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Latest News in Testing, Inspection and Certification

NTS News Center - Latest News in Testing, Inspection and Certification

Is there a preferred sequence for EMI, EMC Tests?

EMI Testing NTS BoxboroughOne of the questions we get asked often is about order of EMI/EMC testing.  Neither MIL-STD-461 nor RTCA/DO-160 specify the order of test performance.  Leaving aside the issue of Safety of Flight tests for aircraft (which typically must be performed prior to any other testing), there are a few different approaches to take in this regard.

The first approach is to perform an analysis of the equipment under test (EUT) before going to the lab to determine what tests are most likely to cause problems, and to start with them.

This approach works best if a customer does not have any idea how their product will stand up to the EMI/EMC compliance requirements. A design analysis tends to vet out significant concerns up front, potential design solutions can be discussed prior to qualification testing. At this point, the Subject Matter Expert (SME) should be able to prioritize the threats, and work with the customer to develop a suitable test order. This approach also provides an opportunity for pre-qualification evaluations to ensure the product will not have any issues during the qualification program.

The second approach is to begin with the most benign tests, usually the emissions.  These tests have virtually no chance of harming the EUT, but they sometimes prove to be the most problematic.  Emissions testing tends to reveal inerrant design flaws the most, and generally requires some level of redesign. Changes in design could necessitate repeating other tests if emissions is not completed first. However, there may be cases were a customer feels their product does not have any emissions concerns but is likely to be susceptible to a particular immunity test. They may choose to get the immunity evaluation out of the way first, and allow time for potential modifications prior to commencing with the remaining tests. This approach would also avoid costly retests or delays due to changes to the EUT.

The third approach is to begin with the most potentially damaging tests first. The philosophy here is that all is well and good if the EUT endures those tests with no issues.  However, if there are susceptibilities that require repair/redesign, those problems can be resolved before continuing with the other tests.

In summary, the EMC / EMI testing sequence used should be an iterative decision between the lab and the customer to determine which approach best suits the product and customer’s needs.

New EN 55022:2006 Requirements slated to go into effect

Manufacturers of Information Technology Equipment (ITE) intended for sale in the European Union should take note of some important changes that are slated to go into effect with regard to their EMC testing requirements under emissions standard EN 55022:2006.

In November 2008 the European Union’s Official Journal (OJ) published lists of standards for the Electromagnetic Compatibility (EMC) Directive and Radio and Telecommunications Terminal Equipment Directive (R&TTED). Both lists include references to EN 55022:2006 and its amendment A1, released in 2007.

EN 55022:2006 will supersede EN 55022;1998 and become the requirement for Information Technology Equipment (ITE) sold into the European Union after October 1st 20091 , with the requirements of Amendment A1:2007 coming into force one year later on October 1st 2010. What are the differences between the 1998 and 2006 versions of the standard and what new requirements will be introduced by A1:2007? Let’s begin by reviewing the history of CISPR 22 from 1997 onwards. International Standard CISPR 22 is the basis for not only EN 55022 but also for many of the other national versions of standards for ITE.

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Elliott Laboratories is currently equipped to conduct the EU free space testing above 1 GHz per EN55022:2006+ A1 and/or CISPR 22:2005 + A1 in all chambers at our Fremont facility. For more information about how this change affects your products or for a price quote to test your product, please contact us at info@elliottlabs.com or call at 408-245-7800.