ACSR/AW (Aluminum Conductors Aluminium-Clad Steel Reinforced)

Effect of Short Circuit on Overhead Ground WireAssuming complete absorption of heat by the ground wire

20 degree C, D.C. Resistant:7 No. 8 AWG Alumoweld, .446 ohms/1,000 feet3/8-inch steel, 1.140 ohms/1,000 feet

Temperature Coefficient of Resistance:7 No. 8 AWG Alumoweld, .0036/degree C3/8-inch steel, .0035/degree C

This graph compares overhead ground wire composed of seven .120-inch Alumoweld wires with a steel strand of the same size. To raise the temperature of the Alumoweld strand to 400 degrees Fahrenheit for a fault of six cycles duration would require a 12,000 ampere fault, as compared to a 7,200 ampere fault for steel.

A 10,000 ampere current fault would raise the temperature of Alumoweld strand to 400 degrees Fahrenheit if held for nine cycles; but the steel strand would reach the same temperature in only three cycles.

The high conductivity of Alumoweld overhead ground wire provides additional benefits above and beyond the function of direct stroke protection. Alumoweld's conductivity reduces both the zero sequence impedances and the 60-cycle earth potentials at structures resulting from phase-to-ground flashover.

This assurance against corrosion is obtained through the application of a thick covering of pure aluminum which provides a substantial barrier of protective metal. This minimum cladding thickness of Alumoweld is ten percent of the radius of the wire. The cladding has a continuous, strong metallic bond to the steel core and will not crack or flake. In fact, damage to the cladding by mishandling must be severe to expose the steel core.

On the other hand, thin protective coatings like those found in aluminized steel can be damaged to the point of steel exposure even by ordinary construction methods; resulting in progressive deterioration of the coating and eventual rusting of the steel.

Similar and confirming results have been obtained by field tests conducted since the introduction of Alumoweld over 40 years ago. These field tests encompass all types of exposure including marine, industrial, and rural; and have been evaluated by our own staff and by independent researchers. Sites for field tests include those considered most severe from a corrosion standpoint. Further proof of this corrosion resistance has been provided by the millions of pounds of Alumoweld which have been installed on important lines throughout the world.

In addition to superior conductivity and corrosion resistance, Alumoweld strand also provides strength equal to or greater than other overhead ground wires. Figure 2 below compares the strength of Alumoweld to that of various grades of steel strand. Tensile strengths of the individual wires of the commonly used sizes of Alumoweld approach 200,000 pounds per square inch. When used in a strand for overhead ground wire, this high strength permits smaller sags, increased mid-span separations, and greater safety under storm loading conditions.