What is the purpose of a Faraday cage in electrical systems, and how does it function?

The purpose of a Faraday cage in electrical systems is to shield the enclosed space from external electromagnetic fields. A Faraday cage is an enclosure formed by a conductive material, such as metal mesh or solid metal sheet. Its function is based on the principle that when an external electromagnetic field impinges on the conductive material, it causes the free electrons within the conductor to redistribute themselves. This redistribution of electrons creates an opposing electromagnetic field that cancels out the external field within the enclosure. In essence, the Faraday cage prevents external electromagnetic radiation from penetrating the enclosed space and protects sensitive electronic equipment from interference, noise, or damage. How it works: When an external electric field is applied, the free electrons in the conductive material move to counteract the field. This creates a surface charge distribution that cancels the electric field inside the cage. For electromagnetic waves, the changing magnetic field induces circulating electric currents in the cage material. These currents generate their own electromagnetic field that opposes the incident field, preventing it from entering the enclosure. The effectiveness of a Faraday cage depends on the conductivity of the material, the size and shape of the enclosure, and the frequency of the electromagnetic radiation. The higher the conductivity and the smaller the openings in the cage, the better the shielding effectiveness. For example, a metal enclosure around sensitive electronic control equipment in a plant acts as a Faraday cage, protecting the equipment from electromagnetic interference from nearby motors, radio transmitters, or other sources of electromagnetic radiation.