A electric wire , or electric cable , is component electric being used for transport of the electricity, in the form of energy or of information. It consists of a conducting, mono-bit or multistranded Matériau , sometimes surrounded by a insulating envelope (plastic, Teflon, etc)

According to its size, it can be employed to transmit electrical signals, or electrical energy. The most used materials generally show interesting characteristics with regard to the Electrical resistance, the Poids, the behavior Mécanique, the Coût.

Theory

lines of transmission

See also: Line of transmission

The line of transmission is a very important theoretical concept in the field of telecommunications, it describes the influence of an electric driver in the transmission of high frequency signals.

Materials used

copper

See also: Copper

Good conductivity, malleable metal.

  • cylindrical Wire:
    • copper is metal more used to make wire and electric cables. One uses it either in cylindrical wire of section mono-bit (rigid) , or in always cylindrical section but multistranded or (flexible) . To make it more flexible, it is used in Alliage with others metals.
    • the copper wire is protected either:
      • By a varnish film, when one uses it for the manufacture of the transformer winding, , electromagnet
      • Or by a plastic layer of coloured, in the majority of the other cases
      • These protections ensure the insulation while preserving the properties of adaptation of form of the wire.
      • Autrefois one used a braid of Coton, rubber and, sometimes from the Papier for the insulation of wire, these techniques disappeared for safety reasons and from cost.
    • the isolated copper wire is often twisted in a cable, comprising of two to several hundreds of wire. These cables sometimes are provided (surrounded) with one or more Blindage made of a Feuille of aluminum and/or of a Tresse of copper. In certain cases, one Weapon the cable with one or more sheets (Strip iron) of Steel, so that it can resist extreme mechanical conditions: cables under ground, cables underwater.

  • Bar.

    • For the distribution large current, in the industrial facilities and the cupboards of electric distribution, one uses copper in Barre S punts. These bars (sets of bars) are used in the place of cables on account of the cost, but also of facility of connection and rigidity.
    • It is simpler to conceive and carry out a good connection between two flat drivers, which enters a cylindrical cable and a rectangular hole.
    • Moreover the set of bars solidarizes the whole of various the Appareil lages which are connected to him, thus preventing a possible defect of fixing due to the vibrations and thermal stresses.
    • These sets of bars are exclusively installed in places reserved for the electrician S. Although seldom isolated, only of the beaconings and the translucent protections imposed since the Années 1980 prevent possible accidents of electrification.

  • Piste coppers of it on support of epoxy or Bakélite, used in the applications electronic putting in plays rather weak electric currents.

aluminum

See also: Aluminum

Good conductivity, light, fairly malleable metal.

  • aluminum is often used in the electricity transmission of great power when the section cable and its length eliminates copper, because of its higher specific mass. It is almost exclusively used in hearts with multiple bits, because of the sections in plays and of its relative rigidity. Its relative facility of breakage during torsions and of handling makes it undesirable in domestic medium.
  • It is used in the place of copper as soon as the constraint weight becomes important: Aeronautical, space conquest, etc

steel

See also: Steel

Average conductivity, great resistance to the stretching, heavy and not very malleable.

  • steel is used, in general, like support of the describing copper or aluminum cables in the cables of great ranges, in order to ensure a tensile strength that the aluminum or the copper would be unable to support without excessive lengthening and rupture.
  • In a more specific way, steel is also used for the transport of energy in the medium Ferroviaire. A Polarité is conveyed by the Caténaire, the other polarity uses like support the Rail S of steel bearings. In the particular case of the Subway, the positive polarity is distributed via a “Rail traction” also out of steel.

money

See also: Money (metal)

Excellent conductivity, noble metal.

  • the money is used to decrease the resistance of contact, in the systems of Connection S and, the systems of Commutation S like the contacts of the relays. It requires however a system of cleaning, generally automatic, to prevent that the Oxydation of surface compromises its good electric conductivity.
  • It is used in certain wire, out of alloy with copper to ensure a good flexibility the wire.
  • It can also be mixed with the gold which ensures a better flexibility and a better conductivity to him while lowering the price of the gold wire. This used in robotics for example to carry out connections of very high degree of accuracy.

gold

See also: Gold

Excellent conductivity, stainless, noble metal.

  • gold is used with parsimony, in very thin layer deposited by electrolysis (a flash ), in the electric systems and, definitely more in electronic.
  • Like the money, it is used to carry out the most perfect possible connection between two independent drivers: contacts of the plug-in electronic charts and plates of contacts of the associated connectors, pastilles of contacts and internal wire of connections of the integrated circuits.

insulators

See also: electrical Insulator

  • Polyethylene
  • Polyethylene-chlorosulfoné (Hypalon)
  • Rubber silicone
  • EPR (Rubber Ethylene-Propylene), largely used for the cables weak and Medium Average in harsh environment.
  • PRC (Réticulé Polyethylene Chemically)
  • Polychloroprène
  • PVC
  • mineral Insulator
  • Insulator HS (without halogen) réticulé
  • Sheath HS (without halogen) réticulée
  • Sheath HS (without halogen) réticulée for flexible cable
  • thermoplastic Sheath HS
  • thermoplastic Insulator HS
  • Lead
  • Armor strip iron or steel wire.

alloys

the almelec

Alloy of Aluminum with Magnesium and Silicon. It is mainly used for the realization of the air lines. Its resistivity (32,5 .   10  -9  Ω.m) is approximately the double of that of copper, but its mechanical characteristics enable him to resist the constraints related to the environment (Vent, Gel, Neige, variations of Température).

constantan

See also: Constantan

Alloy of Copper and Nickel of which the resistivity is almost independent of the temperature. It is used for the realization of some Capteur S of Température.

supraconductivity

bismuth

See also: Bismuth

This material with the characteristic to become Supraconducteur towards -200°C, which makes it interesting for a transmission of electrical energy while being cooled to the Hélium or the liquid Azote.

Applications

The electric wire is component still very largely used in the majority of the applications in the fields of electricity, electronics, electrical engineering. It is in particular the constituent main thing of certain prototype electronic charts (technology of wrapping).

It tends to be competed with by technologies " without fil" : telecommunications (telephony), data-processing networks (Wireless networking), Transmission of electrical energy without wire (short and long distances).

See too

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