Flat Wires
Annealed bare rectangular (strip) copper and aluminium wires, for applications insulated on the winding line.
Bare conductor is delivered without any factory-applied insulation; it is a flat or round product drawn from electrolytic copper or a high-conductivity aluminium alloy. It is used directly in transformer coils where insulation is applied on the winding line with tape or paper, in reactor and busbar manufacture, and in producing current-carrying connection elements.
Annealing rearranges the conductor's crystal structure; hardness drops, elongation at break rises, and the conductor takes shape in tight-radius windings without cracking. Copper conductors are supplied to EN 13601 and ASTM B49, aluminium conductors to ASTM B233; on flat sections the corner radius is kept within standard tolerance so the insulation seats properly.
Flat Wires Products
Bare Rectangular Aluminium Conductor
ISO-AL-BAR-FTechnical Information
Key characteristics:
- Copper conductivity: 100% IACS and above (annealed Cu-ETP)
- Aluminium conductivity: about 61% IACS (EN AW-1370)
- Elongation at break: copper ≥ 30%, aluminium ≥ 25% (annealed condition)
- Flat-section corner radius: 0.30 – 1.60 mm depending on thickness
- Delivery: wooden or steel reels, drums, cut-to-length on request
There is no single right answer to the question "copper or aluminium?". Copper, offering higher conductivity at the same cross-section, is preferred in machines with limited window area; aluminium, standing out in conductivity per unit weight, provides an economical solution in dry-type transformers and large-section windings where weight is decisive. When switching to aluminium, about 60% more section is needed for the same current; this affects the bobbin window, cooling channel and connection technique decisions together.
The flat (rectangular) section, giving a higher fill ratio in the same window area, is standard in power transformer and large motor windings. The round section is used in small-section, high-turn coils and on automatic winding lines thanks to its easy workability.