Washington state utility chooses 3M for transmission line upgrades

St. Paul, Minn., May 21, 2010 — Grays Harbor Public Utility District will become the first electric utility in Washington State to deploy the new 3M Aluminum Conductor Composite Reinforced this summer, as part of a general upgrade of its transmission lines.

The light-weight, low-sag conductor provides high transmission capacity without requiring larger towers or rights of way. It will be applied on a 1,676-foot span of three lines as they cross the river near Aberdeen, in Grays Harbor County. Installation of two 115kV circuits and one 69kV circuit is scheduled to begin in late July, replacing copper conductors.

The low-sag characteristic of 3M ACCR also will create greater clearance between the transmission lines and fiber optic cable running just beneath them.

3M ACCR, which had its first commercial application in 2004, is now in use by dozens of utilities of all sizes and types in the U.S. and six other countries, including other municipal utilities in California and Colorado.

The conductor is most often used for line upgrades in areas where new construction or expanded rights of way would cause environmental disturbance or pose difficult social and logistical issues, in both rural settings and dense urban areas.

Among public utilities, Silicon Valley Power, owned by the city of Santa Clara, Calif., completed its second upgrade installation last year; Platte River Power Authority, jointly owned by four municipalities north of Denver, installed ACCR to increase the capacity of a line linking Fort Collins and Loveland, Colo.

And, in the desert southwest, Aha Macav, a tribal-owned utility centered in Needles, CA, applied the ACCR on a new line that connects to the Western Area Power Administration’s Colorado River line in western Arizona, which also has been upgraded with the ACCR.

3M ACCR was developed with the support of the U.S. Department of Energy, which tested the conductor at its Oak Ridge National Laboratory in Tennessee, and with early contributions by the Defense Advanced Research Projects Agency.

The ORNL tests demonstrated that the conductor retains its integrity after exposure to temperatures higher than the rated continuous operating temperature of 210 degrees Celsius and the emergency operating temperature of 240 degrees Celsius. It has the durability and longevity of traditional steel core conductors, even when operated continuously at high temperatures.

The conductor’s strength and durability result from its core, composed of aluminum oxide (alumina) fibers embedded in high-purity aluminum through a highly specialized and patented process. The constituent materials can withstand high temperatures without appreciable loss in strength, even over long periods of time.

Also, since 3M’s ACCR is based on aluminum, it is not as susceptible to environmental conditions such as moisture or UV exposure as are other traditional conductors, and it has the corrosion resistance typically associated with aluminum-based conductors.


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