We often get asked what is EMC testing, why is it testing performed, who should be performing EMC testing and how do we do the testing. So this brief article will attempt to answer these questions in a non technical manner. Hopefully after this you will understand why compliance testing is so important, why using a testing laboratory that can perform the testing correctly is critical and what you should consider when choosing an EMC testing laboratory.
What is EMC testing
EMC testing is the widely used abbreviation of electromagnetic compatibility testing. As you may have read in previous articles on our site, electromagnetic compatibility testing is to provide a level confidence that electrical and electronic products can work together in the same electromagnetic environment without causing interference to other products. There are two distinct categories within EMC testing.
This is the amount of electrical energy that emanates from the product. These emissions are measured in different ways using various defined methods and equipment. Usually it involves the measurement of conducted emissions i.e. via a cable or conductive path and also radiated emissions via the air i.e. non-conductive path.
This is the ability for the product to withstand externally electrical influences. These influences during the EMC testing are a set of simulated real life phenomena that may affect the product. All of these tests are designed to simulate real life occurrences. The test levels that are applied are to also specified to simulate the expected electromagnetic environment. Immunity EMC compliance is only usually mandated for military, automotive, medical and consumer products for Europe i.e. the CE mark.
How is EMC testing performed
EMC testing involves using very specific test equipment and EMC standards. The test equipment and test sites used must conform to the technical specifications of the standards. You should always ask the laboratory if all the equipment they use including the test site comply with the referenced technical specifications. The EMC standards specify the methods used to measure the quantities either directly or through other referenced standards. In order to know how to test the product, it first must be determined what standards apply to the product. Each country or region has specific product standards that an be verified through the appropriate regions journal or listings. These listings are usually freely available online and typically have specific dated versions of the standards that are accepted. The decision of which standard to apply should be based upon the product’s primary function and the intended electromagnetic environment that the product is intended to be used in. In some cases there maybe multiple standards that could be applied, typically only one requires to be applied. If no product specific standard is clear then the most suitable generic of general standards should be applied. Please also note that additional Wireless Radio equipment testing maybe required, see our blog articles including “EMC compliance when adding Bluetooth“.
Who should be doing EMC testing
EMC testing should be conducted in accordance with the standards arranged or performed by the responsible company or organization selling or distributing the product within the region. This choice of using and EMC testing laboratory if required should be based upon the labs abilities. Some of these abilities include; Technical ability, accreditation, test equipment, testing facilities, trace-ability and accuracy.
To have any confidence in the conducted EMC testing results it is essential that you understand the basics. The measurement can be affected by all the components within the measuring system and also the configuration of the product itself. It is essential that the product is configured and stimulated or exercised in accordance with the EMC standard that you are using to show compliance. It is equally important that the measuring equipment is suitable and calibrated or verified appropriately. A good example is one of the biggest cost to an EMC testing laboratory, which is the actual a test site itself. A radiated emissions test site for most commercial EMC testing standards has a specified characterization. This is based upon an ideal Open Air Test Site (OATS) site or Indoor Open Air Test Site (iOATS). Typically the site is calibrated and has a measuring distance of 3m (minimum) and a 1m to 4m antenna mast. The cost of such a site can be staggering, along with the running costs of calibration and cost of other required equipment. This is why lots of companies can perform EMC testing, but you have to consider what you are paying for i.e. is the testing actually done correctly? The declaration of compliance (DoC) is made by your company, is based on the evidence that you supply. Will the evidence ever be in question, if one of the major components of the measuring system i.e. the test site does not the specification.
Why do EMC testing
EMC compliance is mandated throughout many global markets. EMC Testing is not mandated but you must be able to demonstrate EMC compliance. The most straight forward method of showing compliance to the EMC standards is to perform testing in accordance with the required EMC standards. As stated previously it is strongly advised the EMC testing laboratory can perform the testing correctly. It is not possible for many persons and companies to easily assess the laboratories competency. However a good indication of competency is to verify if the laboratory has been assessed by technical experts through an accredited body. NATA is an Australian accreditation body, that is a part of “International Laboratory Accreditation Cooperation” (ILAC) which is accepted by many other countries.