EMC Certification: Dual Compliance with EMI and EMS
EMC (Electromagnetic Compatibility) certification for power equipment encompasses two main areas: EMI (Electromagnetic Interference emission limits) and EMS (Electromagnetic Susceptibility/Immunity requirements). Applicable standards include the GB/T 7251 series and the EMC requirements associated with IEC 61439 (emissions per GB 4824/CISPR 11; immunity per the IEC 61000 series).
Industry experts note that the core of EMC certification lies in two-way verification: the equipment must neither interfere with other devices (meeting emission standards) nor be susceptible to external interference (meeting immunity standards).
The EMC test report is a component of CE certification (under the EMC Directive).
Two Key EMC Requirements
- EMI Emission Limits: Conducted and radiated disturbances tested against GB 4824/CISPR 11 limits (Class A/B);
- EMS Immunity: Testing for Electrostatic Discharge (ESD), Radiated Susceptibility (RS), Electrical Fast Transient (EFT), Surge, Power Frequency Magnetic Field (PFMF), etc., per the IEC 61000 series;
- Power Terminal Disturbance: Conducted emissions tested against standard limits;
- Test Environment: Shielded rooms and Open Area Test Sites (OATS), with testing configured according to standards.
Key Points of EMC Certification
First, standard alignment.
EMC standards are matched to product types and voltage levels (e.g., low-voltage switchgear assemblies follow the EMC requirements associated with IEC 61439).
Second, design anticipation.
EMI is controlled through filter, shielding, and grounding designs, while pre-testing helps minimize the need for rework.
Third, testing agencies.
Commission qualified laboratories for testing, and use the resulting reports for CE certification.
Fourth, report alignment.
Ensure the model and configuration in the EMC report match the actual product (as component changes can affect EMC performance).
Pitfalls to Avoid
First, “missing EMC tests.”
Incomplete EMC testing leads to incomplete CE certification.
Second, “configuration mismatch.”
The report corresponds to a different configuration;
changes to components like variable frequency drives (VFDs) can invalidate EMC compliance.
Third, “poor grounding.”
Inadequate grounding and shielding designs result in failure to meet immunity standards.
Trends and Reminders
EMC requirements are becoming stricter as equipment becomes more intelligent; the increased use of VFDs and smart modules necessitates higher standards for EMC design and testing.
For exporters, the recommendation is to ensure “dual compliance” (meeting both domestic and destination market standards), anticipate EMC needs during the design phase, and ensure reports accurately reflect the product configuration.
EMC is essentially a pact of compatibility—ensuring the device neither causes interference to others nor is susceptible to interference itself.
