Electric Transmission
Lines
Electricity: From Power Plants to Consumers
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Nature of electricity
Electricity is generated as it is used. Unlike other commodities, there is very little ability to store
electricity. Because of the instantaneous nature of the electric system, constant modifications must
be made to assure that the generation of power matches the consumption of power. The electric
system we’ve grown to depend on is very complex and dynamic, ever adjusting to meet changing
needs.
The amount of power on a line at any given moment depends on generation production and
dispatch, customer use, the status of other transmission lines and their associated equipment, and
even the weather. The transmission system must accommodate changing electricity supply and
demand conditions, unexpected outages, planned shutdowns of generators or transmission
equipment for maintenance, weather extremes, fuel shortages, and other challenges.
The transmission grid
The electrical transmission system is more complex and dynamic than other utility systems, such as
water or natural gas. Electricity flows from power plants, through transformers and transmission
lines, to substations, distribution lines, and then finally to the electricity consumer (Figure 1). The
electric system is highly interconnected.
The interconnectedness of the system means that the transmission grid functions as one entity.
Power entering the system flows along all available paths, not just from Point A to Point B. The
system does not recognize divisions between service areas, counties, states, or even countries.
The current transmission grid includes not only transmission lines that run from power plants to
load centers, but also from transmission line to transmission line, providing a redundant system that
helps assure the smooth flow of power. If a transmission line is taken out of service in one part of
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the power grid, the power can usually be rerouted through other power lines to continue deliver