Electrical Distribution: Understanding How the Power Grid Works

by Madhuri Boinwad

In 2020, the US utility-level electrical power grid generated and distributed. It’s a tremendous amount of energy — 11,432 kWh for every person in the U.S., in fact.

But how does electricity get from the coal, nuclear, wind, or solar power plants to your phone or computer? There’s a lot that comes between you and the power plant — and that’s a good thing!

Between residential solar, debates about eliminating fossil fuels, and integrating new nuclear power sources, there’s a lot of reasons to know how our energy grid works.

Keep reading to answer all your questions about how electricity gets from A to B to you!

Starting at the Energy Source: Generation and Transmission

No matter the type of generator, electricity is created as direct current (DC) at the source. It’s fed into a transformer which steps up the voltage to HV (high voltage) or UHV (ultra-high voltage) levels. It also transforms the current from DC to AC (alternating current).

The transmission system sends as high a voltage as possible because a higher voltage system is more efficient over long distances. AC is best for long distances because you can convert DC electricity into a higher AC voltage.

The problem with AC, though, is that it’s difficult for appliances and consumer electronics to work on it. The exception is when those appliances use large electric motors meant for AC electricity. However, DC electric motors are more common in the home, even on washing machines.

Industrial applications like a factory, paper mill, or recycling center may draw electricity directly from the AC transmission line. They’ll change it to DC in their own private substation, or feed it directly into some of their machines.

Substations Step Down the Power: Distribution

For primary customers, and secondary customers another transformation has to take place in the electrical system. These happen in substations.

They change the energy into DC power again for local electrical distribution. These transformations step the voltage back down to about 34kV to 132 kV.

From here on there are insulated wires and cables, transformers, circuit breakers, relays, fuses, control systems, and local power poles.

Because of the nature of the electrical system, fluctuations and surges mean you need to use a circuit breaker or fuse to help protect and regulate it. Lightning strikes are a common problem because transmission lines are so tall and electrically grounded.

The grid is becoming “smarter” every day with electrical sensors and components that help to direct and regulate the flow of electricity with redundant systems.

High voltage lines bring DC power to smaller factories and commercial buildings directly. Even large apartment buildings may get directly tied into this main distribution level.

For residential use, a final transformer takes the high voltage from the power lines. It brings the voltage even lower, to the 120V or 240V of your home. 

How the U.S. Power Grid Works

As you can see, the power grid relies on a system of transformers, circuit breakers, and fuses to keep things flowing. Though, transformers do the heavy lifting and get all the attention.

Want to know more about electricity and the tech that uses it? Keep browsing out articles for more!

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