The purpose to try to offset that pesky ol' resistance.
Wikipedia, the free encyclopedia - Electric power transmission
"It is necessary to transmit the electricity at high voltage to reduce the
fraction of energy lost. For a given amount of power transmitted, a higher
voltage reduces the current and thus the resistive losses in the conductor.
Long distance transmission is typically done with overhead lines at voltages
of 110 to 1200 kV."
The following is some text from a University of Virginia "slide show" on the
topic, and which charts the process.
= Power delivered to a city is:
power delivered = current · voltage drop
= Power wasted in transmission wires is:
power wasted = resistance · current2
= For efficient power transmission:
? Use low-resistance wires (thick, short copper)
? Use low current and high voltage drop
If you need any clarification, please feel free to ask.
Google search on: electricity transmission "high voltage"
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