Question

In: Physics

A small city requires about 10 MW of power. Suppose that instead of using high-voltage lines...

A small city requires about 10 MW of power. Suppose that instead of using high-voltage lines to supply the power, the power is delivered at 120 V.

Assuming a two-wire line of 0.48?cm -diameter copper wire, estimate the cost of the energy lost to heat per hour per meter. Assume the cost of electricity is about 10 cents per kWh.

Solutions

Expert Solution

Given that
          P = 10MW
            = 10*106W
         V = 120V
We know the formula of the power is P = VI
                                                        I = P / V
Now power loss is
                                        
                                       
                               ...........................(1)
Here P = 10*106W
        V = 120V
        ? =1.68*10-8?.m
        ? = 3.14
        d =0.48*10-2m

Putting the values in formula (1), we get

P/L = 12.9 MW/m

Cost of energy lost = 12900*.10 $/hr m = 129 $/hr m


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