- #1
titaniumpen
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Homework Statement
65 kW is to arrive at a town over two 0.100 ohm lines. Estimate how much power is saved if the voltage is stepped up from 120 V to 1200 V and then down again, rather than simply transmitting at 120V.
2. The attempt at a solution
First I want to find the power lost in each line. Since the power is delivered over two lines, the power over each line is half of the total.
P = VI
65000/2 = 120I
I = 271 A
So for the total power lost in the two lines,
P = (I^2)*R*2
P = 14670 W
Now I want to find the power lost if the voltage is 1200V. The same procedures apply.
65*10^3/2 = 1200I
I = 27.1 A
P = (I^2)R*2
P = 146.7 W
Difference between the two values of "wasted" power = 14500 W
That's my answer. But the textbook gave me an answer of around 54000 W. I looked at its steps. I don't know if they are wrong. The book first finds the delivered current by the equation 65000 W = 120 I
Then it finds the power wasted by the 2(I^2)R. Is that double counting?