Some more PQ test standards you might need to apply, to declare EMC compliance (Merely applying the 'relevant harmonised standards' is no longer sufficient)

23 Jun 2025

Keith Armstrong, www.cherryclough.com, 28 October 2021

Since the new EMC Directive came into force in 2016, we are very likely to find ourselves having to apply test standards that we are not used to, and which might not be ‘harmonised’ by being listed in the Official Journal of the EU (OJEU).

If you are still declaring EMC compliance by choosing the most relevant generic or product-family standards listed under the EMC Directive in the OJEU – then passing the tests they specify, and listing them on your Declarations of EMC Conformity – you are 5 years out of date and your products might suffer costly delays in EU and UK customs as a direct result.

Since the EMC  Directive 2014/30/EU (and the UK EMC Regulations) came into force in 2016, we have been required to perform, and document, an “adequate analysis and assessment of the risks” of our products’ complying with the Directive’s Essential Requirements.

The purpose of these “EMC risk assessments” is to specify the EMC standards, specifications, guidelines, etc., – or parts of them – to apply to our products to help ensure their EMC compliance in real life. 

Find out more about this (free) at: https://www.emcstandards.co.uk/the-new-eu-directives-which-came-into-force-in, or its (paid for) update https://www.emcstandards.co.uk/recent-emc-directives-2016.

This is especially true for issues of mains Power Quality (PQ), which are rather neglected by the generic and product-family EMC test standards. PQ problems are increasing, which creates more risks to the correct operation of our products and equipment.

Unfortunately, many seem to think that PQ is not an EMC issue at all – but clearly it is, because of the standards on immunity to PQ issues that have been published in the IEC’s 61000-x series of EMC test method standards.  

IEC 61000-4-27 tests for immunity to unbalance in three-phase mains supplies, and IEC 61000-4-28 tests for immunity to mains power frequency variations. I wrote guidebooks on both of these a few years ago, which you can read/download (free) at:
https://www.emcstandards.co.uk/a-practical-guide-for-en-61000-4-27-immunity-t
https://www.emcstandards.co.uk/a-practical-guide-for-en-61000-4-28-power-freq

These guidebooks include discussions on how these PQ issues arise, where they should be expected, and what they can affect, to help create EMC Risk Analyses. Both these standards have both been updated since I wrote these guides, but I expect the basics described in my guides to still be relevant and helpful.   

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