EMC tests on the way to market maturity
Published on 05/01/2025
The Importance of Pre-Compliance, Calibration, and Accreditation
Electromagnetic compatibility (EMC) is crucial for the market approval of electronic devices. From pre-compliance testing at the manufacturer’s site to final EMC testing in specialized labs, it must be ensured that the product does not cause interference and is protected from external influences. This article explains the importance of EMC testing, the role of accredited calibration laboratories, and the need for precise calibration to ensure reliable test results and compliance with international standards.
Whether consumer electronics, IT and telecommunications equipment, household appliances, or medical devices – they all undergo extensive testing before they are approved for sale. A key step in this process is EMC testing (Electromagnetic Compatibility), which ensures that a device does not generate unwanted electromagnetic interference and is immune to such interference. The final EMC test before market release is usually conducted in an accredited test laboratory, where compliance with the applicable standards and regulations is verified. Before that, a pre-compliance test is often carried out at the manufacturer's site, provided they have the necessary specialized facilities.
Pre-Compliance Testing: Early Problem Detection
Pre-compliance testing plays a vital role during product development, before the product is subjected to formal testing or certification. It allows potential problems to be identified and resolved early, ensuring that the device complies with the relevant EMC standards and regulations. The aim of this testing is early fault detection, cost reduction, and risk minimization by examining specific standards related to electrical safety and electromagnetic compatibility. Pre-compliance testing offers a cost-effective way to increase the likelihood that the product will pass the final compliance tests.
Pre-compliance testing not only helps to identify EMC issues early, but also contributes to product quality. However, the quality of these tests can only be guaranteed if the measurement equipment used is calibrated and the results are traceable. Traceability means that measurement results can be linked to an internationally recognized reference standard through an unbroken chain of calibrations — a key factor for the credibility of the results.
Calibration Traceability: Precision and Trust
Traceability of the calibration of the measuring equipment used is a vital aspect of EMC testing, as it ensures that the measurement results are based on international standards and can be verified.
It is essential that calibrations along the chain are documented and that the measurement uncertainty is stated for each calibration. The competence of calibration laboratories and their accreditation according to international standards such as ISO/IEC 17025 ensure that calibrations are carried out at a high level. An accredited lab must undergo regular audits to ensure that the methods used comply with current standards and that measurement procedures are accurate. Such auditing fosters trust in the lab and the measurement values it provides.
Traceability allows measurement results to be reproduced and compared, regardless of when and where they were taken. It is essential for demonstrating compliance with standards and regulations and ensuring quality assurance. Without traceability, EMC test results would not be reliable and could lead to incorrect assessments of electromagnetic compatibility.
Accredited Calibration Laboratories: The Foundation of Reliable Testing
An accredited calibration laboratory in Switzerland is a lab certified by the Swiss Accreditation Service (SAS). This certification confirms that the laboratory operates according to international standards, particularly ISO/IEC 17025, which defines the competence requirements for testing and calibration laboratories.
A major benefit of accredited calibration labs is the international recognition of calibration certificates. This is especially important in industries such as medical technology, aerospace, or pharmaceuticals, where compliance with international regulations and standards is crucial. Through the ILAC-MRA agreement, calibration results are recognized internationally, eliminating the need for additional testing during imports and exports and reducing technical trade barriers.
EMC Testing in the Chamber: The Final Verification
Following pre-compliance testing, the final EMC test is conducted by an accredited test lab. This testing is often carried out in specialized EMC chambers or anechoic rooms. There are two basic types of such chambers: “semi-anechoic chambers (SAC)” and “fully anechoic rooms (FAR).” These are designed to suppress reflections of electromagnetic signals, creating an environment free from external interference where only waves from the source can be measured. This setup allows precise measurement of EMC emissions and immunity of a device. The purpose of EMC chamber testing is to ensure that the electromagnetic emissions generated by the device remain within the permissible limits, while also confirming the device's immunity to external electromagnetic disturbances. This ensures the device operates reliably without affecting other devices.
To ensure accurate measurements, it is crucial that not only the measuring equipment but also the chamber itself is regularly calibrated. Devices such as spectrum analyzers, network analyzers, measuring receivers, as well as coupling/decoupling networks, attenuators, coaxial cables, or line impedance stabilization networks (LISN / AMN) must be calibrated regularly to ensure measurement values are trustworthy. Without regular calibration, test results could be flawed — sometimes without the responsible technician even noticing. This could result in devices being incorrectly classified as compliant or non-compliant, potentially leading to legal or safety consequences.
Knowledge Exchange and Continuous Education
The field of EMC quality assurance is highly complex and requires specialized expertise. Professionals who wish to learn more about the calibration of EMC test equipment can contact specialized calibration labs or join an EMC knowledge exchange group. Such groups, like the "EMC ERFA," offer opportunities to exchange ideas with other specialists and gain new insights. Topics such as computer simulations in the areas of EMC and cybersecurity (NIS), the application of new EMC standards, pre-compliance measures, or the retrofitting of heat pump systems are discussed and provide valuable practical input.
Are you interested in professional exchange or would you like to learn more about EMC ERFA? Feel free to contact Beat Schilbach (Beat.Schilbach@helbling.ch) or Patric Wickli (Patric.Wickli@aptomet.ch).
→ Download article as PDF-Datei
