Vortex currents are considered as one of the most surprising phenomena which are found in electrical equipment. It is amazing that the mankind learned to use negative aspects of action of vortex currents for the good.
History of opening of vortex currents
In 1824 the French physicist Daniel Arago for the first time observed action of vortex currents on the copper disk located under a magnetic needle on one axis. At rotation of an arrow in a disk vortex currents were directed, setting it in motion. This phenomenon received the name of "Arago's effect" in honor of his pioneer.
Researches of vortex currents were continued by the French physicist Jean Foucault. He in detail described their nature and the principle of action and also observed the phenomenon of heating of the conducting ferromagnetic rotated in static magnetic field. Currents of the new nature were called in honor of the researcher too.
Nature of vortex currents
Foucault's currents can take place at impact on the conductor of variation magnetic field, or when moving the conductor in static magnetic field. The nature of vortex currents is similar induction which arise in linear wires when passing through them electric current. The direction of vortex currents is closed around and force which is opposite causing them.
Foucault's currents in economic activity of the person
The simplest example of manifestation of currents of Foucault in ordinary life - their impact on a magnetic conductor of the obmotochny transformer. Because of influence of the induced currents there is a low-frequency vibration (the transformer hoots) promoting strong heating. In this case energy is wasted, and the efficiency of installation falls. For prevention of considerable losses the cores of transformers do not produce integral, and gather from thin strips of electrotechnical steel with low specific conductivity. Strips are isolated among themselves by electrotechnical varnish or a layer of scale. Emergence of ferrite elements allowed to carry out small-sized magnetic conductors integral. The effect of action of vortex currents is used everywhere in the industry and mechanical engineering. Trains on a magnetic pendant use Foucault's currents for braking, high-precision devices shooters, based on action of vortex currents have the system of damping specifying. In metallurgy the induction furnaces having the whole complex of advantages before similar installations are widespread. In the induction furnace the heated metal can be placed in a vacuum, trying to obtain its full decontamination. Induction melting of ferrous metals also became widespread in metallurgy in view of high profitability of installations.