Why selecting the right power supply is crucial to EMC Testing Results

Most of our customers must comply with the EMC Directive 2014/30/EU prior to application of a CE marking to their products. This is because the EMC Directive is applicable to almost everything with active electronics. Unlike North American EMC compliance (FCC and ICES) which requires emissions compliance only, EU compliance to the EMC Directive requires emissions and immunity testing.

Proving this in most cases means testing to one or a pair of harmonized EN standards for EMC. These harmonized standards indicate the required tests – which are usually contained in other standards we call “test standards”. The most frequently used EMC test standards are below.

  • EN 61000-4-2 – ESD Immunity
  • EN 610004-3 – Radiated Immunity
  • EN 61000-4-4 – EFT Immunity
  • EN 61000-4-5 – Surge Immunity
  • EN 61000-4-6 – Conducted Immunity
  • EN 61000-4-8 – Magnetic Fields Immunity
  • EN 61000-4-11 – Voltage Dips/Interrupts
  • EN 55011 – Radiated and Conducted Emissions
  • EN 61000-3-2 – Harmonic Current Emissions
  • EN 61000-3-3 Flicker/Voltage Fluctuations Emissions

Now we come to the purpose of this article: power supplies and the problems that can be created for your compliance project if you select one that is not suitably approved. We frequently see documentation for power supplies that does not prove compliance. These power supplies can be the source of EMC testing failures in our chamber because power supplies can cause emission issues. And non-compliant power supplies cause more issues than compliant power supplies.

The documentation for a power supply may look, on its face, like the product is compliant but a little investigative work often shows that it is not. Keep in mind that anyone can place a CE marking on a product. Actually complying with the requirements is different. Because of this we suggest asking for the test report or reports from the manufacturer.

We have seen many reports that were generated by a manufacturer internally. In the world of compliance these are not valid. Why? To be an actual test report the testing lab must have laboratory accreditation and the gear used to test the products must be continually calibrated. That gear and the calibration dates must be listed in the report. The testing standard must also be listed in the report.

Our sales department can discuss these issues with you. In fact, our salespeople look at these documents so frequently that we can often immediately tell you if a test report or declaration of conformity appears valid.

I hope this helps. Please contact us today with any questions or to discuss your project.


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