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# 1.1 (3 marks) A single-phase power system consists of a 480 volt 60 Hz generator supplying...

1.1 (3 marks) A single-phase power system consists of a 480 volt 60 Hz generator supplying a load of 4 + j 3 ohms through a transmission line whose impedance is 0.18 + j 0.24 ohm. The generator impedance may be neglected.

1.1.1 Determine the transmission loss (power loss in the transmission line resistance. (1 mark)

1.1.2 Redo the 1.1.1 when the following is done to the power system. The generated voltage is stepped up ten times by using an ideal transformer of turns-ratio 1:10. At the load end the reverse is done i.e a step-down transformer with turns-ratio of 10:1 is used before connecting the load. (1 mark)

Redo 1.1.2 using per unit quantities. You may select 50 kVA and 480 volts as bases. (1 mark)

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Here, first with actual line and load impedances, line current is calculated. The losses in resistance of transmission line is calculated. After this by including transformers, impedances on one side is calculated. Then line current and losses in line resistance is calculated. At the end by using per unit system, line losses are calculated.

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