Cavo Per Uso Overhead Acsr/Tw Acss/Tw Con Conduttore In Alluminio

ACSS/TW,annealed Aluminium Conductors Steel Supported (ASTM B 857)
Construction
ACSS/TW, a nonhomogeneous conductor, is a trapezoidal shaped wire compact concentriclay- stranded conductor made from aluminum 1350-O wires and round, coated steel core wire(s). ACSS/TW conductors withequal area or equal diameter as compared to ACSS conductors are available for overhead lines. Steel wires are coated with Class A coating of zinc – 5% aluminum mischmetal alloy. Other Classes of coatings are also available for additional protection from corrosion. Standard, High, Extra and Ultra High Strength steel are also available.
 
Specifications
ACSS/TW conductors are manufactured in accordance with the ASTM specification B857.
 
Features
ACSS conductors are preferred over ACSR conductors for specific transmission line
applications:
With zinc – 5% aluminum mischmetal alloy coating on steel wires, ACSS conductors can be operated
up to 250 °C.
ACSS conductors carry more current than ACSR conductors due to:
— Minimum average conductivity of 63% IACS for 1350-O aluminum wires vs. an average conductivity of 61.2% for 1350-H19 aluminum wires in ACSR.
— ACSS conductors can be operated up to 250 °C vs. the maximum operating temperature for an ACSR conductor does not exceed 100 °C.
ACSS conductors are prone to resist the effects of aeolian vibration due to very little or no mechanical load on the annealed aluminum wires.
Long term creep is not a factor when designing with ACSS conductors. In addition, use of ACSS/TW with the equal area design allows equal ampacity in a conductor with approximately 10% smaller diameter over a standard ACSS with same area. This smaller diameter of equal area ACSS/TW conductors helps reduce the effects of ice and wind loading on the conductor.
Alternatively, use of ACSS/TW with equal diameter design provides a conductor in which the aluminum area is increased by approximately 20% – 25% over a standard ACSS with same diameter. This increase
in the cross-sectional area of the conductor reduces its ac resistance by about 15% – 20% and thus, increases its current carrying capacity by about 10%.