| Bekaert is a specialist in metal transformation and coatings. With about 17,500 employees and 96 production sites in 29 countries, the company achieves a turnover of 2,8 billion Euros. An important part of this turnover is achieved with steel wire. Bekaert has seen a growing tendency to replace existing conductors with new ones with a higher current carrying capacity at equal weight, diameter and sag. A popular method to increase a conductor�s current carrying capacity is to operate it at higher temperatures, but this may cause some problems on ACSR (Aluminium Conductors Steel Reinforced) conductors. The hard drawn aluminium wires become annealed and loose their strength, thus jeopardising the conductor�s mechanical strength and increasing sag. The zinc coating of the core wires does not withstand high-temperatures and will come off the wire. The steel core cannot be used efficiently, because the aluminium wires only stand 1% elongation and steel reaches its full strength at 3-4%.
To cope with this, the ACSS (Aluminium Conductor Steel Supported) concept was developed, which implicates that the conductor is heated above 250�C in the factory, thus annealing the aluminium wires. This yields an electric conductivity which is 3% better, as well as a much higher elongation at break (20 to 30% instead of 1%). This means that the steel wires can be used at full strength. Moreover, ACSS features considerably lower sag than ACSR at equal diameter and conductivity.
Bekaert�s contribution is in the development of Bezinal� coated steel wires because:
- Bezinal� contains about 94% zinc and 5% aluminium and is temperature resistant;
- Bezinal� has a 2 to 4 times better corrosion resistance than zinc, which even improves after heating;
- Bezinal� distinguishes from �exotic� coatings by that it can be applied in a relatively simple, industrial process.
Regardless the coating, Bekaert can offer a wide range of tensile strengths, even above 2,000N/mm2. Thanks to wires with higher tensile strength, it is possible to reduce a conductor�s steel section and increase its aluminium content. This reduces the electric resistance.
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