ACAR Conductor IEC 61089

ACAR Conductor is a bare overhead composite stranded conductor combining a hard-drawn aluminium envelope with an aluminium-magnesium-silicon alloy core, both single-metal-family. The alloy core contributes the additional tensile reinforcement while the A1 envelope preserves the conductivity-to-area ratio of AAC, producing a conductor with higher rated tensile strength than AAC, lower mass than ACSR, and the corrosion resistance of an all-aluminium-family construction without any steel content.

Conductor Construction

• Outer envelope: Round hard-drawn aluminium wires conforming to IEC 889, designated A1.
• Alloy core: Round aluminium-magnesium-silicon alloy wires conforming to IEC 104 — type B (designated A2) or type A (designated A3) — providing the additional tensile reinforcement.
• Stranding: Concentric lay around a multi-wire alloy core, with adjacent layers stranded in reverse directions; the outside envelope layer is right-hand lay unless otherwise specified.
• Alloy-core lay ratio: 10 to 14 for the outside core layer; 10 to 16 for inner core layers.
• Aluminium-envelope lay ratio: 10 to 14 for the outside envelope layer; 10 to 16 for inner envelope layers.
• Wire joints: Aluminium- and alloy-wire joints are limited to the IEC 61089 joint-count schedule (2 joints per length for single-layer up to 5 for four-layer aluminium conductors) and spaced not less than 15 m apart. For A2 and A3 alloy material, annealing of cold-pressure joints is practiced in some countries.
• Surface: Free from imperfections visible to the unaided eye such as nicks or indentations.

ACAR (A1/A2 and A1/A3) Stranding Configurations

Within the IEC 61089 ACAR family, type A1/A2 pairs the hard-drawn aluminium envelope with a lower-strength type B alloy core, while type A1/A3 uses a higher-strength type A core. For the same code number and stranding, A1/A3 delivers a higher rated tensile strength than A1/A2 at marginally higher mass; the d.c. resistance is essentially the same for both at a given code number, with A1/A3 a small fraction higher because type A alloy has slightly lower conductivity than type B. The stranding ratio between envelope and core wires further lets the designer trade strength against conductivity: a 30/7 stranding emphasises conductivity (more A1 envelope), while an 18/19 stranding emphasises tensile strength (more alloy core) at the same code number.

All sizes, stranding configurations, nominal masses and rated tensile strengths are calculated in accordance with IEC 61089. For composite ACAR conductors the rated tensile strength is taken per IEC 61089 Clause 5.7.3 as the sum of the tensile strength of the A1 envelope plus 95% of the tensile strength of the A2 or A3 alloy core — a definition that recognises the lower elongation at break of the alloy core relative to the hard-drawn aluminium envelope. Conductor breaking-strength testing requires withstand of not less than 95% of this rated value without wire fracture.

Typical Applications

• Bare overhead medium-voltage distribution feeders (10 kV through 35 kV) requiring higher tensile strength than AAC over long spans
• Overhead high-voltage transmission lines in coastal, marine and chemical-industrial atmospheres where a steel core would suffer galvanic corrosion
• River crossings, valley crossings and other long-span installations where a single-metal-family construction is preferred over ACSR
• Rural and last-mile electrification networks where light weight, corrosion resistance and moderate tensile reserve are jointly required
• Reinforcement of existing overhead lines where tower geometry fixes the span length and a stronger conductor than AAC is required without the additional mass of a steel core
• Overhead networks designed under IEC, regional or national grid codes that specify all-aluminium-family construction for environmental, operational or fatigue-life reasons

ACAR manufactured to IEC 61089 is cross-referenced to GB/T 1179 (JL/LHA series for aluminium-conductor-alloy-reinforced configurations) in the Chinese market, and is functionally equivalent to ASTM B524 (ACAR with 6201-T81 alloy core, corresponding most closely to A1/A3 configurations) and BS EN 50182 ACAR variants — allowing the same conductor to be supplied against multiple international procurement standards under a single IEC 61089 production specification.