What is the skin effect and where it is used in practice

Perhaps you ever heard such a phrase as "skin effect". Do you know what it is, if not, then you are just the right place. In this article I will tell you what it is and where it is used this effect in practice.

What is the skin effect

To begin, let's define this effect. Thus, the skin effect - is the amplitude reduction effect of electromagnetic waves depending on the degree of their penetration into the conductor medium. Bit technical and confusing sounds, but now explain.

So, simply put, is such an effect, in which an alternating current electric charges under the action of electromagnetic phenomena inside conductor are displaced to its surface.

In this process, the flowing current is inhomogeneous structure in the central part of the charge density of the conductor is lower than on its periphery.

In this case, the current penetration depth can be found in this expression:

Applying this formula can be found that for a copper conductor with a frequency of 50 Hertz current penetration depth is approximately equal to 9.32 mm. This means that if the copper conductor cross-section will be more than 9.32 mm, in the central part of the current will be absent.

And here is the following statement is true: the more importance will be the frequency, the shallower will penetrate current. And if the frequency will increase twice, the penetration depth of the fall in the square root of two. Increasing the frequency of 10 times would reduce the penetration depth of the root of 10 times.

As current is distributed

Looking at the above image, you can clearly see the distribution of current in the conductor of circular cross section. Beyond the borders of the penetration depth of the current movement is either missing completely or is so small as to be negligible.

And if the central portion of the conductor where there is no current flow, just simply remove, then we would get a hollow conductor and the conductive characteristics remain the same. Resistance will be the same, the only change inductive and capacitive component of the conductor.

It turns out that the resistance of the conductor in the electrical circuit is dependent not only on the conductor material, but also on what frequency current passes through it. And at significant frequency values ​​substantially all of the current will flow along the outer boundary of the conductor in the contacting zone with its external environment.

Practical use of the skin effect

This gradation current density depending on its frequency enables one and the same conductor to perform transmission of electric signals of various frequencies.

And the high-frequency signals are transmitted through the outer radius of the conductor, and the low-frequency on the inner radius.

For example, according to this principle is implemented in the high-frequency PJSC "Rosset", where high-voltage wires transmitted not only current with a frequency of 50 Hertz, but also carried out between the telephone duty substations and dispatchers.

Just knowing the maximum possible current penetration depth of copper wire, there is no reason to make a monolithic core larger cross-section. If required conductor with a large cross section, it is advisable to apply the core wire.

It is because of the skin effect, you will not find a copper conductor with a monolithic residential section of more than 10 mm2.

As the skin effect is widely used in induction melting furnaces, where due to the current high frequency concentrated in the outer shell conductor and the further heating occurs meltdown metal.

That's all I wanted to tell you about the skin effect and how it is used in practice. If the article was useful to you, you will appreciate her huskies and thank you for your attention!