Electric utilities in the U.S. and elsewhere are working with composite suppliers to take advantage of fiberglass composite as a replacement for wood and metals in power transmission towers, distribution poles and cross-arms, as well as the strength members in the aluminum conductor cables they support. Pultruded and filament wound composite utility poles and cross-arms are overcoming buyer resistance as electric power companies employ them primarily as replacements for aging wood poles in remote and/or extremely humid locations.
In composite-reinforced aluminum conductor (CRAC) cables, the traditional steel strength members are replaced with a pultruded continuous-fiber core, which is expected to reduce weight and increase power-transmission efficiency by 200 percent. Because CRAC cabling weighs less than steel-cored cable, it is expected to be an attractive alternative for upgrading power lines. An increased number of cables can be hung from each existing tower, increasing power transmission capability without the huge expense of erecting new towers or obtaining additional rights of way.
The 3M co. (St. Paul, Minn.) is in the process of doubling its capacity to produce its high-capacity electricity transmission conductor, 3M ACCR (aluminum conductor composite reinforced), in late 2012 at its plant in Menomonie, Wis. The production line expansion is in response to accelerating growth in product demand from utilities in the U.S. and abroad. To date, the conductor is in use in 11 nations on four continents. The 3M ACCR product is a lightweight, low-sag overhead conductor that can increase transmission capacity by up to 100 percent or more, compared to conventional steel core conductors of the same size. It has been selected where construction is challenging or uneconomical, including environmentally sensitive areas, crowded urban neighborhoods and wherever line clearance is an issue, without requiring new tower construction.