Eddy current - eddy currents, what it is and where they are used

Vortex or even so-called cyclical currents may carry in addition to the harm also benefit. On the one hand, the eddy currents - this is the immediate cause of energy losses in the conductor or the coil. At the same time this effect built modern induction furnace, so that the benefits of such currents is. Let's talk about the benefits and harm of a little more detail.

brief definition

To begin, let's define voiced phenomenon. Eddy currents - these currents which start to flow due to exposure to an alternating magnetic field. This may not change the field itself and the position of the conductor in the field, that is if the conductor moves to the static field, the eddy currents therein are produced all the same.

And the flow path of these currents can be determined. It is only known that the current flows at the location where the minimum resistance.

As revealed this phenomenon

Initially, the eddy currents were recorded in 1824, scientists
YES. Arago during the following test:

On one axle copper disc and the magnetic needle had been installed, the disc was placed at the bottom, and the arrow is slightly higher. So, when the arrow is rotated, the copper disc and began to rotate, as the flowing currents formed a magnetic field which interacts with the magnetic needle.

The observed effect is called - Arago phenomenon.

After a few years, this issue has become a study Maxwell FaradayWho just discovered the law of electromagnetic induction. So, according to the public law, it was assumed that the magnetic field has a direct impact on the atomic lattice of the conductor.

And formed as a result of exposure to an electric current, always generates a magnetic field around the conductor.

A detailed description of the eddy currents have experimenter FoucaultThis is why the second name of eddy currents - eddy currents. With a history of little acquainted, let's find out the nature of the eddy currents.

Nature eddy currents

Closed circular currents in the conductor can be formed only in the version when the magnetic field, in which is a conductor, has an unstable structure, i.e., it has the rotation or change with time.

It follows that the strength of the eddy currents has a direct relationship with the rate of change of magnetic flux passing through the conductor.

According to generally accepted theory of electrons in a conductor are moved in a linear manner due to the potential difference, and this means that the current has the reverse direction.

Eddy currents behave quite differently and form a vortex closed loop directly in Windows Explorer. The data currents capable of interaction with a magnetic field that created them.

Through the study of these currents, the scientist Lenz It concluded that the eddy currents generated by the magnetic field does not allow a magnetic flux, which created these currents change. In this case, the eddy current direction of the field lines is identical to the vector direction of the induced current.

Eddy currents and damage

Let us remember, looks like a conventional transformer.

So, if you look closely at the core, you will see that it is made up of individual plates. Do not you think that it was much easier to execute one piece?

It is in this "fragmentation" are trying to minimize the negative impact of eddy currents. Because eddy currents heat the body in which they occur.

How do they appear in the transformer? His work and is based on the principles of interaction of the magnetic fields of variable nature, and as we already know alternating field inevitably generates eddy currents.

It turns out that the eddy current heats the core. A heating leads to a decrease in efficiency and a strong overheating lead to melting of the insulation, and hence degradation of the transformer.

How to reduce the loss

These losses can be described by the following formula:

As you know, the following is true: a conductor with a small cross-section has a high resistance, and the greater the resistance of the conductor, the less current passes through it.

That is why the core is made of a single piece of steel, and not assembled from thin plates which are insulated from each other dross or lacquer layer. This method of assembly minimizes core losses in the core, i.e. reduce eddy currents to a minimum.

Useful use of eddy currents

These currents are not only negative. They long ago learned to good use. For example, the properties of the eddy current used in induction counters. These currents retard the aluminum disk rotation, which is rotated by the magnetic field.

Thus, the creation of induction furnaces had incommensurable contribution to the development of the whole of modern industry began production.

These furnaces operate as follows: the metal which will be subjected to melting, is placed inside a coil through which the current starts to pass higher frequency. The magnetic field generates large currents within the metal, and then heating to melt the metal.

In apartment buildings, you can see Induction cooker, the principle of which is also based on the effect of the formation of eddy currents.

conclusion

That's all I wanted to tell you about the eddy currents (Foucault currents). If the article was useful to you, or are interested in, you will appreciate it Like. Thank you for your attention!