EMC (electromagnetic compatibility) is the concept of enabling different electronics devices to operate without mutual interference – electromagnetic interference ( EMI) – when they are operated in close proximity to each other.
The aim of employing EMC measures is to ensure that a variety of different items of electronics equipment can operate in close proximity without causing any undue interference.
There are two main elements to EMC:
- Emissions: The EMI emissions refer to the generation of unwanted electromagnetic energy. These need to be reduced below certain acceptable limits to ensure they do not cause any disruption to other equipment.
- Susceptibility & immunity: The susceptibility of an item of electronics to EMI is the way it reacts to unwanted electromagnetic energy. The aim of the design of the circuit is to ensure a sufficiently high level of immunity to these unwanted signals.
Electromagnetic interference is the name given to the unwanted electromagnetic radiation that causes potential interference to other items of electronics equipment.
There are many ways in which electromagnetic interference can be carried from one item of equipment to another. Understanding these methods is a key to mitigating the effects of the electromagnetic interference.
EMI can be divided into two categories:
- Continuous interference: The continuous interference is often in the form of a radio signal or oscillation that is maintained. It could be from an unscreened oscillator, or it may be in the form of wideband noise.
- Impulse interference: This form of interference consists of a short impulse. It may arise from an electrostatic discharge, lightning, or a circuit being switched.
Apart from understanding the form of the interference, it is also necessary to know how the interference is traveling from the transmitting device to the receiving device. Unfortunately this is not always easy to discover as many of the paths are difficult to define. However good initial design alleviates many problems.
Want to learn more? Tonex offers courses in EMI/EMC where participants learn technical overviews of many EMI/EMC topics. Tonex Applied EMI/EMC courses are applicable to professional engineers and technicians practicing in EMC fields such as bonding, grounding, shielding, EMI prediction, EMI analysis, conducted and radiated interference, lightning protection and more.
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