Cooperative News

Anatomy of a substation

Learn about the equipment that helps bring reliable power to your home

Have you ever noticed the fenced or walled yards housing large electric equipment and wondered what they do? These substations are a crucial part of the power grid, taking electricity transmitted from the power plant and converting it to the power that serves your home and community.

Below, you’ll learn about the main components of a substation and the important role they play in bringing you power. Want to learn more? See how our substation crews keep the lights on without causing you any disruption.

Transmission lines

Transmission structures include the large lines that carry high voltage (69- or 138-kilovolts) electricity from the power plant to the substations. PEC owns 304 miles of transmission line. Across the entire grid, there are thousands more that help bring power to our substations.


These breakers protect important substation equipment from issues that occur on the power lines. Similar to the breakers in your home, they automatically “open” when there is a problem like a surge or short, breaking the circuit and preventing damage to equipment.


The transformer represents the core purpose of the substation. It reduces transmission voltage (69- or 138-kilovolts) to distribution voltage (7,200- or 14,400-volts) electricity. This lower voltage power can then be carried to members through PEC’s distribution lines.

Distribution lines

These power lines — like the ones you may see in your neighborhood — carry 7,200- or 14,400-volt power to members’ homes and businesses where a smaller transformer will step the voltage down once more before consumption. PEC operates 22,813 miles of distribution line across our 8,100 square mile service area.

Control house

This building houses carefully programmed, maintained, and monitored devices called relays that act as the brains of the substation, constantly monitoring and protecting the system. Relays can sense a problem — in the substation or out on the lines — and instruct the relevant breaker to open in a fraction of a second, protecting equipment and isolating the fault so a minimal number of members are affected.