All Aluminium Alloy Conductor (AAAC)
All Aluminium Alloy Conductor (AAAC) is made from aluminum-magnesium-silicon alloy of high electrical conductivity containing Magnesium (0.6-0.9%) & Silicon (0.5-0.9%) Aluminium Alloy 6201 with minimum conductivity is the most preferred choice of matrial for this type of conductor.
The 6201 Alloy rod of 9.5mm diameter is drawn to an intermediate size and coiled. The coil is thereafter placed in a large electrically heated furnace with forced air circulation. The coil is soaked at predetermined temperature for a fixed period of time wherein the precipitated alloying elements are brought back into solution and thereafter it is frozen in solution by quenching the coil in water without allowing the alloying elements to re-precipitate. The solutionised coil is dried and further drawn down to the final size for manufacturing the required AAAC. The solutionised coil is given time to attain required strength and care is taken to ensure that the solutionised coil does not harden more than the prescribed limit.
The drawn wire is further aged in an electric annealing furnace at specified temperature and duration, so as to relieve the built up stresses in the wire due to the wire drawing process. The wire after aging will attain the desired strength and conductivity. The wires are then stranded to manufacture the alloy conductor. Due to its higher strength pre-formers and post-formers are used whilst stranding. At various stages of the manufacturing process, regular inspection and tests are carried out to ensure that the rod/wire at each stage of the process attains the required physical characteristics.
Advantages of AAAC over Aluminium Conductor Steel Reinforced (ACSR) Conductor are as follows:
o AAAC exhibits excellent corrosion resistances especially in polluted and corrosive locations such as sea coasts and Industrial Estates/Zones
o AAAC is homogeneous and therefore there is no bi-metallic effects as compared to ACSR
o AAAC has higher power rating typically between 15 to 20% compared with ACSR of equal size.
o AAAC has higher life compared to ACSR.
o The surface hardness of AAAC is 80 Bhn compared to 35 Bhn for ACSR resulting in reduced damage to surface during handling and stringing thereby leading to lesser corona losses and radio interference at EHV.
o AAAC are stable up to 90ºC against ACSR Conductor which are stable up to 80ºC.
o AAAC has higher strength to weight ratio compared to ACSR of the same size. Designers have the options of longer span lengths which results in savings in installation of these types of conductors compared to the traditional ACSR.