Celanese Corp. and wire and cable producer Southwire Co. LLC have developed overhead electric transmission lines made from thermoplastic composites, to replace the traditional aluminum conductor and steel-reinforced lines.

Called the C-7 Overhead Conductor, the power line uses a bundled strand composite core of Celstran long-fiber reinforced thermoplastics combined with heat-resistant Fortron polyphenylene sulfide, and capped with a layer of PEEK (polyetherether ketone).

The bundle of cables is encased in jacketing made of aluminum or an aluminum-zirconium alloy.

Celanese and Southwire introduced the lighter-weight composite power lines earlier this year, after seven years of development. Celanese highlighted the application at its booth during JEC Americas in Atlanta in May.

Benefits include a minimal increase in line sag under high power transfer, thanks to minimized thermal expansion. The so-called stranded core design means there is no single point of possible failure, which can happen with monolithic cable constructions.

Southwire, based in Carrolton, Ga., said the life expectancy of the composite wire is more than 40 years.