Wading through that Electromagnetic smog
03 September 2018
Electromagnetic Interference is a form of pollution that can affect electronic equipment that is not protected from it.
Think of it as Electromagnetic smog. EMI can cause effects ranging from annoying noises on your car radio to serious accidents when safety critical equipment is caused to malfunction.
The EMC (electromagnetic compatibility) directive came into force in 1992 with a transitional period ending in December 1995. The directive is designed to ensure that the ability of a device, equipment or system functions satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment. The directive has had a few changes over the years but in principle remains the same. The latest iteration is EMC directive 2014/30/EU which came into force in April 2016. Compliance with the directive is usually by testing to standards or the manufacturer can provide a technical file to demonstrate compliance. Products need to be CE marked before they can go to market in the EU.
EMC shielding of an electronic enclosure is a mechanical fix for an electrical problem, the objective is to make the enclosure a Faraday cage or lots of smaller faraday cages within the enclosure. This is done with the use of electrically conductive gaskets to seal the seams and gaps and components such as EMI shielded windows for shielding display devices, honeycomb ventilation panels, shielded cable glands and metal cans for shielding components on the PCB. Filtering and absorption may also be necessary and of course good design.
Read the full article in the September issue of DPA
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