Conductors can be presented in a number of ways, one of which is material under specific physical conditions, such as metal bars (bars) that were not designed to be part of electrical circuits. Although not part of an electrical assembly, these materials always retain their steering properties.
Also, depending on the circuit configuration, conductors for residential applications (thin) or cables for underground outlets can be distinguished in electrical distribution systems (thick).
For the purposes of this article, we will focus on the characteristics of conductive materials in their pure state; In addition, we’ll know which conductive materials are most used and why.
Electric conductors are characterized by not offering much resistance to the passage of electrical current through them, which is only possible thanks to their electrical and physical properties, which ensure that the circulation of electricity through the conductor does not induce deformation or destruction of the material in question.
The main electrical characteristics of electrical conductors are as follows:
Electrical conductors must have good electrical conductivity to fulfill their function of carrying electrical energy.
The International Electrotechnical Commission determined in mid-1913 that the electrical conductivity of pure copper could serve as a reference for measuring and comparing the conductivity of other conductive materials.
Thus, the International Annealed Copper Standard (IACS) was established.
The reference adopted was the conductivity of an annealed copper wire with one meter long and one gram of mass at 20 ° C, whose value is equal to 5.80 x 10 7 Sm -1 . This value is known as 100% IACS electrical conductivity and is the reference point for measuring the conductivity of conductive materials.
A conductive material is considered as such if it has more than 40% SIGC. Materials with a conductivity greater than 100% of the SIGC are considered to be materials of high conductivity.
The atomic structure allows the passage of current
The atomic structure allows the passage of electric current, since the atoms have few electrons in their valence shell and, in turn, these electrons are detached from the atom’s nucleus.
The configuration described implies that a large amount of energy is not needed for electrons to move from one atom to another, facilitating the movement of electrons through the conductor.
This type of electron is called free electrons. Its disposition and freedom of movement along the atomic structure is what makes the circulation of electricity through the conductor conducive.
The molecular structure of conductors is composed of a tightly knit network of nuclei, which remain practically immobile due to their cohesion.
This makes it conducive to the movement of electrons that are remote within the molecule, as they move freely and react to the proximity of an electric field.
This reaction induces the movement of electrons in a specific direction, which gives rise to the circulation of electric current through the conductive material.
Subject to a specific charge, conductive materials eventually reach a state of electrostatic equilibrium in which charge movement within the material does not occur.
Positive charges clump together at one end of the material and negative charges pile up at the opposite end. The displacement of charges towards the conductor surface generates the presence of equal and opposite electric fields inside the conductor. Thus, the total internal electric field within the material is nil.
Electrical conductors must be malleable; that is, they must be able to deform without breaking.
Conductive materials are often used in domestic or industrial applications where they must undergo bending and bending; Therefore, malleability is an extremely important characteristic.
These materials must be resistant to wear, to withstand the conditions of mechanical stress to which they are normally subjected, combined with high temperatures due to current circulation.
When used in a residential, industrial application or as part of an interconnected power supply system, the conductors must always be covered with a suitable insulating layer.
This outer layer, also known as an insulating coating, is needed to prevent the electrical current flowing through the conductor from contacting people or objects around it.
Types of electrical conductors
There are different categories of electrical conductors and, in turn, in each category are the materials or media with the highest electrical conductivity.
By excellence, the best electrical conductors are solid metals, among which copper, gold, silver, aluminum, iron and some alloys stand out.
However, there are other types of materials or solutions that have good electrical conduction properties, such as graphite or saline solutions.
Depending on the way in which electrical conduction is carried out, it is possible to differentiate three types of materials or conductive media, detailed below:
This group consists of solid metals and their respective alloys.
Metallic conductors owe their high conductivity to clouds of free electrons that favor the circulation of electrical current through them. Metals release electrons located in the last orbit of their atoms without investing greater amounts of energy, which facilitates the leap of electrons from one atom to another.
On the other hand, alloys are characterized by high resistivity; that is, they have a resistance proportional to the length and diameter of the conductor.
The most used alloys in electrical installations are brass, an alloy of copper and zinc; tinplate, an alloy of iron and tin; copper and nickel alloys; and chromium and nickel alloys.
They are solutions made up of free ions, which help in the electrical conduction of the ionic class.
Most of the time, these types of conductors are present in ionic solutions, as electrolytic substances must undergo partial (or total) dissociations to form the charge-carrying ions.
Electrolytic conductors base their operation on chemical reactions and the displacement of matter, which facilitates the movement of electrons along the circulation path made possible by free ions.
In this category are gases that have previously undergone an ionization process, which makes it possible to conduct electricity through them.
The air itself acts as a conductor of electricity when, when a dielectric failure occurs, it serves as an electrical conductor medium for the formation of lightning and electrical shock.
It is widely used in overhead electrical transmission systems because, despite having 35% lower conductivity compared to annealed copper, its weight is three times lighter than the latter.
High voltage outlets are usually covered with an outer surface of polyvinyl chloride (PVC), which prevents the conductor from overheating and isolates the passage of electrical current from the outside.
It is the metal most used as an electrical conductor in industrial and residential applications, given the balance between its conductivity and price.
Copper can be used in low- and medium-gauge conductors, single or multi-wire, depending on the ammeter capacity of the conductor.
It is a material used in electronic assemblies of microprocessors and integrated circuits. It is also used to manufacture battery terminals for vehicles, among other applications.
The conductivity of gold is approximately 20% less than the conductivity of annealed gold. However, it is a very durable and corrosion resistant material.
With a conductivity of 6.30 x 10 7 Sm -1 (9-10% greater than the conductivity of annealed copper), it is the metal with the highest known electrical conductivity to date.
It is a very malleable and ductile material, with a hardness comparable to gold or copper. However, its cost is extremely high, so its use is not so common in the industry.