Why do power companies use low currents in power lines whentransferring electric

Question

Why do power companies use low currents in power lines whentransferring electrical energy over large distances?

1 Because power lines have resistance andresistors transform electrical energy into heat. The lower thecurrent the lower the resistance of the power lines and hence theless electrical energy is lost to heat. Because powerlines have resistance and resistors transform electrical energyinto heat. The lower the current, the less heat generated (andhence the less electrical energylost).     Because powerlines have resistance and resistors transform electrical energyinto thermal energy. High currents would require larger power linesto reduce the amount of heat loss and hence be much more expensivethan the small power lines that low currents require.Because power lines have resistance andresistors transform electrical energy into thermal energy.According to Ohm's Law, the lower the current the lower thevoltage. Thus both the voltage & current will be low and hencethe power loss will be small. 1 Because power lines have resistance andresistors transform electrical energy into heat. The lower thecurrent the lower the resistance of the power lines and hence theless electrical energy is lost to heat. Because powerlines have resistance and resistors transform electrical energyinto heat. The lower the current, the less heat generated (andhence the less electrical energylost).     Because powerlines have resistance and resistors transform electrical energyinto thermal energy. High currents would require larger power linesto reduce the amount of heat loss and hence be much more expensivethan the small power lines that low currents require.Because power lines have resistance andresistors transform electrical energy into thermal energy.According to Ohm's Law, the lower the current the lower thevoltage. Thus both the voltage & current will be low and hencethe power loss will be small. 1 Because power lines have resistance andresistors transform electrical energy into heat. The lower thecurrent the lower the resistance of the power lines and hence theless electrical energy is lost to heat. Because powerlines have resistance and resistors transform electrical energyinto heat. The lower the current, the less heat generated (andhence the less electrical energylost).     Because powerlines have resistance and resistors transform electrical energyinto thermal energy. High currents would require larger power linesto reduce the amount of heat loss and hence be much more expensivethan the small power lines that low currents require.Because power lines have resistance andresistors transform electrical energy into thermal energy.According to Ohm's Law, the lower the current the lower thevoltage. Thus both the voltage & current will be low and hencethe power loss will be small. 1

Explanation / Answer

The primary aim in designing an efficient electricaldistribution system is to deliver the maximum possible wattage tothe load at the far end of the transmission line from thegenerating system. But wattage is lost as heat in the linesdelivering current to the load. Since power, in watts, W =V2*R, consider the voltages in the system:VTot is the voltage over the entire system, which is setby the generators, and VTot = Vline +Vload , since the system is a series circuit with lineand load resistances. Therefore, Vload =VTot - Vline. To maximize the voltageacross the load, one must minimize the voltage drop across theline. Since Vline = I*Rline, minimizing Iminimizes the voltage drop across the line, for a given lineresistance, Rline. By maximizing the load voltage,the power delivered to the load is also maximized.

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