Michael, In looking at the standard to answer your question, you should refer to Section 8.1 of the most current EN55022 (EN55022:1998/CISPR 22:1997), which was published in the OJ earlier this year and was mandatory as of January of this year.
Specifically, the 10th paragraph of section 8.1 states...."In the case of printed wiring board assemblies (PWBA), separately marketed for the enhancement of divers host units, the PWBA (such as ISDN, interface, CPU, adaptor cards, etc.) shall be tested in at least one appropriate representative host unit of the PWBA manufacturer's choice so as to ensure compliance of the PWBA with the entire population of hosts in which it is intended to be installed. The host shall be a typical compliant production sample. PWBA intended to be class B shall not be tested in host which are class A." If one interprets the phrase "such as ISDN, interface, CPU, adaptor cards, etc." to mean "such as ISDN cards, interface cards, CPU cards, adaptor cards etc." then neither of your options would be valid. If one interprets the reference to CPU to mean motherboard, then it seems that your option a is valid. You may find further guidance in the following document: GUIDELINES ON THE APPLICATION OF COUNCIL DIRECTIVE 89/336/EEC OF 3 MAY 1989 ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO ELECTROMAGNETIC COMPATIBILITY (DIRECTIVE 89/336/EEC AMENDED BY DIRECTIVES 91/263/EEC, 92/31/EEC, 93/68/EEC, 93/97/EEC) This document states that any component, which performs a direct function is considered to be an apparatus as defined by the EMC Directive and thus subject to the Directive. The most pertinent section of this document follows: 6.2.3. Components performing a direct function These are components that can be placed on the market in retail outlets for distribution and/or putting into service, fulfilling the criteria defined in 6.2.1, therefore delivering a direct function. Plug-in cards, such as smart cards or input/output modules, designed for incorporation into computers are apparatus commonly found in retail outlets, and available to the general public. Once cards of this type are inserted in a PC they perform a direct function for the user. They must therefore be considered as apparatus and are, consequently, subject to the provisions of the EMC Directive. This does not mean that they must necessarily be intrinsically compliant from the EMC point of view in all cases, if this is either impossible or impracticable . However, in such cases, they must be designed in such a way that they become fully EMC compliant (emissions and immunity) when they are installed as intended in the apparatus, in any of its possible variants and configurations, without exceptions, and used in the electromagnetic environment determined by the manufacturer. The instructions accompanying the component must clearly indicate these requirements, the pertinent limitations of use and how to comply without resorting to an EMC specialist (such components are available to non-EMC specialists, for a wide range of applications). The manufacturer has the ultimate responsibility for this decision. Similar examples of components with a direct function are: * plug-in cards for computer systems, micro-processor cards, central processing unit cards/mother boards, electronic mail cards, telecommunication cards, etc.; * programmable logic controllers; * lift controls; * electric motors (except for induction motors, see chapter 5.4); * computer disk drives; * power supply units (PSU), where they take the form of autonomous equipment; * electronic temperature controls; Perhaps the above might shorten your research time or just further confuse you. Hopefully it's the former. The full text of the above quoted guidelines are available on the internet. I've lost the link from which I got it, but perhaps someone on the list can lead you there. If you have no luck finding it, please email me directly and I'll forward you a pdf file via email attachment. Best Regards Michael J. Azar / Senior Program Manager EMC Compliance Management Group http://www.emc-turntech.com Tel: 650-988-0900 x 103 Fax: 650-988-6647 ---------------------------------------------------------------- High quality EMC/Safety Consultancy and Approvals -----Original Message----- From: [email protected] <[email protected]> To: [email protected] <[email protected]> List-Post: [email protected] Date: Tuesday, August 24, 1999 3:20 PM Subject: CE Marking requirements > >Well group, if you care to help out another American confused by the specific >requirements for Europe, I would appreciate it. I seem to be getting varying >stories from different test houses as to what is required for one of our >products. These are big enough players that pitting one against another is not >something I want to undertake at this point. > >We currently manufacture a motherboard which is sold both by itself and with a >chassis which includes power supply, hard drive and floppy. We are currently >going through our internal EMC validation to ensure that we meet both FCC Class >B and EN 55022 Class B levels. Our experience on previous products has been if >we clear emissions, we haven't had problems in other areas, but we'll be testing >to EN 55024 of immunity, as well. > >The issue arises when we discuss testing of the system versus testing of the >motherboard alone. Within the US, the FCC regulations permit an additional 6dB >margin for "open chassis" measurement, so long as those frequencies fall back >within the class B levels with the cover on. This does not appear to be a >problem for our product. > >We have been told by different parties that for Europe, > >(a) there is no requirement to test "open chassis" and that we can CE mark the >board as compliant as long as we have shown that it can meet the class B levels >within a chassis of our choosing > >and > >(b) we are still required to perform "open chassis" tests, however, there is no >6dB margin and the board will have to meet the EN 50022 class B levels with the >cover off. > >We're having a little more difficulty making things work using the (b) approach. >I am specifically concerned about staying far enough below the levels that we're >not going to potentially pass today and fail 6 months from now due to a slight >drift in tolerances of components, test equipment or test engineers' >dispositions. > >I have the texts of the EMC directive, as well as the test requirements >specified in the above documents and I'm happy to wade through them if you can >point me in the right direction. I will be heading that direction in the next >day or two if I don't receive a response. I'm hoping, however, that someone in >the group can shave a few hours of exceptionally captivating reading from my >life by pointing me in the right direction. > >Regards, > >Michael Garretson >Compliance Engineer >RadiSys Corporation > > > >--------- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to [email protected] >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to [email protected], >[email protected], [email protected], or >[email protected] (the list administrators). > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
