Skin effect is a phenomenon that occurs in AC power lines and leads to a decrease in current density in the center of the wire and an increase in the outer layers or shell of the wire. When alternating current passes through a wire, a magnetic field is created around the wire. By changing the direction of the alternating current, the direction of the created field also changes. At this time, according to the lens law, a current is created in the opposite direction of the normal current in the wire to oppose the change of field. The current generated in the central layers of the wire is more and in the outer layers is less. In such a way that sometimes the net current in the center of the wire is equal to zero and is more concentrated in the outer layers or shell. This is why it is called the Skin Effect.
The skin effect causes a non-uniformity of current density in the wire cross section. The higher the frequency of the current, the more the skin effect is manifested and the more frequent and opposite currents are created in the center of the wire. For this reason, the skin effect at high frequencies leads to increased resistance to current passage.
To reduce the skin effect on transmission lines, bundling or grouping of lines is used. In such a way that instead of one transmission line, several lines are used to transfer the same energy.
