Electric current from a power plant is "stepped
up" to high voltage (as high as 765,000 volts) by large transformers, so
it can be shipped long distances, through high-voltage transmission lines.
High-voltage electricity is either transferred to
a national grid of transmission lines to be exchanged with other utilities,
or "stepped down" to less than 39,000 volts at a distribution substation,
so it can be delivered safely through neighborhood distribution lines, to a
town near you.