York EMC 2003

1st July 2003, Vanbrugh College, York University

This years York EMC event was located in the Vanbrugh College rather than the usual location of the University Events centre.  The relocation was possibly due to the smaller than usual trade exhibition accompanying the conference (18 exhibitors, 5 of which are businesses of York Electromagnetic Services; YES).  The conference itself had enough papers to run two simultaneous sessions as in previous years, however, it was relatively obvious that YES also dominated the speaker list as well as the exhibition space, providing 5 papers of the 15 presented.

Figure 1: Vanbrugh College, venue 

for York EMC 2003

Conference

Despite the relatively late notice of this event it still had a good attendance with over 120 delegates that made the conference and exhibition look busy throughout the day.  One of the highlights of this conference was the accommodation of engineers relatively new to EMC; one of the morning sessions was dedicated to “EMC Basics”.  The “EMC Basics” session had a high attendance, attracting approximately 70% of the delegates, proving that a demand for this type of seminar/training does exist. 

Basic Programme

The basic programme consisted of a “What is EMC” session from Les McCormack and David Welsh of YES, covering the basics of emissions, immunity and ESD and sources of these in electronic systems and the environment.  The presentation also included a brief overview of the EMC directive (89/336/EEC), use of technical construction file (TCF) and a quick look at the RTTE directive (99/5/EC).  The second session in the morning started with Dave Imeson of Compliance Europe Ltd presenting the changes to the EMC directive (EMCD) that are to be implemented in 2003, including the increased coverage for apparatus made from combinations of already approved sub-systems, certain components and sub-assemblies, ready-made connecting devices and fixed installations. Nick Wainwright of YES concluded the morning session with a subject that many seasoned EMC professionals have some problems with; keeping up-to-date with EMC standards in a complex and seemingly ever-changing and expanding list of standards and directives.

The afternoon session was not quite a basic session.  The first presentation of the afternoon was from Dai Davies of Nabarro Nathanson (Solicitors) on Product Recall, the presentation mainly consisted of a series of examples and discussions around them.  Dai made the presentation interactive by asking the audience many questions, most of which went incorrectly answered that illustrated the difference between the legal and engineering view of a product recall more than any genuine ignorance of the subject.  The overall conclusion was that although not a legal requirement and not reducing a company’s liability, it did reduce the probability of being sued, but even the best recalls only recover 33% of products in the market.  This was followed by a dryer presentation on the impact of change to EN61800-3 (A11) on filters and machine tools by Ray Acosta of Schaffner.  The Schaffner range of filters was heavily featured, but this did not detract from the general conclusion that machine tools would need more filtering to meet the EMC regulations to cover control and communications and not just the motor systems as is currently the situation.

The final session of the basic programme included a presentation by Didier Bozec of YES on tests conducted on commercial off-the-shelf switching power supplies (SMPS) and switched electronic load controllers (SELC; a light dimmer) under different load conditions (25%, 50% and 100%).  The results were surprising, showing that under some test conditions the lighter loading created more conducted noise for SMPS and more harmonic content for the SELC.  As these items are all compliance tested with 100% loading applied there are implications in real applications of the results where worse than expected noise could be generated under light load conditions and when load levels switch.  The final presentation (by the author of this piece) examined a novel method of assessing the EMC impact of design changes, without having recourse to re-testing.  The methodology is based on design failure mode and effect analysis (DFMEA) and allows assessment of changes prior to their implementation to determine if they are commercially sensible and what the test cost implications will be.

Figure 2: Didier Bozec gives an 

animated presentation.

Technical Programme

The morning session included papers on the FOR-EMC Project, Radiated Emissions from Automotive Harnesses, Ambient Cancellation Techniques and Simulation of Shielding Effectiveness.  The FOR-EMC Project presented by Chris Marsham of YES looked at the influence that new member states of the EU will have on the EMC and other CE marking legislation.  The new EU members are keen to learn about EMC technology and obviously sell into the rest of the EU.  There was also a discussion on possible qualifications, such as the US NARTE examination, but no deliverable on this within the remit of the FOR-EMC project.  The Automotive Harness paper (the second paper by this author) examined the effect of different harness lengths on radiated emissions and discussed the problems of different standards specifying different lengths, not only for radiated emissions testing but also for other automotive tests.  The overall conclusion was that the harness length made little difference to overall signal amplitude level but had a major impact on resonance patterns, consequently harness length can directly affect the spectral emission from a Device Under Test (DUT).

The late morning sessions continued with a paper by David Mawdsley of Laplace on using cancellation techniques to eliminate a noisy ambient and recover the emissions from a device under test, even where the ambient was higher than the DUT emission.  The results illustrated good results for narrowband noise but poor for broadband due to very close DUT and ambient signal levels in the examples used.  In practice the poor broadband result was suggested as being unusual, but without any supporting data it will be difficult to see the method gaining a wider acceptance.  The final morning presentation by Paul Duxbury of Flomerics concluded with the simulation of shielding effectiveness using the FloEMC transmission line matrix (TLM) field solver.  The presentation considered effects such as measurement locations and non-continuous surfaces to illustrate errors in simpler calculation methods and presented high correlation between measured and simulated results for several enclosures with various aperture configurations.

The afternoon session of the technical programme commenced with a guide to good practice for GTEM cell use by Angela Nothofer of NPL.  The presentation provided good correlation between GTEM and OATS for radiated emission results and good field strength uniformity during immunity testing.  Ian Cutler, an independent consultant, presented the medical device directive; this looked at the relatively complex situation with respect to conformity assessment and the applicable technical standards.  The final two presentations were by University of York speakers; firstly Francesca Faraci presented experimental simulations of the interaction of telecommunications system with the human body, primarily mobile phones at 900MHz and some 1800MHz data was presented.  The subject of hot debate at the present, the results looked at the heating and resonance effects and used safe absorption rate (SAR) data to determine safe levels.  Unfortunately, as with a lot of this subject at the moment, there was little measured data available to back up some of the more complex simulations and hence the results are still very much open to interpretation.  The final presentation continued with the biological theme, Darren Stone presented a method using resonant perturbation methods for making total body water content observations.  

Proceedings

The proceedings contained the presentations from both Basic and Technical programmes.  Unfortunately not all presentations had been written up into a paper and consequently some of the information is available as “thumbnails” of the presentations only.  The presentation only content lacks some of the detail and any additional reference material you can find via a proper paper submission.  This makes the proceedings less useful after the event and also makes the presentations appear to have a more commercial bias than was evident at the conference itself; the proceeding copies of the presentations from Schaffner, Flomerics and Laplace do not do justice to the information provided verbally.  

Figure 3: The exhibition was busy

during conference breaks.

Overview

I am a little biased in having been to many exceptionally good EMC conferences at York in previous years.  It was clear at this conference that papers on EMC are getting harder to come by and maybe even EMC itself is not as hot a topic as in was in the mid-to-late 1990's.  The relatively late call-for-papers would not have helped and it did feel like YES had stepped in to fill the gaps in many places that would have otherwise been filled by papers from commercial sources (test houses and their customers for example).  The late call-for-papers could also explain why some of the presentations had not been written up into formal paper submissions.

I am a strong believer that a short 1-day conference, such as York EMC, can provide a much better value-for-money delivery of EMC information than the 4-day events offered in the US and the larger European conferences.  Unfortunately this year the York EMC conference was not well supported by the EMC industry for whatever reason and failed to live up to my high expectations.  The highlight was the Basic sessions for newcomers to EMC, but for “veterans” such as myself there was less to gain this year than in many previous York EMC conferences.  Hopefully next year the call-for-papers will be issued at an earlier date and the conference will receive better support from the EMC industry.

Martin O’Hara

4th July 2003

 


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