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C T J U N E 2 0 1 4 1 5 COMPOSITES WATCH Composites WATCH A new composite solution cuts overall utility investment in power transmission while in the realm of power generation, forecasts go up for wind energy. Carbon fber featured in new electrical transmission cable Celanese Corp. (Dallas, Texas) and Southwire Co. LLC (Carrollton, Ga.), North America's largest wire and cable producer, have intro- duced a new option for utility transmission lines: the C 7 Over- head Conductor, featuring a lightweight and high strength-to- weight, multi-element composite core of Celstran continuous fber-reinforced thermoplastic rods (CFR-TPR), made by Cela- nese. Mark Lancaster, Southwire's director of overhead transmis- sion engineering, says the technology behind C 7 was seven years in the making and represents a step-change in overhead wire and cable design and engineering. Te goal, he says, was to develop a product for utilities that want to increase right-of-way capacity without the expense of erecting new infrastructure. Line sag, he says, is the largest limiting factor in how much current can be passed through a utility line. "We wanted to increase capacity of the right of way over the same equipment." Te result is a product that, reportedly, not only increases capacity, but provides cost- avoidance benefts by obviating the need for new towers and poles, a need that would have to be met if increases were attempted with traditional steel-cored conductor cables. Codeveloped by Celanese and Southwire, the conductor cable reportedly nearly doubles the transmission capacity, yet exhibits less sag than an aluminum conductor steel-reinforced (ACSR) ca- ble of the same diameter. How does C 7 compare to other compos- ite-cored conductors already on the market? Michael Ruby, global composites business manager at Celanese, says, "Tis combination of materials provides distinct advantages compared to alternative High Temperature Low Sag (HTLS) technology and conventional conductors." For one, the C 7 core comprises seven (or more, de- pending on cable diameter) 3.2-mm/0.13-inch diameter strands of aerospace-grade carbon fber pultruded with Fortron PPS (poly- phenylene sulfde) from Celanese. Te core is isolated from direct contact with the cable's aluminum conductor strands by an over- wrap of polyetheretherketone (PEEK), which protects the alumi- num from galvanic corrosion and prevents abrasion of the core. Unlike previously introduced solid, composite-cored cabling, the Celstran CFR-TPR core's construction is said to eliminate the po- tential for single-point failure of the C 7 cable: Te bundled core strands and the overwrapped aluminum conductor strands, to- gether, provide structural support redundancy in high-load con- ditions, which means that the failure of one or two or even three strands will not result in cable failure. In addition, Lancaster notes that the carbon fber composite core operates at a generally lower temperature, which maximizes energy throughput and mini- mizes capacity loss. Nonetheless, the carbon fber/thermoplastic core reportedly can operate under hotter conditions (180°C to 225°C/356°F to 437°F) without damage to the line. Tat said, Lancaster points out that the success of C 7 as a re- placement cable product rides on whether or not cable installers can use the same tools and equipment they employ with metal- cored cables. On that subject, C 7 delivers. "Install and repair strategies had to be the same," he says, "so that our customers can seamlessly integrate it into their work environment." ENERGY Source (both photos) | Celanese/Southwire 0614CT CompWatch-OK.indd 15 5/20/2014 7:59:09 AM