Aluminum wire

The article describes the composite electrotechnical material of aluminum-copper, the technology of its manufacture and application.

In the electrotechnical literature, in the descriptions of the material of the conductive conductors of electric wires and cables, one can find the phrase: aluminum-copper conductor. What kind of material is aluminum-copper?

The information offered on the Internet on this issue is very scarce. But still in the electrotechnical GOSTs of the eighties (during the former USSR), along with copper and aluminum, one more must be present conductive material - aluminum-copper. This suggests that in pre-perestroika Russia, aluminum-copper was considered a promising technical find.

Indeed, aluminum-copper has some advantages that make this material attractive for use in everyday life and industry. But first, a brief look at some custom characteristics of copper and aluminum conductors.

Copper:

• low resistance to electric current flow;

• formed in vivo on the surface of the conductor, the film of copper oxide does not impede the flow of current through the contact area of ​​the conductors (low transition resistance);

• high mechanical strength, including in places of contact joints; easy to solder, tin, welding using conventional tools and materials;

• copper conductors, unlike aluminum, do not require lubrication when installing collapsible joints or when mounting by crimping;

• the high cost of producing copper and the final product.

Aluminum:

• aluminum is lighter than copper more than three times;

• electrical conductivity of aluminum is almost two times lower than that of copper;

• the oxide film on the surface of the aluminum conductor has the worst electrical conductivity (not strictly speaking, aluminum oxide is an insulator. And if the film thickness was not a millionths of a centimeter, we would not talk about aluminum as a conductor);

• metal welding is possible in an inert gas environment, soldering - using special fluxes and solders;

• to ensure long-term reliable connection, when installing connections of any type (except welding), it is recommended to clean the surface of the conductor and lubrication with a neutral lubricant (petroleum jelly) of the contact zone;

• the cost of aluminum wires is several times lower than the cost of copper.

Actually, the small specific gravity and low cost of aluminum production prompted manufacturers to find a compromise option, which is aluminum copper.

Essence copper-copper conductor - aluminum core clad with copper. Please do not confuse cladding and copper plating by electrochemical deposition. In the second case, it is impossible (or very expensive) to achieve a sufficiently thick, equally strong layer of copper on aluminum. By cladding, 10, 20, or 30 percent of copper by volume is applied to the surface of the conductor, while for different manufacturers these figures vary by two to five percent.

Production technology bimetal wire lies in the thermomechanical connection of an aluminum core and a copper sheath.

First, a flat tape of calibrated dimensions is made from electrical copper. Then, on special machines, a copper tape is wrapped in an aluminum base so that the joint of the resulting copper sheath is located along the future conductor. (Some technologies provide for subsequent welding of the formed joint).

The resulting workpiece is heated and stretched through a series of special rollers calibrated with some step.The result is a composite material of copper and aluminum, which has the properties of both metals. Then it can be processed by drawing to obtain wires of a smaller diameter, while the ratio of metals in the conductor is maintained.

If the conductivity is average between the conductivities of the two metals, the surface of such a material has all the properties of copper, which means it does not form high-resistance surface oxides, which reduces the transition resistance of the compounds.

Copper wire

Aluminum-copper wires and cables in the power supply system are cheap, weigh much less than copper, and are used almost everywhere where aluminum wire products are applicable. In addition, they are widely used in the automotive industry, as they provide a substantial, up to forty percent, reduction in wiring weight.

Shields of high-frequency cables are made from aluminum-copper conductors, facilitating them and cheapening production. The use of the "skin effect" (at frequencies above 5 megahertz, the electric current spreads over the surface layers of the conductor) is based on the use of copper-alloy wire in coaxial and network cables when building the lower segments of local networks.

In the last example, the keywords are: lower segment. The fact is that at high load, these cables do not provide the necessary bandwidth when transmitting digital data, and some unscrupulous manufacturers and sellers are silent about the composition of the conductors.

The same situation is possible when purchasing electrical wires and power cables. A simple way out is to scrape off the top layer of the wire (cable core) with a knife. In addition, if the cable designation corresponds to the product, then the first letters AM in the designation of domestic brands will indicate the material of the core - aluminum-copper.

The use of aluminum-copper cables in the everyday practice of an electrician also has some features: an aluminum wire can always be replaced with an aluminum-copper cable of the same diameter, but if it still becomes necessary to replace a copper wire, it is necessary to use an aluminum-copper wire with a large diameter, which follows from standard series 1; 1.5; 2; 2.5; 3; 4; 6; 10 mm. sq.

Thus, when certain simple rules are followed, alumino-copper cable products can significantly reduce costs when performing electrical work.

P.S. According to foreign data, aluminum-copper is less attractive to thieves, since it is not in demand among buying firms because of the high cost of the subsequent processing of non-ferrous scrap to separate copper and aluminum. Interesting, and how are we?