EMC design, test and management services
Meeting and testing to the European Directives
EMC R & D projects
What is EMC?
The term Electromagnetic Compatibility (EMC) covers all aspects of the interaction of electrical and electronic equipment with its electromagnetic environment and with other equipment.
Any electronic equipment can be affected by external disturbances: radio frequency fields, electrostatic discharge, conducted transient interference or supply voltage variations. Or it could generate its own interference emissions. Digital and microprocessor-based systems in particular, as well as electromechanical devices such as brushed electric motors, create noise which affects radio reception across the spectrum.
Good EMC design minimises both susceptibility to, and generation of, electromagnetic disturbances.
Why is it important?
Because of the threat to legitimate users of the radio spectrum, many countries limit the interference that equipment can generate. Some of your customers may specify that their system performance must be maintained in the presence of electromagnetic interference. Even if they don't, you may have discovered an EMC problem with your equipment in a particular installation.
All products marketed within the European Economic Area must comply with the provisions of the EMC Directive or its relatives the R&TTE or Automotive EMC Directives, which require both adequate immunity from interference and the minimum generation of interference. The US have had emissions legislation for many years, Australia has implemented its EMC Framework, and other Far Eastern countries have taken up the same process. If you sell within any of these countries, or into other safety-critical industries such as transport or process control, your product's EMC performance is important.
But it's such a difficult subject...
There are many unknowns surrounding the question of EMC. What are the applicable standards and how do I find out about them? Which tests should I do and how do I do them? If the equipment doesn't pass the tests, what can I do about it? And most importantly, will my product be reliable and benign in its intended electromagnetic environment? You need answers to all these questions. That's where EMC consultants Elmac Services can help you.
EMC design, test and management services
Electromagnetic compatibility requirements in general have seriously affected many companies making electrical and electronic equipment. A major problem, which afflicts both large and small firms, is that EMC is a foreign subject: because it involves a combination of electrical, electronic, mechanical and software disciplines, it easily falls down the cracks between them.
RF electromagnetic phenomena depend on physical layout and stray, unintentional features like proximity of conductors and gaps in housings. Because product complexity means that unexpected interactions can and do occur, EMC has earned itself the name of a "black art". This is not actually so - all the processes involved have a solid physical foundation. But to get to grips with them calls for extra time and effort.
In these circumstances, the engineering approach is to call in someone with expertise in the field, to guide the resident designers towards the right solution. This needs someone who has specialised in EMC but has a background in design. That's where Elmac Services - the UK's premier EMC consultancy - comes in.
The range of possible requirements is very wide. Here are a few of the projects we've taken on:
A large company wanted to establish its own EMC test facility for compliance testing of its product range. Elmac Services suggested the buying list for equipment, costed and evaluated the alternatives, supervised setting up the facility, wrote the test procedures and trained a select handful of staff in doing the tests - who then passed on their knowledge to their colleagues.
Design reviews and remedial advice are a regular feature of our work. The best time to ensure EMC requirements are dealt with is in the initial stages of design. It's always necessary to make adjustments throughout the design process, and having someone with EMC design expertise on hand to discuss the options and choices will ease the job of the in-house design team.
And if the worst comes to the worst, and you face court action (or need to take it) over an interference problem, we can act as an expert witness on your behalf.
Meeting and testing to the European Directives
The EMC Directive 89/336/EEC is very simple (although it's now been re-published in a new form, 2004/108/EC: see our short briefing). It, or its siblings the R&TTE Directive or Automotive EMC Directive, applies to all electrical and electronic apparatus likely to cause or suffer interference, and requires that such apparatus shall be so constructed that
- the electromagnetic disturbance it generates does not exceed a level allowing radio and telecommunications equipment and other apparatus to operate as intended;
- the apparatus has an adequate level of intrinsic immunity of electromagnetic disturbance to enable it to operate as intended.
Elmac Services has been involved with the EMC Directive since it first became public at the beginning of the '90s. We've followed every twist and turn of the legislation, the standards and the guidance. We know what's required and what isn't, and we have a good idea of the most appropriate approach for any individual case, whether you're a small company with a single bright idea or a large organization with millions to spend. System builders, panel builders, box builders, special applications and environments, components - we've looked at all of these. We have strong links with several competent bodies and can act as your TCF advisor where necessary. If a TCF is right for you, we'll recommend it - if not, we won't.
Typically, we can sort out most issues in a single day's visit, to see what your products are, how you sell them, and how your company operates. From this we can make recommendations as to the best route for EMC compliance for any given product range, what tests might be needed (if at all), and what standards you should use (if any). The result - we are told by many clients at the end of the visit - is a much greater understanding of the company's exposure to the legislation and what is the most cost-effective way to meet it.
Increasingly, companies are investing in their own test facilities to apply the standard EMC tests to their products. The choice of equipment is wide and is complicated by the fact that different products can have widely differing test requirements. Elmac Services can advise you on the most cost effective test system to specify; and we can also offer you in-house training in their use to make sure you have confidence in your test results.
If you feel that a visit could benefit you, just let us know and we'll arrange it.
EMC R & D projects
We are also able to take on a variety of larger projects with an EMC theme, either alone or in partnership with other relevant organisations. Some examples of recent work include:
If you have a project that is EMC related, we'll be happy to discuss it with you.
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