Oak Ridge National Laboratory (ORNL) and 3M are hoping for powerful results from a project aimed at making electricity transmission more efficient and reliable.
Researchers from 3M, working with ORNL, are said to be developing a promising replacement conductor for conventional power lines that addresses the problem of power outages caused by power lines that sag under the heat of high current loads.
‘3M’s new composite-core conductor can increase the current-carrying capacity of a transmission line at minimal cost and environmental impact,’ said John Stovall, technical leader in ORNL’s Engineering Science and Technology Division. ‘Its advantage is using existing structures to increase transmission capacity without the cost of a new transmission line.’
The design uses 3M Nextel 650 ceramic fibres, embedded in an aluminium matrix, to make a composite wire that does not stretch as much when heated. An enhancement in the new cables is the addition of zirconium, which makes the aluminium more resistant to deformation at higher temperatures. The aluminium matrix also helps prevent rust in the cable. 3M is working with Nexans and Wire Rope Industries to manufacture the conductor.
‘The new conductor’s ability to handle greater temperatures will allow more current to be transmitted,’ Stovall said.
ORNL researchers will test 3M’s small, medium and large diameter conductor cables in a field experiment at ORNL.
The tests will evaluate the overall performance of the conductors and verify predictions of computer models by looking at sag and tension data, which includes stress/strain curve and breaking point. Other tests involve assessing conductor accessories that attach the conductor to the towers.
Each test will run from five to six months. The researchers hope to put each conductor through 500 cycles of simulated thermocycling, taking it to peak load and then returning it to normal load, which represents the equivalent of 30 years of peak loads.
The Power Line Conductor Accelerated Testing (PCAT) facility will be a closed loop of approximately 2,400 feet of composite core conductor. A 2MW direct current power supply fed by a transformer will provide current for the site.
‘If the tests show that the new conductor performs well, it could mean that electric utilities will take greater interest in replacing their lines with new cables,’ Stovall said. ‘It also could provide one possible answer to the growing energy demand and transmission bottlenecks.’