T&D World Magazine

Major Utility in Southern U.S. Upgrades Transmission Lines with 3M ACCR to Avoid Wetlands Tower Construction

Georgia Power, a subsidiary of Southern Company, has chosen the lightweight, low-sag 3M ACCR overhead conductor to double transmission capacity on a set of lines that cross extensive wetlands near Savannah. The upgrade significantly reduces the need for larger towers or a wider right of way, thus avoiding a range of potential challenges, including construction on environmentally sensitive land.

Based in Atlanta, Southern Company serves more than 4.4 million residential, commercial and industrial customers in four states. Georgia Power is its largest subsidiary.

The upgrade is on a 16.7-mi line linking the Kraft generating plant in Savannah with its McIntosh plant north of the city. The project resolves potential capacity issues by approximately doubling the 230-kV double circuits’ line capacity, replacing a conventional steel core conductor with a 3M ACCR 1622 kcmil conductor that is light enough to be accommodated mostly by the existing infrastructure.

After studying a number of options and considering the capacity increases achievable; the costs of structures, construction and permitting, and conductor costs, Georgia Power chose ACCR as the most cost-effective option.

Bob Beck, Southern Company Services Senior Transmission Planner, cited three issues that confronted the upgrade project: right-of-way expansion was not feasible, wet terrain made tower construction very expensive and environmentally problematic, and construction outages were limited to light-load periods.

“3M ACCR enabled us to use mostly existing towers and to re-conductor with minimal disturbance to the land and no service interruption,” he said.

In 2013, the company is completing a similar project with 3M ACCR to further enhance area reliability.

3M ACCR’s composite core is as strong as steel, but lighter, and its coefficient of thermal expansion is half that of steel.

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