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Home > News > Company News > Times change so EMC tests must.....

Times change so EMC tests must follow

  • Author:Ella Cai
  • Release on:2017-06-14
An electromagnetic compatibility (EMC) emissions standard has replaced standards that the industry has been working with for decades.

In an attempt to make EMC emissions specification selection easier when testing equipment, compliance with EN 55032:2012 (Electromagnetic compatibility of multimedia equipment – emission requirements) became mandatory in March 2017. This standard has become effective as a harmonised emission standard in compliance with EMC Directive 2014/30/EU. The old EN 55022 standard will no longer be accepted, and therefore cannot be used to presume conformity to the EMC directive.

It is important to emphasise that this standard does not cover intentional transmissions from radio transmitters, which must now fully comply (as of 13 June 2017) with the new European Union Radio Equipment Directive (RED) 2014/53/EU. The RED is applicable to all non-military electrical and electronic devices that intentionally emit and receive radio waves at frequencies below 3,000GHz. Also, the introduction of the RED sees satellite, TV and radio receivers fall within the scope of a ‘radio’ directive for the first time, as previously such products were required to comply with the EMC directive.

EN 55032 applies to multimedia equipment that has a rated RMS AC or DC supply voltage not exceeding 600V. It incorporates three old standards into one – EN 55022: 2010 AC: 2011 (information technology equipment), EN 55013: 2013 (sound and television broadcast receivers, and associated equipment) and EN 55103-1: 2009 A1: 2012 (a product family standard for audio, video and entertainment lighting equipment for professional use).

EN 55032 is now the only route to compliance. Not only must new products being sold in the European Union comply with EN 55032, old products sold on the market before March this year are also required to prove compliance, as there is no grandfathering allowed.

EN 55032 is an attempt to harmonise the testing on several different types of equipment, which in the past have differed greatly in their design, operation and internal technology, but which now all share very similar internal technology and functionality. The testing for a piece of IT equipment in the old EN 55022, compared to EN 55032 is therefore very similar.

New devices, new requirements

However, EN 55032 now recognises that other equipment, such as set-top boxes, TVs and professional audio and video equipment, have more in common with an IT device than they do with a custom-built separate device in its own right (as they may have done in the past when multimedia technology was not so advanced) and therefore the test approach to these devices should be the same, although the way that different multimedia equipment is exercised during testing differs considerably from product to product.

For IT equipment that was tested previously to the old EN 55022 standard there is very little difference. Aside from the power disturbance measurement, which is no longer permitted, limit values and measurement procedures remain largely unchanged.

For other equipment, which is now newly covered by EN 55032, radiated emissions are likely to be required to be measured in a much higher GHz range, rather than up to the 1GHz requirements of some of the old standards. This will depend on the highest internally generated frequency within the product. As a lot of devices now have a PC-based architecture, their processors tend to have high-frequency clock signals, which would necessitate testing radiated emissions to a higher frequency than when tested to the previous standards.

The requirements of EN 55032 also demand more focus on interface ports, port type and cable options including possible length of the cables and the type of signals on each port, with previously necessary multiple measurements for multifunctional devices no longer mandated. However, EN 55032 does require testing on at least one of each type of port per function. For example, if the equipment under test (EUT) has two BNC ports, one an input and the other an output, both ports are candidates for conducted emissions testing.

EN 55032 has also added clarity regarding the applicability of the I/O port conducted emissions test, which was missing in EN 55022. This limits the testing to ports that have cables that are greater than 3m long. However, audio ports such as microphone inputs and speaker outputs longer that 10m are also included in the scope of this standard and need to be tested for conducted emissions.

Streamline the testing process

A successful testing programme is the result of you disclosing as much information to your chosen EMC test laboratory about the EUT as early as possible in the project cycle, with a special focus on the display capabilities and I/O port mix.

Details about the port type and expected cable construction can have a dramatic effect on both the test method deployed, and the time the testing takes. It is therefore vital that you give your chosen EMC testing laboratory a full understanding of the EUT, its primary and any secondary functions, display type, typical display content, display resolution capability and environmental parameters.

Before commencing testing, the laboratory undertaking the EMC tests will also require details on the ports, including whether the port lines are balanced or unbalanced, the number of lines or pairs, and whether they are screened or unscreened. This will help the laboratory to develop a realistic test plan, enabling you to more accurately anticipate time-to-market for products.

For products that have been tested to the previous standards, a simple gap analysis can be carried out and recorded in a ‘consultants opinion letter’, which can be included in the equipment’s relevant technical file. This letter would state where previous testing carried out meets the requirements of EN 55032, as well as identify where further testing is required.

Currently the EU is the only market harmonised to EN 55032. In some cases, the test methods and set-up requirements between standards are not compatible and will require otherwise seemingly redundant testing, so if you are shipping products to multiple markets outside the EU, it is likely that you will need to evaluate your product to a wider variety of standards.

About the author
Richard Poate is senior manager at TÜV SÜD Product Service, a global product testing and certification organisation, and at its sister company, TÜV SÜD BABT, a leading radio and telecommunications certification body