Lightning arrestors

A lightning rod (left) and lightning arrestor (below) in a substation.

A lightning rod (left) and lightning arrestor (below) in a substation.

Lightning arrestors with a grounding wire between them on a distribution pole.

Lightning arrestors with a grounding wire between them on a distribution pole.

Summer storms have the potential to wreak havoc on power lines and substations with lightning contact. By using a protective device called a lightning arrestor, that potential is minimized.

A lightning arrestor provides a path to ground for over-voltages caused by lightning and other power surges to protect equipment and help prevent outages. This helps prevent or minimize damage to the power lines and equipment, and helps prevent power outages.

At substations, Dawson PPD uses lightning arrestors, lightning rods and static wire to protect equipment against voltage surges from lightning strikes either within the substation or on power lines connected to the substation.

A lightning arrestor acts as a conductor, allowing the voltage surge to flow to the ground. That keeps the substation equipment within design limits and protects the equipment from damage. When voltage returns to normal, the arrestor stops conducting.

A static or shield wire is uninsulated and not energized. It is hung at the highest point within a substation for lightning to strike it instead of the equipment below. The voltage from the lightning travels down the static wire and into the ground where it dissipates. These wires are also hung on sub-transmission lines.

A lightning rod works the same for a substation as it does on homes, barns and other tall structures. The rod is set as the highest point of a structure to attract the lightning. It is connected to a grounding wire to provide a path for electricity to take to the ground. In substations, the grounding system is a grid of wire underneath the equipment to help the voltage dissipate more quickly.

In general, lightning arrestors are installed at each incoming or outgoing transmission and distribution line within a substation and at each transformer.

On distribution lines, Dawson PPD places lightning arrestors on every pole with equipment, like transformers, or generally every four poles or quarter mile.

 

June 2018

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