The role of shielding wire in cable

Jan. 13, 2025

Shielded wire is a kind of wire with a metal braided outer shell specially used to reduce the influence of external electromagnetic fields on power supply or communication lines. This shielded wire also prevents the line from radiating electromagnetic energy outward. The shielding layer needs to be grounded, and external interference signals can be introduced into the earth by this layer. The shielding layer of the shielded cable is mainly made of non-magnetic materials such as copper and aluminum, and the thickness is very thin, which is much smaller than the skin depth of the metal material at the frequency of use (the so-called skin effect refers to the distribution of current in the conductor cross section tending to the conductor surface with the increase of frequency. The higher the frequency, the smaller the skin depth, that is, the higher the frequency, the weaker the penetration ability of electromagnetic waves). The effect of the shielding layer is not mainly due to the reflection and absorption of the electric field and magnetic field by the metal body itself, but due to the grounding of the shielding layer. Different grounding forms will directly affect the shielding effect.