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Our electrical power system delivers electricity to our homes. The power plant generates electricity. Wires carry the power to homes and businesses. Along the way, transformers change the voltage of the electricity.
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Electric Power Delivery System

When you switch on a light in your house, you are using the electrical power system. A power plant generates the electricity. Electrical power travels along wires to your house. The light switch lets the electricity flow to the light bulb.

We use AC (alternating current) electricity in our homes and businesses. The electrons don't actually flow along the wires. Instead, they vibrate back and forth very quickly (60 times each second!). When you plug in an appliance, the outlet supplies power to move electrons that are already in the wiring of the appliance.

When electricity leaves a power plant, we use a device called a transformer to increase or "step up" the voltage. The high voltage electricity (more than 100,000 volts!) is then ready for the long trip over power lines to your neighborhood. High voltages are good to use when electricity will travel a long distance. Less energy is lost during the trip if we use high voltages.

Near your house, more transformers are used to change the voltage again. This time the transformers decrease or "step down" the voltage. We use 110 volt electricity in our homes. Lower voltages are better to use in our homes because lower voltage electricity is safer.

Space weather can mess up the electrical power system by damaging transformers. Space weather storms can cause direct current (DC) electricity to flow in wires. Transformers are made to work with AC power. DC power causes transformers to overheat or even catch on fire.

Last modified February 17, 2009 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA