Against the backdrop of global trade integration, Electromagnetic Compatibility (EMC) has become a "passport" for electrical and electronic products to access the international market. As a major global trade entity, the European Union adopted Directive 89/336/EEC (the EMC Directive) back in 1989 to harmonize EMC regulatory requirements among member states. Its objective was to eliminate trade barriers arising from divergent national standards and ensure the free movement of products within the EU market.
The directive underwent two revisions via 92/31/EEC and 93/68/EEC. The latest version currently in force is 2014/30/EU. Compared with earlier editions, its key revisions include: first, strengthened market surveillance and clear responsibilities for member states to trace and recall non-compliant products; second, simplified conformity assessment procedures, allowing enterprises to complete certification through self-declaration supported by third-party test reports; third, expanded coverage scope of applicable products, bringing emerging electronic devices such as smart wearables and IoT terminals under regulation.
Since 1 January 1996, the EU has formally mandated that all electrical and electronic products obtain EMC certification and bear the CE marking. This measure not only reshaped market access rules for the European electronics industry, but also fostered a global consensus on mandatory EMC administration. Major economies including the United States, Japan and China followed suit and established EMC regulatory systems tailored to their respective markets.
Essentially, Electromagnetic Compatibility (EMC) refers to the capability of equipment or systems to "coexist without mutual interference" in a complex electromagnetic environment, which can be divided into two core dimensions:
(1) Electromagnetic Interference (EMI): Outgoing interference emitted by equipment
It denotes unwanted electromagnetic signals generated during equipment operation, which may disrupt the normal operation of other devices. According to transmission paths, it is categorized as follows:
Conducted Emission (CE): Electromagnetic interference propagating through conductors such as power cables and signal wires, e.g., transient pulses released into the power grid via power cords when a refrigerator starts up.
Radiated Emission (RE): Electromagnetic interference transmitted in the form of spatial electromagnetic waves. For instance, electromagnetic waves radiated by a working microwave oven may interfere with nearby wireless walkie-talkies.
(2) Electromagnetic Susceptibility (EMS): Equipment immunity against external interference
It refers to the capacity of equipment to maintain proper functionality when exposed to external electromagnetic interference. Based on interference sources, it includes:
Conducted Susceptibility (CS): Immunity to electromagnetic interference transmitted via conductors, such as the ability of industrial machine tools to withstand grid voltage fluctuations.
Radiated Susceptibility (RS): Immunity to spatial electromagnetic wave interference, for example, the capability of an automotive navigator to deliver accurate positioning near mobile phone signals.
Electrostatic Discharge (ESD) Immunity: Capacity to resist electrostatic discharge interference, e.g., the performance of a computer host that avoids crashing upon human contact.
Electrical Fast Transient / Burst (EFT/Burst) Immunity: Ability to withstand sudden high-frequency pulse interference in circuits, commonly tested during relay switching operations.
Power Frequency Magnetic Field (PFMF) Immunity: Resistance to power frequency (50Hz/60Hz) magnetic field interference, such as stable operation of medical equipment near transformers.
