Doug: It would seem logical that the shield will guarantee a high degree of immunity to local radiated fields. If the filter is a commerical one its specs are probably dependent on the shield being in situ. Even though it may meet the EMC test requirement, there is an added degree of safety i.e. equipment malfunction) with the filter in place. If there is line voltage appearing on any of the components and they are in areas used by service people then the question of electrical safety is addressed by having a shield. This is only my opinion.
Ralph Cameron EMC Consultant and Suppression of Consumer Electronics (After Sale) ----- Original Message ----- From: POWELL, DOUG <doug.pow...@aei.com> To: <emc-p...@majordomo.ieee.org>; Treg Listserv (E-mail) <t...@world.std.com> Sent: Wednesday, December 08, 1999 2:19 PM Subject: RE: Open Frame EMI Filters > > Hello once again, > > I have already received a number of replies to my query indicating that the > metallic enclosure is required for low inductance coupling to the components > or to prevent radiation between circuits within the product. This is not my > question. > > Please remember that one of the criteria that I described for the open frame > is the passing all applicable EMC tests. This means that the open-frame > design that I propose meets both radiated and conducted emissions levels, > without the metallic box. My questions deals more with why is the enclosure > required if product passes the tests without it. In the past I have > designed a few products with a simple PCB for emissions control. I > compensated for the internal re-radiation problem. > > Recently I heard of a commercial EMI Filter company that says the enclosure > is required and that the encapsulant is a requirement. I disagree. > > -doug > > ======================================= > Douglas E. Powell > Regulatory Compliance Engineer > Advanced Energy Industries, Inc. > 1625 Sharp Point Dr. > Fort Collins, Colorado 80525 USA > m/s: 2018 > --------------------------------------- > 970-407-6410 (phone) > 970-407-5410 (e-fax) > 800-446-9167 (toll-free) > mailto:doug.pow...@aei.com > http://www.advanced-energy.com > ======================================= > > > > > > > > > Hello group, > > > > > > For years I have used off-the-shelf and custom EMI filters > > with a fully > > > enclosed metal canister. Why is this enclosure required? Are there > > > specific provisions in the standards? My idea is to build > > up the filter > > > circuit on a printed circuit board and make it an integral > > part of the > > > power supply. > > > > > > I am currently looking at EN133200 which has certain seal > > tests but after > > > reviewing these, they all appear to be related to climatic or > > environmental > > > conditions. If the product passes these tests without the > > enclosure it > > > would seem that the product has passed, period. > > > > > > Alternatively I have considered removing the nomenclature > > "EMI filter" and > > > simply call it an input module, then evaluate it as a part > > of the overall > > > system. If it passes the EMC and Product Safety > > requirements, can I call > > > the job complete? > > > > > > Any thoughts? > > > > > > ======================================= > > > Douglas E. Powell > > > Regulatory Compliance Engineer > > > Advanced Energy Industries, Inc. > > > 1625 Sharp Point Dr. > > > Fort Collins, Colorado 80525 USA > > > m/s: 2018 > > > --------------------------------------- > > > 970-407-6410 (phone) > > > 970-407-5410 (e-fax) > > > 800-446-9167 (toll-free) > > > mailto:doug.pow...@aei.com <mailto:doug.pow...@aei.com> > > > http://www.advanced-energy.com <http://www.advanced-energy.com> > > > ======================================= > > > > > > --------- > > > This message is coming from the emc-pstc discussion list. > > > To cancel your subscription, send mail to majord...@ieee.org > > > with the single line: "unsubscribe emc-pstc" (without the > > > quotes). For help, send mail to ed.pr...@cubic.com, > > > jim_bac...@monarch.com, ri...@sdd.hp.com, or > > > roger.volgst...@compaq.com (the list administrators). > > > > > > > > > > > > > > > > --------- > > This message is coming from the emc-pstc discussion list. > > To cancel your subscription, send mail to majord...@ieee.org > > with the single line: "unsubscribe emc-pstc" (without the > > quotes). For help, send mail to ed.pr...@cubic.com, > > jim_bac...@monarch.com, ri...@sdd.hp.com, or > > roger.volgst...@compaq.com (the list administrators). > > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > jim_bac...@monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
