EMI: Electromagnetic Interference

Electromagnetic Interference (EMI) is a term used to designate interference in a electrical device or cable caused by another electrical device or cable.

Electromagnetic Interference (EMI) is a problem that exists in all electrical systems and cables because all electrical devices and cables eminate electromagnetic waves. The waves may interfere with the proper operation of nearby electronic devices or the proper transmission of signals in nearby cabling systems. Electromechanical devices, such as a washing machine, tend to emit low-frequency waves, while computers and other electronic devices with integrated circuits tend to emit high-frequency waves. If the emissions have sufficient energy and are close enough to another device, they will interfere with that device.

If not controlled properly, the interference can affect the normal operation of other devices, or even destroy them. The issue of compatibility among electrical devices in a system or common environment has evolved into an engineering discipline, Electromagnetic Compatibility, or EMC.