Q7.25 (a) A small town with a demand of 800 kW of electric power at 220V is situated 15km away from an electric plant generating power at 440V. The resistance of the two wire line carrying power is 0.5\Omega  per km. The town gets power from the line through a 4000-220V step-down transformer at a sub-station in the town. Estimate the line power loss in the form of heat.

Answers (1)
P Pankaj Sanodiya

Power required 

P=800kW=800*10^3kW

The total resistance of the two-wire line

R=2*15*0.5=15\Omega

Input Voltage 

V_{input}=4000V

Output Voltage:

V_{output}=220V

RMS Current in the wireline

I=\frac{P}{V_{input}}=\frac{800*10^3}{4000}=200A

Now,

Power loss in the line 

P_{loss}=I^2R=200^2*15=600*10^3=600kW

Hence, power loss in line is 600kW.

 

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