1250mm2 AAAC Aluminum Alloy Conductor 91/4.49 Bare Overhead Cable for Bulk Power Transmission

At the top of the range, the AAAC 1250 mm² conductor is a ninety-one wire construction of 4.49 mm 6201-T81 alloy strands, with an overall diameter of 49.39 mm, a calculated weight of 3973.7 kg/km, a rated strength of 424.41 kN and a D.C. resistance of 0.0231 Ω/km at 20 °C. Conductors of this size are specified for bulk transmission and for high capacity interconnectors where the number of circuits is limited by wayleave or by the cost of new towers, and where a single large conductor or a bundle is the practical way to move power with acceptable loss. The high strength is essential: it lets the conductor be tensioned to control sag over long spans while keeping the fittings and towers within their design loads.

Losses scale with current squared, so at transmission current levels the resistance difference between sizes becomes a real annual cost. A D.C. resistance of 0.0231 Ω/km and a continuous rating of 1185 A, established at 0.6 m/s wind, 1200 W/m² solar radiation, 50 °C ambient and 80 °C conductor temperature, give a design basis that holds up on long routes. The 424.41 kN rated strength provides the tension margin that long spans demand, and because the conductor is homogeneous there is no steel core to corrode and no bimetal interface to inspect at fittings. The ninety-one wire build produces an unusually smooth surface for a conductor of this diameter, which reduces surface stress and helps where corona and audible noise limits apply near populated areas.

For a conductor this size, the alloy quality and the stranding accuracy decide whether the finished cable can be pulled at high tension without damage. The 6201 charge is verified for magnesium and silicon content and heat treated to T81 so that drawn wire holds 52.5 % IACS conductivity with the required tensile strength; both values are sampled along the coil. Wire is drawn to 4.49 mm and inspected for diameter and surface condition before stranding, with defective wire rejected rather than spliced in. Ninety-one wires are stranded in three layers with lay length, direction and tension controlled layer by layer, and the outer layer is left joint-free because it carries the highest stress at the fittings. Finished lengths are measured, weighed, resistance tested and tensile tested against the 424.41 kN rating. Drums are braced for a conductor weighing almost four tonnes per kilometre, and payoff equipment must be matched to the drum so the conductor does not kink or cross over in the fleet angle.

• 91/4.49 mm stranding: smooth surface and manageable flexibility for a 49 mm conductor
• Rated strength 424.41 kN: tension margin for long spans and high design loads
• D.C. resistance 0.0231 Ω/km: low transmission loss over long routes and high current
• 1185 A continuous rating: stated basis: 0.6 m/s wind, 1200 W/m², 50 °C ambient, 80 °C conductor
• No steel core: no core corrosion, no bimetal interface to inspect at fittings
• Braced heavy drums: transport and payoff planned for 3973.7 kg/km conductor weight

Bulk power transmission lines, high capacity interconnectors where circuit numbers are constrained, long span transmission in difficult terrain, and bundle conductor applications in substation-to-substation links. Fittings, tension stringing equipment and drum handling must be sized for a conductor of this weight and stiffness.

Delivered on braced heavy wooden or steel drums, with flange marking for model, size, stranding, length, standard and batch. Drum length and drum barrel diameter are agreed at order stage so that stringing tension and the permitted bending radius are respected during transport and installation.