In message <[email protected]>, dated Fri, 22 Jun 2007, John McAuley <[email protected]> writes:
>What is not clear to me is exactly what constitutes a system under this >new definition ? Without doubt a solution comprising a single rack with >maybe 2 servers, a number of data storage units, a UPS and a power >distribution unit should be classed as a 'system', if marketed as so >described. This was sorted out during the lifetime of 89/336. Unfortunately, it's very difficult to get 'interpretations' (translations!) of the obscure wording of Directives and Guidelines officially confirmed. The keywords above are 'if marketed as so described'. If the manufacturer has a catalogue item composed of several of his products, especially if it's offered at an inclusive price, then it's reasonable to say that the manufacturer can test that 'system' as a whole. >But what about the other end of the scale - where you could have a >solution spread across 30 racks in a data-farm, with only half of them >populated initially and the customer adding to the installation >incrementally. Is this a 'system' ? No, because it's not 'made commercially available as a single functional unit, intended for the end user'. It's an ad hoc collection of compliant apparatus, which is a 'fixed installation' in the terminology of 89/336. >If so, how would you practically perform the EMC Assessment ? At some >stage does a large installation like this become a 'fixed >installation' ?? Which is important, as, 'fixed installations' are >treated very differently to 'systems' in the new Directive. Size isn't relevant; if it's an ad hoc collection, it's an 'installation'. The use of the word 'fixed' has caused a very great deal of problems, and it's far from clear why the new Directive uses several of the restrictive words that it does in this context. > >Finally, if a customer asks you to specify a solution for a particular >need they have - is the resulting offering treated as a 'system' ? i.e. >it was not marketed (made commercially available) by you as a single >functional unit but put together by you in response to a request. No, it's an ad hoc collection of compliant apparatus. I have advised manufacturers to reinforce the ad-hoc nature by itemising each piece of apparatus separately on the invoice, rather than showing just an inclusive price. The Guidelines to 89/336 unfortunately appear to confuse all this by discussing two different meanings of the word 'system'. Read carefully, 6.4.1 discusses a 'common understanding', which actually describes a 'fixed installation', and 6.4.2 , which discusses 'systems' within (i.e. as defined in) the EMC Directive. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
