UK manufacturer and supplier of quality copper terminals, busbars, earth bars, coils, heat sinks and braids to the electrical industry.

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Yes, we also manufacture in Aluminium!

Aluminium for Electrical Applications 140624

Bus-Bars, Connectors and Structures

Aluminium’s light weight (30% that of copper) and low cost make it by far the most economic choice for conducting electricity over any significant distance. Although the resistivity is somewhat higher (58% above copper) using extra material in the cross-section still results in equivalent bars at about 20% the price of copper. The skin-depth penetration into aluminium is also about 40% higher with aluminium compared to copper and this can mean that transformers and bus-bars used for high frequency power conversion (e.g. IGBT drives etc.) can be designed and built with fewer divisions, thicker laminates and, again, lower material costs.

The main factors affecting electrical applications of aluminium are its surface properties and strength.

Aluminium readily forms a very robust oxide that prevents electrical conduction. Its rapid reaction with air, particularly in the damp and marine environments, means that corrosion can be a real problem and even lead to significant material loss. Corrosion is further accelerated in contact with base metals such as copper. Coating aluminium by electroplating is an expensive complex process that does not eliminate all surface problems but can stabilise the surface for some applications. Co-extruded or clad composites with a substantial surface copper layer are also available and do offer a compromise material whose surface is stable and , like solid copper, may be electroplated by conventional processes. Machined interconnection parts, used within equipment, can be protected by a thin surface layer of oil or grease that will normally enhance the stability of a properly-tightened connection. In fact, using machined collars etc. to provide an interconnection “mesa” is an excellent precaution for controlling the compression and integrity of interconnections between aluminium bus-bars and components and prevents the elongated capillary spaces that otherwise form potential moisture- and corrosion-traps between simple bolted bus-bar joints.

The low mechanical strength of aluminium has a significant bearing on its use in stranded conductor cables. Drawing fine continuous wires is very much more difficult with aluminium than copper and this, combined with poor surface properties, mean that flexible stranded cables are more difficult to manufacture and interconnect than their copper equivalents. Compared again to copper, the comparative weakness of aluminium also means that compression terminations must be bulkier in section and longer in their cable-insertion barrel. Although these factors combine to make aluminium frequently a more expensive choice than copper for shorter lengths of compression-terminated flexible cable, it still remains a valid choice for many heavy-duty applications including overhead power-distribution lines and railway traction-supply cables.

On the plus side, the low strength of aluminium makes machining an attractive method of integrating several functions into one component; a concept that has been applied in the aircraft industry for many years. When machined from a solid precursor, heat-sinks, bus-bars and structural features can benefit from greatly improved functional integrity with obvious reductions in interfaces, component count and assembly costs. Please contact us for further details on any of these points.

Laminates
Just a reminder that LML do specialise in the production of laminate bus bars. Laminate bus bars are an engineered component made up of layers of fabricated copper or aluminium giving a level of mechanical flexibility to ease alignment. Please consult us for further details.



Crimp Tools and Die Sets
We are able to supply, so do please get in touch with your requirements.

 

 

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