The choice of one conductive material over another is explained by the different uses, as well as the safety and efficiency requirements that the electric cable must satisfy. Copper still represents one of the most used conductors in the construction of electrical systems: let's see the reasons and what are the advantages of using copper in electrical cables.
The properties of copper as a conductor
Electric cables are subjected to important stresses (and are therefore cause of risks): the electricity that passes through them can be dispersed, causing damage to things and people; heating the conductor can cause fires in the system and electrical appliances, and so on.
Choosing a suitable conductor for the cables is therefore an important premise when you want to guarantee the best safety conditions, without sacrificing the capacity and efficiency of the electrical connections. These reasons explain why copper is still the most used electrical conductor in view of its excellent characteristics.
This metal can boast the best electrical conductivity, with the exception of silver, which, of course, does not have the same costs and therefore that’s an additional pro for copper. Furthermore, the ductility of copper allows numerous possibilities of use: it is possible to draw the material in spinning with extremely thin diameters and, at the same time, the simple lamination and the high weldability make it an excellent material in the most technologically advanced productions.
Moreover, copper also has excellent physical qualities which increase its safety level when used in cables. In fact, the metal maintains its mechanical characteristics even at low temperatures and has excellent levels of resistance to oxidation when it comes into contact with the atmosphere: copper, in fact, is only penetrated by oxidation if the surface oxide film is removed (this explains the need to use tin alloys in insulated cables).
Finally, copper presents, for the same characteristics with other metals, low costs, both as regards its availability and processing, and for the extreme ease of reuse of the unused scrap.
Copper alloys in electrical cables
In addition to the characteristics of the material that make it an excellent conductor; copper has excellent chemical reagent capacities compared to other metals, making it a perfect material for use in alloys.
The alloy, in turn, can be used in different areas because of its characteristics and therefore the qualities it can ensure. In particular:
- copper and zinc alloys (which give rise to brass) have excellent workability, which makes them very versatile conductors in a large number of applications;
- copper and beryllium alloys, on the other hand, have excellent mechanical properties, with a good breaking load and excellent conductivity, which makes them prefer to be used for contacts and, in general, for components subjected to fatigue;
- bronze (copper and tin alloy) also has good mechanical properties and electrical conductivity.
In general, copper and its alloys are widely used, as well as for the production of electrical cables (low, medium and high voltage), due to their ability to transmit both small and large powers, also for the production of other electrical components, such as:
- collectors where the contacts are subjected to mechanical stress;
- winding material of transformers;
- coating material of rotating machines.
Copper or aluminum? why copper is still preferred
In addition to copper and its alloys, there are other materials that can be used for the purpose of conducting electricity, depending on the concrete applications (industrial, civil or military). Among these, aluminum represents the most direct competitor of copper, especially with regard to its industrial uses.
Advantages of aluminum compared to copper
Aluminum, used as an electrical conductor, has some advantages over copper:
- it is much lighter than copper, a feature that increases its various possibilities of use;
- has a higher resistivity than that of copper;
- the production of aluminum conductors is, in principle, less expensive than that of copper conductors, thanks to a greater diffusion of the first metal and its ease of extraction / processing.
It is therefore necessary to clarify the reason why, given the apparently better characteristics, aluminum has never found the same "success" as its direct competitor. In fact, the advantages of copper in the use of electrical cables continue to favor it over other conductive materials.
The problems of aluminum
The main problem of aluminum is that this material has a very low melting temperature: around 660 ° C, compared to more than 1,080 ° C for copper. This datum certifies the impossibility of using this conductor whenever there is a thermal risk.
Furthermore, aluminum is less easily combinable with other metals and gives greater welding difficulties: this is due to the fact that the relative oxide has a very high melting temperature, higher than 2000 ° C.
Moreover, unlike copper, despite being a particularly malleable metal, aluminum cannot be drawn, therefore, its use is not recommended when very thin wires are to be made.
Finally, aluminum is more subject to the risk of oxidation: in fact, in contact with the atmosphere it tends more easily to cover itself with an insulating oxide (alumina), which has a tendency to crack and break and could determine a greater fragility than cables made of copper.
Copper therefore, with its still unmatched characteristics, considered as a whole, is confirmed as the metal mainly used for electrical cables and still does not find a competitor who knows how to compete for the podium.