Aluminum Clad Steel strand 20.3percent IACS

Aluminum Clad Steel strand 20.3percent IACS ASTM B-415 Hard-Drawn Aluminum-Clad Steel Wire
ASTM B-416 Concentric-Lay-Stranded Aluminum-Clad Steel Conductors The reliable, uninterrupted transmission of electrical power is vital to the electric utility industry. Transmission lines carrying large blocks of power must be permanently protected against damage from lightning. Alumoweld overhead ground wires provide the best means of obtaining this protection. They combine conductivity, , and high strength--all of the properties necessary for such assurance. The thick aluminum cladding on each wire offers optimum protection against atmospheric corrosion while providing the conductivity important in proper operation of protective relays. The high conductivity of Alumoweld strand also reduces the temperature rise of the static wire under fault current conditions. Excellent Conductivity
Due to a thick aluminum cladding, Alumoweld overhead ground wire provides one-third the conductivity of an aluminum conductor of equal size, and several times the conductivity of steel. Each Alumoweld product is tested for resistivity, a practice not generally used for steel. This insures known electrical properties in Alumoweld overhead ground wires. These properties are maintained throughout the life of the line, as contrasted to the properties of steel wires with other protective coatings which can deteriorate over time. Such deterioration further reduces the already low conductivity of steel overhead ground wires.   Effect of Short Circuit on Overhead Ground Wire
Assuming complete absorption of heat by the ground wire 20 degree C, D.C. Resistant:
7 No. 8 AWG Alumoweld, .446 ohms/1,000 feet
3/8-inch steel, 1.140 ohms/1,000 feet Temperature Coefficient of Resistance:
7 No. 8 AWG Alumoweld, .0036/degree C
3/8-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. Corrosion Resistance
Numerous laboratory and field tests confirm the excellent of Alumoweld strand. Its strength and conductivity are permanent in any atmosphere where aluminum is satisfactory; especially those known to be corrosive from industrial or atmospheric conditions. 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. Laboratory and Field Tests
Laboratory tests on Alumoweld have included salt spray, 100 percent relative humidity, and flue gas tests. In all of these, the wire and strand have performed extremely well. 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. Strength Comparable to Steel
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.   Light Weight
Directly related to strength and sag performance is the lighter weight of Alumoweld strand. Due to its thick cladding of aluminum, Alumoweld is 15 percent lighter than a steel strand of equivalent size. This lighter weight, combined with high strength, permits Alumoweld strand to be strung to the same sags as steel with correspondingly lower tensions and lower stresses on the towers or supporting structures. Sag Data
Alumoweld overhead ground wires may be sagged to provide the proper mechanical safety and lightning protection for any power conductor. Refer to the National Electrical Safety Code for sag data specifications for all three loading districts in the United States. Such data is presented based on the maximum everyday stress limits specified by this code, and will provide minimum sags. Also available are special data based on lower everyday stress limits. These call for greater sags and correspondingly lower tensions which may add certain economies to the line design and will provide greater safety for lines in areas where vibration may be a problem.