6.6.1 Definition

Shielding, in a broad sense, refers to protecting electronic equipment from electromagnetic interference. This can affect the equipment due to electromagnetic radiation, or it can be conductor-based, in which case transmission from one conductor to another susceptible to interference may occur due to capacitive or inductive coupling. Since the frequency range of electromagnetic interference in industrial environments is very wide, from about 10 kHz for contactors, switching regulators, etc., to 3 GHz for mobile phones, and the different mechanisms of interference transmission largely depend on frequency, it is difficult to predict which transmission path dominates in the respective application and which shielding measures will be most effective.