Silicon Valley Power, the 112-year-old electric utility established by the city of Santa Clara, California, will install the 3M Aluminum Conductor Composite Reinforced (3M ACCR) on an existing line to substantially boost capacity without having to enlarge the towers or the right of way.
Silicon Valley Power will re-conductor a 60kV line that principally links its Scott Receiving Station with the Northwestern Substation, through a narrow right of way in an urban neighborhood. Reconductoring with 3M ACCR allows the line to be upgraded with minimal disturbance to the neighborhood. The utility serves just over 51,000 residential, commercial and industrial customers in a 19-square-mile area with a population exceeding 115,000. Its service area covers a significant portion of the Silicon Valley technology community, and includes major corporations such as Intel, Sun Microsystems and Applied Materials.
“We needed a way to significantly increase transmission capacity without the extra cost of making major structural changes,” says Kevin Keating, manager of engineering for Silicon Valley Power. “3M ACCR fit our needs exactly and at quite a savings over other alternatives.”
Silicon Valley Power joins a growing roster of utilities that have deployed 3M ACCR in a variety of circumstances in which greater capacity is needed to relieve transmission bottlenecks while minimizing environmental and economic impact, both in urban and rural settings. The list includes Western Area Power Administration; Xcel Energy; Alabama Power, a unit of Southern Company; Arizona Public Service Corp.; Allegheny Power, and Platte River Power Authority in the United States, as well as Shanghai Electric in China, ISA Group’s Companhia de Transmissão de Energia Elétrica Paulista (CTEEP) in Brazil, and British Columbia Transmission Corporation (BCTC) in British Columbia, Canada, among others.
The high-capacity aluminum matrix conductor can carry twice the current of conventional steel-core conductors of the same diameter without larger towers, even across long spans. Its low sag, strength and durability result from its core, which is composed of aluminum oxide (alumina) fibers embedded in high-purity aluminum. The constituent materials are chemically compatible with each other and can withstand high temperatures without adverse chemical reactions or any appreciable loss in strength. The conductor also is highly resistant to corrosion and has the durability typically associated with all-aluminum conductors.
3M ACCR was developed with the support of the U.S. Department of Energy, which tested the conductor at Oak Ridge National Laboratory (ORNL) in Tennessee, and with early contributions by the Defense Advanced Research Projects Agency. The ORNL tests demonstrated the conductor’s integrity after exposure to temperatures even higher than the rated continuous operating temperature of 210 degrees Celsius. In addition to testing installations at Oak Ridge, 3M ACCR has been in use, both in continuous field tests and commercial operation, for several years, under a wide range of harsh climate conditions. The conductor has met all performance and reliability expectations and has never experienced a failure in the field, in either installation or operation.