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Silicon Valley Power Uses 3M’s ACCR to Raise Transmission Capacity Without Tower Construction

Silicon Valley Power (SVP), the Santa Clara, CA, municipal electric utility, has selected the light-weight 3M Aluminum Conductor Composite Reinforced (3M ACCR) to boost transmission capacity on an existing line without having to enlarge the towers or the right of way. This is SVP’s second installation of ACCR.

3M ACCR. Click to enlarge.

SVP completed installation of the conductor on a 60 kV line along a three-mile city corridor, nearly doubling the power line’s power flow capacity from 850 amperes to more than 1,550 amperes without new construction in a residential and commercial area of the city.

Introduced commercially in 2004 following four years of field testing in a variety of environments, 3M ACCR is in commercial use by utilities throughout the US and in Brazil, Canada, India and China. It also recently launched in the UK. Its primary application is for transmission upgrades in either densely developed or environmentally sensitive areas, where new tower construction would be costly, disruptive and time-consuming.

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 the core, which is composed of aluminum oxide (alumina) fibers embedded in high-purity aluminum. The constituent materials are chemically compatible with one another and can withstand high temperatures without adverse chemical reactions or any appreciable loss in strength. The conductor is also highly resistant to corrosion and has the durability typically associated with all-aluminum conductors.

3M ACCR was developed with the support of the US Department of Energy, which tested the conductor at Oak Ridge National Laboratory, and with early contributions by the Defense Advanced Research Projects Agency (DARPA). The ORNL tests demonstrated the conductor’s integrity after exposure to temperatures even higher than the rated continuous operating temperature of 210 °C.

(A hat-tip to Fred!)




The high operating temperature can be very positive to fight icing rain build up and reduce cable and tower failures.

Doubling or tripling the local network voltage is another way to transport more energy on the same lines/towers.


I would like to see under ground transmission lines. As far as I can tell looking online this can be done, but costs more. We might get less opposition to the lines if this were the case.


How about eliminating the need for doubling tower capacity by offloading some of the residential demand to CHP units???

If greens really want to see lower energy consumption of fossil fuels then how about some serious investment in building viable RPUs - especially in the northern (colder) climates.


CHP and solar can reduce the grid load in a distributed model. It comes down to energy costs and paying for the CHP and solar. Once we see that this investment is better than power plants and distribution, then we can make some progress.

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