EMC Compliance Guide

• EMC Fundamentals: Explains EMC as the combination of controlled emissions and adequate immunity, and defines disturbance, interference, and susceptibility.

• EMC Emissions: Covers conducted and radiated emissions. The applicable standard defines ports, frequency ranges, measurement methods, and limits.

• EMC Immunity: Introduces common immunity phenomena such as ESD, surge, burst, and RF disturbances. Product standards determine the required tests, levels, and performance criteria.

• EMC Test Procedure: Describes test equipment and the workflow from requirement selection to reporting.

• EMC Compliance for Global Markets: Shows how requirements differ by product and market, with examples for the EU, US, Canada, Japan, South Korea, and China.

Electromagnetic Compatibility (EMC) describes the ability of electrical and electronic equipment to operate as intended in its electromagnetic environment without introducing intolerable electromagnetic disturbances into that environment.

EMC combines two complementary aspects:

• Emissions: electromagnetic disturbances generated by equipment and transferred through cables or radiated into the surrounding environment

• Immunity: the ability of equipment to maintain the required performance when exposed to electromagnetic disturbances

When a disturbance degrades the performance of equipment, the effect is called electromagnetic interference (EMI). Electromagnetic susceptibility describes how readily equipment is affected; higher immunity therefore corresponds to lower susceptibility.

EMC emissions are electromagnetic disturbances generated by electronic equipment during operation. They may be transferred through cables as conducted emissions or radiated from enclosures, cables, and circuitry as radiated emissions.

Primary emission paths:

• Conducted emissions: disturbances transferred along power, signal, or communication lines

• Radiated emissions: electromagnetic energy emitted into the surrounding environment

The applicable product, product-family, or generic standard defines the relevant ports, frequency ranges, measurement methods, and limits.

Electromagnetic disturbances can be generated by equipment or arise in the surrounding environment. Knowing these sources helps identify design vulnerabilities and plan pre-compliance testing.

Typical disturbance sources include:

• Switching power supplies: generate harmonics and broadband electromagnetic disturbances due to high-frequency switching.

• Digital circuits: clock harmonics and fast switching edges from processors, memory interfaces, and high-speed data lines.

• Cables and wiring harnesses: act as unintended antennas that radiate or couple disturbances, particularly when inadequately shielded or poorly routed.

• Motors, relays, and inductive loads: arcing and contact bouncing that cause broadband electromagnetic disturbances.

• Industrial equipment: welding systems, inverters, and heavy machinery producing strong broadband disturbances in industrial environments.

• Lighting systems: emissions from fluorescent lamps, LED drivers, and electronic ballast circuits.

• RF transmitters: intentional radiators such as mobile phones, Wi-Fi, Bluetooth, and other wireless systems operating nearby.

• Natural and electrostatic phenomena: lightning, electrostatic discharge, and geomagnetic disturbances that may affect equipment.

Recognizing these disturbance sources during the design phase supports targeted mitigation.

Electromagnetic immunity is the ability of equipment to maintain the required performance when exposed to electromagnetic disturbances. Electromagnetic susceptibility describes how readily equipment is affected by those disturbances. Higher immunity means lower susceptibility.

Common EMC Immunity Tests

• Electrostatic Discharge (ESD): sudden transfers of static electricity

• Electrical Fast Transients (Burst): rapid voltage spikes coupled to power or signal lines

• Surge: overvoltage events associated with switching operations or lightning

• Radiated RF Immunity: exposure to radio-frequency electromagnetic fields

• Conducted RF Immunity: radio-frequency disturbances coupled into cables

The applicable product or product-family standard determines which tests apply and specifies the ports, operating modes, frequency ranges, test levels, and performance criteria.

Equipment connected to a public low-voltage network may also have to meet limits for harmonic currents and voltage fluctuations.

• Harmonic currents (EN 61000-3-2): limits the harmonic currents drawn by equipment with a rated input current up to and including 16 A per phase.

• Voltage fluctuations and flicker (EN 61000-3-3): limits voltage changes and flicker caused by equipment up to 16 A per phase that is not subject to conditional connection, on public 220–250 V, 50 Hz low-voltage systems.

Where these standards apply, the results form part of the technical evidence for the conformity assessment and CE marking.

A structured EMC test procedure supports consistent, reproducible evaluation against the requirements that apply to the product and target market.

Test Equipment and Environments

EMC assessments use specialized instruments and controlled test environments selected for the relevant emission or immunity method, such as:

• Spectrum analyzers and EMI receivers: measurement of unwanted emissions across defined frequency ranges

• Signal generators: generation of controlled electromagnetic disturbances for immunity tests

• Anechoic and semi-anechoic chambers: shielded environments for radiated emission and immunity measurements

• Line Impedance Stabilization Networks (LISNs): defined impedance and conducted-emission measurement on AC or DC lines

• Coupling/decoupling networks (CDNs): coupling of RF disturbances into cables for conducted-immunity tests

The CISPR 16 series specifies radio-disturbance measuring apparatus and methods used for emission measurements. Immunity setups follow the relevant basic test method, such as the EN 61000-4 series, together with the applicable product or product-family standard.

Pre-compliance evaluations complement design activities by identifying potential EMC issues before formal laboratory testing. Early assessments help reduce redesign cycles and development cost.

Learn more about our EMC pre-compliance testing services.

Electromagnetic compatibility requirements depend on the product, its intended use and installation, and the target market.

In the European Union, the applicable framework depends on the product and sector:

• Radio equipment covered by the RED: assessed under the RED (2014/53/EU), which contains its own EMC requirement.

• Other electrical and electronic equipment: assessed under the EMCD (2014/30/EU) where the equipment falls within the directive's scope. Sector-specific legislation can apply instead or add requirements.

To identify the requirements for a product, start with its functions, intended use, and target markets. Then determine the applicable standards and conformity assessment route.

Outside the EU, authorities use product- and procedure-specific systems. Emissions, immunity, documentation, equipment authorization, and laboratory-recognition requirements apply in different combinations. The tables below show selected examples.