Both IEC 61000-6-4 and IEC 618000-3, Category 3 relate to Industrial use with supplies not connected to the public low voltage mains. The limits for 61800-3 Cat 3 are higher than those for 61000-6-4, so which should I use for my control panel?

18 Jan 2021

Author: Keith Armstrong

Both IEC 61000-6-4 and IEC 618000-3, Category 3 relate to Industrial use with supplies not connected to the public low voltage mains. The limits for 61800-3 Cat 3 are higher than those for 61000-6-4, so which should I use for my control panel which houses variable speed drives?

There is no point in looking for any consistency between IEC 61000-6-4 and IEC 61800-3, because they were created by very different teams with very different goals.

61000-6-4 was created by the team who created all of the original four ‘generic’ EMC standards (-6-1, -2, -3, and -4), and the team members covering a very wide range of applications.

However, 61800-3 was created by an IEC team specifically set up by motor drive manufacturers who were only interested in their own applications.

Far be it for me to impugn the intentions of the 61800-3 team, but it is worth noting that the European Association of Competent Bodies (as it was then), the EACB, complained to the European Commission about them adopting this standard (and also IEC 61131-2 on Programmable Logic Controllers) under the EMC Directive. The EACB argued that both were unsuitable standards because they did not control certain EM phenomena in a way that was consistent with the four generics (the IEC 61000-6-x series) and so could not ensure compliance with the Essential Legal Requirements of the EMC Directive. 

Up until that time, if they had been asked to do so, the European Commission had been automatically adopting EMC standards created by IEC teams, under the EMC Directive.

When they received the complaint from the EACB, the European Commission said it would not revoke IEC 61800-3 or IEC 61131-2, but would in future employ an EMC Consultant whose job was to check whether standards created with the aim of being adopted under the EMCD were actually suitable for adoption. They were as good as their word and did employ an EMC consultant for this purpose. As a result, some IEC standards have been prevented from being adopted under the EMC Directive.

The upshot is – if your product/equipment/system falls within the scope of IEC 61800-3 you may choose to apply it, and (for higher-powered drives) probably save money compared with if you had applied IEC 61000-6-2 (immunity) and -6-4 (emissions).  But 61800-3 is flawed, and I (and others) see a lot of larger motor drive installations that have big EMC problems, that are very costly to fix.

But it is very important to understand that since the new EMC Directive 2014/30/EU came into effect in 2016, it is no longer sufficient to claim EMC Compliance based on merely passing a test to the most relevant standard listed under the EMC Directive in the Official Journal of the EU! 

Manufacturers/suppliers/system integrators/etc. are now legally required to perform an assessment of the risks that their product/equipment/system will fail to comply with all of the EMC Directive’s “Essential Requirements” (crudely: not to cause or suffer EMI when used as intended) – and then apply whatever standards, guides, codes of practice, or just good EM engineering are needed to adequately cover each of the risks they have identified.   

I am fairly confident that a correct and competent application of these new-ish legal requirements would find that, where high-power motor drives were involved, some of the risks of failing to comply would need to apply tests used by the generics (IEC 61000-6-x series), rather than those in IEC 61800-3.

Unfortunately, those who rely entirely on EMC Test Labs rather than developing their own EMC competence, are often still unaware of the new compliance requirements in 2014/30/EU.

This is because EMC test labs exist to do tests, so they tend to ignore everything else. They usually don’t (in my experience) try to educate their customers about the fact that EMC compliance now needs more than just testing.

And why should they? Its not their responsibility, after all, because (despite the claims of some test labs) there is no such thing as “CE Approval”, and never has been.

Manufacturers/suppliers/system integrators/etc. are entirely – and only – responsible for deciding whether they should affix the CE Marking to the products/equipment/systems they make available on the EU’s Single market (and – for now – on the UK market).  No EMC Test Lab, Competent Body, or Notified Body can ever legally do this, no matter what they try to tell you.

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