 Ω/km, a per-phase inductance of 1.3263 mH/km, and negligible shunt capacitance.
Using the short line model, find the sending-end voltage, voltage regulation, sending-end power, and transmission line effciency when the line is supplying a three-phase load of:
(a) 381 MVA at 0.8 power factor lagging and at 220 kV,
(b) 381 MVA at 0.8 power factor leading and at 220 kV.