Skin Effect And Proximity Effect

Contents

Skin Effect

Unlike direct current (DC), where the current distribution is uniform throughout the entire cross-section of the conductor, the current density is non-uniform for AC supply.

The degree of non-uniformity depends on the frequency of supply.

This effect is known as the skin effect as the current density increases near the surface
or the skin of the conductor due to magnetic flux having set up by the alternating currents inside the conductor.

The skin depth is inversely proportional to the square of the supply frequency. In that way, the effective AC resistance of the conductor increases from its DC value.

Proximity Effect

When two or more conductors carrying alternating current are placed side by side, the magnetic flux created by one conductor sets up a circulating current and the corresponding
flux in other conductor, affecting the current density or the uniformity of current distribution.

Thus, the effective resistance of the conductor changes due to supply of the current in other conductor.

This effect is known as proximity effect.