In 2003, CTC Global, based in Irvine, California, U.S., introduced a high-capacity, low-sag aluminum conductor composite core conductor, known as ACCC, to boost the capacity of new or thermally constrained transmission and distribution lines (ACCC has been in commercial production since February 2006).
CTC replaced the conventional steel core with a hybrid carbon and glass fiber core, derived from a mature aerospace composite system. The ACCC core is significantly stronger than steel and has a coefficient of thermal expansion that is about 10 times less than steel. The greater strength permits use of fully annealed aluminum for better conductivity (compared to hardened or alloyed aluminum), and the ACCC core’s negligible thermal expansion mitigates thermal sag under extreme load conditions (doubling capacity 180°C [356°F]).
The composite core weighs about 75% less than steel, allowing the incorporation of about 28% more aluminum in any diameter (using compact trapezoidal strands) without a weight penalty. When compared to other conductors of the same diameter and weight, the added aluminum and improved conductivity allow the conductor to run cooler to carry 30% greater current at the same temperature. The cooler operating temperature reflects a reduction in line losses of 25% to 40%, depending upon actual load.
ACCC’s conductivity and resistance to thermal sag allow it to carry very high levels of current at higher operating temperatures during peak demand or emergency conditions. Higher capacity, reduced sag and lighter weight also translate into lower project costs. These attributes provide economic advantages when upgrading an existing line with minimal structural modifications or installing a new line with fewer or shorter structures.
The conductor also offers improved self-damping and corrosion resistance, making it ideal for any project where efficiency, capacity, reliability, economics and life-cycle costs are key design objectives. Nearly 100 utilities have strung more than 22,000 km (13,670 miles) of ACCC conductor at more than 250 project sites worldwide.
CTC Global continues to develop new conductors based on its composite core technology and recently launched a new core, ACCC/ULS, designed for exceptional performance in heavy ice loads and ultra long spans.
For more information, visit www.ctcglobal.com.