ACSS Trapezoidal Wires ASTM sizes New
SYSTEM RELIABILITY & FLEXIBILITY: ACSS conductors allow Utilities to operate their lines at normal day to day electrical loads, while enabling severe contingency/emergency ratings. ACSS permits important increments of ampacity when compared with similar in size conventional conductors (ACSR / AAAC) by operating at high temperatures up to 250 ºC, without any risk of thermal degradation. Several alternatives are available. Compact designs constructed of fully annealed trapezoidal wires (equivalents in area or in diameter) or designs with round wires. Unlike ACSR, the mechanical responsibility and sag and tension performance of ACSS conductors lies mainly on the steel core.
StandardsInternational : EN 50540
National : ASTM B 857
ACSS/TW conductors are made of fully annealed (0-tempered) aluminum trapezoidal wires wrapped around a 7 or 19 wires steel core. In order to avoid any risk of thermal degradation and to enhance resistance against corrosion, steel wires could be coated by Zn-Al Mischmetal alloy or aluminum clad. Several strength grades of steel are available.
The technology is well-known and proven since many years. Nexans can also deliver compatible accessories and provide assistance on site during installation.
The conductor mechanical behavior is governed by the steel core. When operation at high temperature or after first wind or ice loads, the soft aluminum wires will elongate plastically and transfer all the mechanical responsibility to the steel core. In such a way, the conductor will behave according to the thermal expansion coefficient and modulus of elasticity of the core.
ACSS/TW is an ideal conductor for re-conductoring applications. It can double the ampacity of an equivalent ACSR by operating continuously at temperatures up to 250°C (large up-grading), solving emergency situations or even N-2 contingency ratings, minimizing black-out risks due to temporary bottle necks. Also it is a good option to prevent future demand growth or to evacuate energy from distributed new renewable power plants by taking advantage of existing lines without applying for new permissions and maintaining existing structures and corridors.
Additionally, this conductor present negligible long-term creep and very good self-damping properties. When using a compact design equivalent in area, the resulting ACSS/TW will present lower outer diameter. In such a way, it is possible also to minimize vertical and transversal loads on existing structures due to ice and wind.
Please download document ACSS TW ASTM B 857 for detailed characteristics.