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Electro-Magnetic Compatibility(EMC)is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy which may cause unwanted effects such as Electro-Magnetic Interference (EMI) or even physical damage in operational equipment.

The goal of EMC is the correct operation of different equipment in a common electro-magnetic environment. It is also the name given to the associated branch of electrical engineering.

EMC pursues three main classes of issue:

  • Emission is the generation of electro-magnetic energy, whether deliberate or accidental, by some source and its release into the environment. EMC studies the unwanted emissions and the countermeasures which may be taken in order to reduce unwanted emissions.
  • Susceptibility is the tendency of electrical equipment, referred to as the "victim", to malfunction or break down in the presence of unwanted emissions, which are known as Radio Frequency Interference (RFI).
  • Coupling is the mechanism by which emitted interference reaches the "victim".

Interference mitigation and hence electro-magnetic compatibility may be achieved by addressing any or all of these issues, i.e., quieting the sources of interference, inhibiting coupling paths and/or hardening the potential victims.

In practice, many of the engineering techniques used, such as grounding and shielding, apply to all three issues.

Warning sign for Electro-Magnetic Interference.