A small town with a demand of 800 kW of power at 220 V is situated 15 km away from an electric plant generating power at 440 V. The resistance of the two wire line carrying power is `0.5Omega`.`km^-1`. The line gets power from the line through a 4000-220 V step-down transformer at a substation in the town.
Characterise the step-up transformer at the plant.

Explanation

Generating power of Electric plant = 800
kW at V = 220 V
Distance = 15 km,
Generating voltage = 440 V
Resistance/length `= 0.5 Omega//km`
Primary voltage VP = 4000 V
Secondary voltage Vs = 220 V
Voltage drop across the line
`= I_(P).R`
`= 200xx0.5xx15xx2`
`= 3000 V`
Voltage from transmission
`= 3000+4000=7000 V`
As it is given that the power generated at 440 V
So, the step-up transformer needed at the plant is 440V - 7000 V.