Energy can not be stored, so moving electricity requires packing power as heavily as possible onto transmission lines. By increasing electricity’s voltage—an electromotive force that acts like water pressure—it moves more efficiently. Some energy gets lost along the way, but the bulk reaches its destination.
Substations serve as essential “transit” points in this system, with the ability to raise, or “step up,”, and lower, or “step down,” voltage. High voltage, you see, may be great for speeding power along transmission highways. However, if electricity enters your home at too high a level electronics could be damaged (case in point: lightning strikes).
As power gets closer to its destination, substations decrease it to a safe level. Substations also keep voltages constant, preventing harmful fluctuations.
Several types of substations are found between power plants and homes. Each contains a wide array of equipment, including transformers, lightning arrestors, circuit breakers, insulators, and more. A transformer performs the heavy work, altering voltage as needed.
Initially, step-up substations at power plants increase electricity’s voltage to various levels between (115,000 volts and 765,000 volts) so it can be shipped through high-voltage transmission lines. Once electricity gets closer to its destination, transmission substations typically reduce the voltage to between 23,000 volts and 69,000 volts.
From there, the power moves over smaller transmission facilities to electric co-op distribution systems. Distribution substation transformers then slash the voltage even lower, normally to 12,500 volts.
At this point, the distribution lines you see running up and down rural roads and across fields bring power to you. To make that energy safe for household use, a pole-mount transformer (the round object resembling a small gray garbage can located near the top of a utility outside your residence) or a pad-mount transformer (the gray boxes dotting your housing development) cuts the voltage once more, to between 120 and 240 volts.
Substations remain an important part of your electric cooperative’s system. Remember, the voltage entering and exiting substations far exceeds anything you’ll find at home. Substation fences protect you and the equipment housed within and help ensure that your co-op can continue providing you with a safe, reliable, and affordable supply of power.