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EMC tests – what are they, and why are they necessary?

 

 

Your new product. An advanced device intended for the military, medical, transport, or simply consumer sector. Developed down to the smallest detail for several months or even years. Great commitment from your entire team – tens if not hundreds of hours of engineers’ and other specialists’ work. When everything is seemingly ready to introduce your new product to the European market, the critical issue of electromagnetic compatibility (EMC) testing arises. It turns out that to legally sell and use a device in the European Union, it must meet certain standards. Lack of EMC certification can, in some cases, even have financial or legal consequences. So what now?

The number of highly specialized and household electronic devices in our everyday environment is constantly growing. They all interact by emitting and receiving electromagnetic waves, depending on whether and how they are connected and/or how far apart they are. This means that they may adversely affect the functioning of other devices or may themselves be disturbed by the emission of EM waves by machines in their vicinity.

The legal formalities

The concept of electromagnetic compatibility describes the equipment’s ability to operate in a specific electromagnetic environment. The electronic device must be resistant to disturbances emitted by other machines and should not interfere with the devices running in the same environment. Electromagnetic compatibility tests allow for verifying the compliance of electronic products with the applicable requirements of the EMC Directive (EU Directive 2014/30/EU). Thanks to this, their proper functioning in a given electromagnetic environment is guaranteed, as well as the safety of use.

The directive mentioned above concerns manufacturers of electrical, electronic, and lighting equipment. It defines obligations that need to be followed before placing the product on the market. It is essential to comply with Directive 2014/30/EU and harmonize the standards. However, it is also crucial to have adequately prepared technical documentation and affix the CE marking on a product. This mark means compliance with the quality and safety standards provided for a given product in the relevant legal regulations of the European Union.

Electromagnetic environments

Electromagnetic compatibility is a complex and multithreaded issue. Expectations towards it should be considered in the very first stages of the project. Depending on the purpose of the device and its specifications, the EM field will have a different effect on the machine components and their functioning.

The electromagnetic environment can be generated artificially or naturally, whether intentionally or not. It is naturally produced by the Earth, lightning strikes, celestial bodies, and even humans. Artificial electromagnetic fields are closely related to the production, transmission, and direct use of electricity by given devices. Wireless communication and TV and radio broadcasts also generate EM fields, but they do so on purpose. All of the above means that the manufacturer of an electronic product should define, as soon as possible, how a given device will behave in a specific electromagnetic environment. Both the emissions of disturbances and operation under the influence of interferences from other sources should be taken into account.

Factors that may affect the operation of the equipment may be, e.g., voltage surges in the device cables, static electricity discharges, power outages, or fluctuations in the socket. Radio and TV transmitters, wi-fi routers, and other broadcasting equipment emit electromagnetic interference. Any electrical product may also be affected by gate pilots, mobile devices, medical and scientific instruments, intelligent transport systems including GPS modules, and even fluorescent lamps.

The power of cooperation

In our daily work at Unisystem, we face many challenges in terms of not only the assessment of electromagnetic compatibility but also the safety, quality, and usability of the final product. Bringing the device into compliance with the applicable standards begins at the first stages of its design. Our engineering staff works closely with project managers and the clients themselves – dialogue and joint work on the specification from the beginning of the project allow us to learn about its possible threats and reduce delays and costs. By considering the EMC tests early enough, we can avoid the need to redesign the final device, which would involve its reassembly and the necessity to repeat the tests.

One of the most interesting solutions tested for electromagnetic compatibility is the RVT101HVLNWC00-B display from Riverdi (1280x800p, 1000:1, 850 cd/m2, operating temperature (°C): -20 ~ 70) intended for industrial applications. It is perfect for HMI control panels for medical and military applications due to EMC compliance, high resolution, resistance to external factors, and increased brightness. The full EMI study report is available on the Riverdi website.

Experience and knowledge

Block diagram of the tested device

Solving problems encountered, e.g., while testing the immunity of the product to static electricity discharges (PN-EN 61000-4-2), requires appropriate knowledge and experience. The TFT display tested by our engineers was hanging up during testing – the graphic controller kept self-resetting for initially unknown reasons. As a result, the device continued to work without a graphical interface, and only restarting it restored normal operating mode. At first, we searched for software flaws, but we have managed to identify a measuring point where the discharge was causing the device to shut down – it was the edge near the FFC tape of the capacitive panel.

In subsequent trials, various solutions were proposed, including using a shielded variant of the FFC tape. This was effective but generated complications in the form of increased project costs. The search for alternatives was started, and the answer was to find the very source of the discharge, i.e., the air gap between the protective glass and the display housing. Finally, it was decided to provide insulation by sealing the cavity with acrylic tape. As a result, there was no need for further shielding – the device was made resistant to electric discharges in the air, and the project expenses were significantly reduced.

EMC as a part of the whole picture

Careful EMC testing is one of the factors that allows you to design products safely, quickly, efficiently, and without unplanned disruptions. Today, almost all electrical or electronic equipment should have a level of immunity to electromagnetic interference expected for its intended use. Without compliance with the Directive, devices may malfunction or even be permanently damaged – this may endanger not only the project itself but also the client’s reputation.

Our priorities are electromagnetic compatibility cost optimization and emphasis on functionality and design. By choosing dedicated solutions recommended by specialists, you can be sure that the product will receive the appropriate certification – repeating the EMC tests will not be necessary, which will speed up the introduction of the product to the market.

Unisystem is a team of specialists who approach each client individually. We strive to ensure that each project we are involved in is of the highest quality. Contact us if you need any support in implementing your project.

 Uni's Guide