1. A 50 km long transmission line supplies a load of 5 MVA at 0.8 p.f. lagging at 33kV. The efficiency oftransmission is 90%.
Calculate the volume of aluminium conductor required for the line when (i) single phase, 2-wire system is used (ii) 3-phase, 3-wire system is used. The specific resistance of aluminium is 2.85 x 10-8 Ω m.
2. A sub-station supplies power at 11 kV, 0.8 p.f lagging to a consumer through a single phase transmission line having total resistance (both go and return) of 0.15 Ω.
The voltage drop in the line is 15%. If the same power is to be supplied to the same consumer by two wire d.c. system by a new line having a total resistance of 0.05 Ω and if the allowable voltage drop is 25%, calculate the d.c. supply voltage.