Avoid expensive redesigns

Imagine the following situation: You're sitting on a plane and the passenger next to you excitedly shows you his new smartphone. He taps away on it, looks out of the window and suddenly says: "Wow, I can even control the plane's elevators with my smartphone...".

What is intended as a joke here has a very real core. It is well known that electromagnetic fields of varying strength are generated wherever electricity is involved. Electromagnetic compatibility, or EMC for short, is defined as the property of a device not to disturb other devices by unwanted electrical or electromagnetic effects, or to be disturbed itself. EMC must be distinguished from electromagnetic environmental compatibility (EMEC), which deals with the effects of non-ionizing electromagnetic radiation on the environment and humans, including the problem of so-called electrosmog. More and more people are blaming this for diffuse health complaints.

EMC as a "matter for the boss
At a customer event held by Emitec AG (see box), Peter Wüthrich, who is responsible for the company's business with EMC test technology, pointed out a number of "footholds" that can be avoided in the development of new electrical devices and components. His message: "EMC is a matter for the boss." Because electromagnetic compatibility is, on the one hand, the legal compliance of product standards, and on the other hand, the quality in which a manufacturer ultimately wants to sell his products. The EMC basic standards - declared by the symbol "Conformité Européenne C E" - cover the whole of Europe:

• EN 61000-6-1:2007: Immunity for residential, commercial and light-industrial environments
• EN 61000-6-2:2005/AC:2005: Immunity for industrial environments
• EN 61000-6-3:2007 +A1:2011: Noise emitted by residential, commercial and light-industrial environments
• EN 61000-6-4:2007 +A1:2011: Noise suppression for industrial environments

In addition, there are various other product and testing standards

As Peter Wüthrich pointed out, not every C E sticker on a product is a genuine conformity mark. CE (without a space between the letters) also stands for "China Export". And there, the European standards are not always taken very seriously.

Redesigns due to EMC interference
Whether made in China or not, unwanted radio waves can become a problem. Experience shows that every electronics development has to be revised three to five times on average. Almost half of these cases are due to EMC interference. And redesigns are notoriously expensive: finding the sources of interference after the fact involves a great deal of time and effort. Moreover, the installation of interference suppression components is often not possible without compromising the design. And once a product is launched on the market that exhibits EMC malfunctions, the loss of image for the manufacturer is almost pre-programmed - not to mention the costs of a recall campaign.

According to Peter Wüthrich, these are reasons why EMC is a matter for the boss. Or to put it another way: EMC is a competitive advantage, protects European products from cheap imports and ultimately also reduces costs. After all, less support is needed for devices that function faultlessly. However: EMC tests are not free. Relying on your own engineers and simply affixing a "CE" sticker to the product is not enough, as Peter Wüthrich explains. Alternatively, of course, all the tests could be carried out by a laboratory specializing in this area. The advantage of this is that all tests can be carried out there in accordance with current standards and with the appropriate infrastructure, for example in a shielded hall. However, longer waiting times may have to be accepted, which means that only one test specimen is tested due to time constraints. And random samples from production to verify results are also not available.

External or internal tests?
Of course, it is better to carry out all tests internally. You are then ready at any time, can also "tinker" with EMC and continuously optimise the products. As a result, you are on the market faster, and the knowledge gained from the test series flows straight into new developments. The disadvantages of internal tests are that the necessary infrastructure must first be created and the necessary know-how developed. This is associated with larger investments - depending on the test facility selected.

The compromise recommended by Peter Wüthrich is a combination of internal and external EMC tests. But first it is important to determine which tests are critical to the system and therefore the most important. If possible, it should be possible to perform these tests internally. In this way, one retains the highest possible flexibility, especially when tuning and optimizing the products. Peter Wüthrich explained this using the following process: "At the beginning of every new development is the achievement of functionality. In the prototype phase, the next step is to dispense with everything that is not necessary for the functionality of the product. Afterwards it is necessary to achieve the legal EMC requirements by EMC tuning. This is done, for example, by empirically determining optimal filters and shielding. Or support capacitors are soldered on and tested to see whether they bring an improvement. In short, all prototypes are first tested in-house and then the final design is tested externally. Special tests and plausibility checks are also carried out in cooperation with an external test laboratory. However, even this "compromise solution" is not entirely trivial, because the necessary knowledge and appropriate test equipment are also required for the tests carried out internally.

Less expensive thanks to tests during development
The advantages of EMC during development are obvious: You can develop faster and you automatically acquire EMC know-how. Testing immediately after each development step also increases flexibility and avoids waiting times for an appointment with an external test laboratory. There is also no need for logistics for large test items. Proper EMC tuning shifts the focus from "as good as possible" to "as good as necessary" and leads to more cost-effective products overall. Indes: As great as aircraft control via smartphone could be: It's better to see it in simulations than in reality. Because only very few passengers are likely to really enjoy it - or at best the competitors and the lawyers.