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A 50Hz, 220kV, three phase, fully transposed transmission line is 60km long. The phase conductor's resistance, inductive reactance and shunt admittance are given as 0.150/km, 0.44/km and 4x10-S/km respectively. The transmission line supplies a three-phase load of 240MW with 0.8 lagging at 220kV. a) Apply the short line model by ignoring the shunt admittance to calculate: i) The sending end phase voltage and the percentage voltage regulation [4 marks) ii) The three-phase sending power and line efficiency. [3 marks) b) The transmission line is planned to be extended to 250km long using the same conductors material and size to supply the same load of 240MW at 220kV, with a leading power factor of 0.8. i) Draw the nominal PI circuit model highlighting all the circuit parameter values [4 marks] ii) Apply the PI model to calculate the ABCD parameters of the line [4 marks] iii) Determine the sending end phase voltage, current and three phase power [4 marks) iv) Calculate the percentage voltage regulation and line efficiency [4 marks) v) Suggest methods of improving the transmission line voltage regulation and efficiency. [2 marks] Total: 25 marks