Electromagnet

General information

A electromagnet is an electrotechnical body producing a Magnetic field when it is fed in electricity. It consists of a winding and often of ferromagnetic a material part soft called magnetic circuit . When the winding is traversed by a running, it creates a Magnetic field channeled by the magnetic circuit. When the electromagnet is supplied by Alternative course, the magnetic circuit must be made up of fine plates of Fer soft assemblies in layers, in order to avoid losses related to the appearance of Eddy current in his sein.
The form given to the magnetic circuit allows, either to concentrate the effect of the magnetic field, or of the canaliser.

The electromagnet plays the part of a Aimant ordered by an electric current. It is used either to produce a electromagnetic Force, or to produce a magnetic field controlled in an area of space.

Remark : When the electromagnet is subjected to a variable magnetic field , it is the seat of a electromotive Force.

Applications

The electromagnet often forms part of an electric unit (generating electrical motor, , radio, Télévision, Magnétophone, Magnétoscope, Hard drive, Electron microscope, various machines). In the engines and the generators, it is used to create a electromagnetic Champ which one can control, case of the inductive or, a collector of Electric current, case of the induced .

Solo applications

When it is used only the electromagnet can be comparable with a ordered magnet.
  • the electric trowel of a door: the electromagnet when it is fed, car the latch blocking the lock, thus releasing the door which can be open without key nor handle.

  • the electromagnetic relays, the Circuit breaker S, the Télérupteur S are based on the attraction of a ferromagnetic mass by an electromagnet. This mass starts displacements of the electrical contacts.

  • the lifting of metal masses as well as the sorting of metal waste is entrusted to large electromagnets

  • the Injecteur S of Carburant (gasoline and Gas oil) of the engines assembled in the current cars are electromagnets controlled directly by the electronic Calculateur of management of the Moteur. When the calculator wants to inject fuel, it provides an electric current to the injector, the needle stopping the grout hole moves back thus letting enter the fuel under pressure the engine. The needle is positioned back by a Ressort to the disappearance of the current.

  • In the tape recorders (Tape recorder, Video tape recorder, magnetic track), the electromagnet is used for to magnetize the metal particles of the data carrier. While the magnetic medium (tape or disc) ravels in front of a magnetic head at a controlled speed, an electric current (image) of the source to record master key in the head thus transferring the Information in form magnétique.
    For the reading, the support ravels again in front of the magnetic head, in which the variations of Magnetic field induce a Electric current, which is amplified and adapted to be restored in its original form.

  • In the sound reproduction, the electromagnet is the engine of the loudspeakers: a membrane is put moving by a reel plunged in the magnetic field of a permanent magnet. The membrane vibrates at the rate/rhythm of the signal feeding the bobine.

  • In many electromechanical automatisms, much of relatively short linear movements (less than 5 centimetres) is actuated by devices with plunger core, particular application of the electromagnet.

  • Certains lockings of doors is entrusted to electromagnets whose attraction force can reach 6000 NR. comparable devices maintain the open doors in certain buildings, to release them in the event of fire.

See also: Loudspeaker

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External bonds

  • Calamit Various types of electromagnets

  • Electromagnets of the contactors

Simple: Electromagnet

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