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Since electricity is not easily stored, it is produced at nearly the instant it is used. To reach us, electrons produced at power plants and other generators travel at nearly the speed of light along a network of electric transmission power lines. The network, called the grid, refers to the high-voltage power lines that carry power over long distances and effectively connect generation points to electric distribution utilities and large industrial users. Distribution utilities then deliver power to homes, businesses and other customers over separate networks of smaller distribution power lines. The trip from power plant to outlet happens at almost 186,000 miles per second.
The electric business is divided into generation, transmission and distribution. While that’s simple enough, the picture gets complicated when you consider that Georgia’s transmission system is actually part of one interconnected grid that covers the Midwest, the entire Eastern Seaboard and parts of Canada. In addition, the amount of power being produced at dozens of locations in the state must meet the ever-changing demand occurring at literally millions of customer locations. Not only does generation have to be adequate, the transmission system in all regions of the state also must have sufficient capacity to meet demand, especially during our hottest summer days when peak demand occurs.
Power flows across the transmission system though a relay of different size power lines. In Georgia, 500-kilovolt (kV) lines, our largest, start the relay at power plants where substations increase, or step up, the voltage. Electric current travels over 500-kV lines to substations that step down the voltage and transfer it to 230-kV lines. The power then can be taken off by an EMC or industrial customer, or it can continue to lines of 115-kV lines, 69-kV or 46-kV. See the path of electricity slide show. The path taken by power is not dedicated. Instead, power flows throughout the grid, following the paths – available power lines – of least resistance. This helps to explain why power can stay on in an area even if a nearby power line or substations fails or is taken out of service. The electric demand, called load, is simply transferred to other lines in the area, assuming they have sufficient capacity. Like traffic, power simply travels around the trouble spot by using other routes.
It’s important to remember that the risk of outages and blackouts has a lot to do with there being sufficient capacity – generation and transmission – to meet the demand. That’s why utilities in Georgia and other fast-growing states emphasize planning and construction. Our work today determines the reliability of system years from now.
Check out the links to free children's education websites on our power line safety page.