Let me first say that I think people are missing the thrust of William's initial question. The ensuing debate has taken a life of its own. (I can't resist a debate, so I'll weigh in after looking at William's question). William is wondering why EN 55024 (an ITE standard) only has immunity limits for residential, commercial and light industrial environments while EN 55011 (an ISM standard) has emissions limits for Class A (non-residential) and Class B (residential). Even if you throw out the difference between ITE and ISM, his question is still valid. The ITE emissions standard (EN 55022) has Class A and Class B limits just like EN 55011 (ISM).
I beleive its because the scope of EN 55024 is geared toward the residential, commercial and light industrial environment. If I were producing a piece of ITE equipment intended for a truly industrial environment, I would consider Class A emissions (yes Class A) from EN 55022 (assuming it's ITE). I would then look for the best fit of an immunity standard for industrial environments. Either a generic immunity standard such as EN 50082-2 or another whose scope is directed at an industrial environment. When applying any standard, we have to consider both the equipment classification and environment. As it stands right now, most ITE falls under EN 55024, but industrial ITE would need to look at a different standard geared toward an industrial environment. So, to answer William's question. I don't think we know why EN 55022 has Class A and Class B limits while its counterpart immunity standard (EN 55024) only has residential, commercial and light industrial limits. Only CENELEC can answer that. As engineers, we live with the standards as written, (while suggesting how they could be changed and questioning them when they're screwy). So, that's my answer to William's question (remember, as always, it's just the opinion of one man). As for the Class A vs. Class B debate ... I'm with Ghery on this one. Servers and mainframe computers are a prime example of ITE equipment whose "normal" usage environment is Class A (non-domestic). I also agree with Gert that Class A ITE can and will be used in domestic environments. However, I don't agree that this means that all ITE must meet Class B. There probably are a few people (not me) who would have a server or mainframe computer in their house. Why? I don't know. Maybe they have a home business. As the standards are now written, this doesn't make it illegal to market the Class A equipment as such. The standards simply require that the manufacturer put the "Class A warning statement" (See EN 55022) in the manual. By making the "Class A warning statement" a requirement, CISPR is acknowledging that Class A equipment could be used in a domestic environment. The responsibility is then put on the owner for taking measures to insure that the Class A equipment doesn't interfere with his or his neighbor's TV or radio reception. Consider the analogy of an industrial drill press. It is only required to meet industrial (Class A) emissions limits. However, there is a distinct possiblity that someone could buy one and put it in their house. Does this mean that all industrial drill presses need to meet Class B? Yes, the distinction between Class A and Class B environments is artificial. The entire standards themselves are artificial (they are man-made aren't they), but at least they are on paper and defined. The idea of "Essential Requirements" is even more artificial when compared to a standard. Essential Requirements can vary from one person to another and from one circumstance to another. Essential Requirements are only meant to fill in the gaps where standards may not apply or be adequate. There is no gap here. As the standards are now written, they define and allow for Class A ITE. As they are now written, any ITE manufacturer that has done their homework and can prove that their typical usage environment meets the definition of Class A can market in the European Union with Class A emissions. If CENELEC disapproves of this, then they would have needed to change CISPR 22 when it was harmonized as EN 55022. Long story short...It wasn't, so they don't. Of course this doesn't mean that a manufacturer shouldn't exercise due diligence. A piece of Class A or Class B equipment may have some spurious emissions that: have a high peak value but almost no quasi-peak; or fall into a frequency range not covered by the emissions standards. These are cases where due diligence and essential requirements would apply because there is no standard to cover such emissions, while, if the emissions are sufficiently high, there is a good probability that they could cause interference or upset of nearby equipment. I think that these instances are independent of the Class A vs. Class B argument. They could arise with either class of equipment. See ya's later. Chris Maxwell, Design Engineer GN Nettest Optical Division 6 Rhoads Drive, Building 4 Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: [email protected] > -----Original Message----- > From: Pettit, Ghery [SMTP:[email protected]] > Sent: Wednesday, December 06, 2000 11:25 AM > To: 'CE-test - Ing. Gert Gremmen - ce-marking and more...'; Pettit, > Ghery; 'William D'Orazio'; EMC Posting (E-mail) > Subject: RE: EN55024 > > > Gert, > > All ITE equipment must meet the Class B limits? Where does it say that in > either EN 55022:1998 or CISPR 22, 3rd Edition? Section 4.1 of CISPR 22 is > quite clear about what equipment must meet the Class B limits. There are > many types of ITE that do not fall into the examples provided in the > document. EN 55022 does not amend this part of the document in its common > modifications. As 89/336/EEC does not provide limits of any kind, where > am > I supposed to see a requirement that servers and mainframe computers > (which > are, indeed, ITE) must meet the Class B limits? > > Ghery Pettit > > -----Original Message----- > From: CE-test - Ing. Gert Gremmen - ce-marking and more... > [mailto:[email protected]] > Sent: Wednesday, December 06, 2000 1:14 AM > To: Pettit, Ghery; 'William D'Orazio'; EMC Posting (E-mail) > Subject: RE: EN55024 > > > Hi Group, > > The type of clause (see below) from EN 55022 about adding notes and > restrictions > to equipment is just the type the European Commission > objects against their use in the EN 55022 standard. > > The reason is that the CENELEC was asked to propose limits and > test methods, not to replace politics by limitng the applicability > of their standards. > > The use of such a clause to sell ITE equipment to Class A limits is > illegal > and will not hold when the presumption of conformity to the essential > requirements > of the EMC-directive is being tested. > > Information equipment is and wil be used in all environments, therefore > the distinction between such environments is artificial. > > > > Regards, > > Gert Gremmen, (Ing) > > ce-test, qualified testing > > =============================================== > Web presence http://www.cetest.nl > CE-shop http://www.cetest.nl/ce_shop.htm > /-/ Compliance testing is our core business /-/ > =============================================== > > > >>-----Original Message----- > >>From: [email protected] [mailto:[email protected]]On Behalf > >>Of Pettit, Ghery > >>Sent: Tuesday, December 05, 2000 11:46 PM > >>To: 'William D'Orazio'; Pettit, Ghery; EMC Posting (E-mail) > >>Subject: RE: EN55024 > >> > >> > >> > >>OK. EN 55022 is the ITE specific emissions standard. It does > >>have two sets > >>of limits with a statement that Class B is intended for certain product > >>types which may be used in a domestic type environment and a > >>statement that > >>Class A products should have a warning that they may cause interference > if > >>used in a domestic environment. CISPR 22 does not use the term > >>"industrial" > >>to define an environment. It merely warns that the class A limits may > not > >>provide enough protection to neighboring users of the RF spectrum if the > >>device is used in a domestic environment. > >> > >>Ghery > >> > >>-----Original Message----- > >>From: William D'Orazio [mailto:[email protected]] > >>Sent: Tuesday, December 05, 2000 2:37 PM > >>To: 'Pettit, Ghery'; William D'Orazio; EMC Posting (E-mail) > >>Subject: RE: EN55024 > >> > >> > >>BYI, EN55011 should read EN55022. > >> > >>William D'Orazio > >>CAE Electronics Ltd. > >>Electrical System Designer > >> > >>Phone: (514) 341-2000 (X4555) > >>Fax: (514)340-5552 > >>Email: [email protected] > >> > >> > >>-----Original Message----- > >>From: Pettit, Ghery [mailto:[email protected]] > >>Sent: Tuesday, December 05, 2000 5:33 PM > >>To: 'William D'Orazio'; EMC Posting (E-mail) > >>Subject: RE: EN55024 > >> > >> > >>EN 55024 is the ITE specific immunity standard. It is based on CISPR 24 > >>which makes no distinction between environments. EN 55011 is > >>based on CISPR > >>11 and relates to different product families. They do not come from the > >>same subcommittees in CISPR, so it's like comparing apples and oranges. > >> > >>Ghery Pettit > >>Intel > >> > >>-----Original Message----- > >>From: William D'Orazio [mailto:[email protected]] > >>Sent: Tuesday, December 05, 2000 1:22 PM > >>To: EMC Posting (E-mail) > >>Subject: EN55024 > >> > >> > >> > >>Gents, > >> > >> Why is it that EN55011 defines test levels for both industrial and > >>residential environments (class A, B) and EN55024 does not? Are > >>the levels > >>in EN55024 applicable to all environments (obviously not) so how does > one > >>define the test levels for an ITE in an industrial environment? > >> > >>Thanks in advance, > >> > >> <<...>> > >> > >>William D'Orazio > >>CAE Electronics Ltd. > >>Electrical System Designer > >> > >>Phone: (514) 341-2000 (X4555) > >>Fax: (514)340-5552 > >>Email: [email protected] > >> > >> > >>------------------------------------------- > >>This message is from the IEEE EMC Society Product Safety > >>Technical Committee emc-pstc discussion list. > >> > >>To cancel your subscription, send mail to: > >> [email protected] > >>with the single line: > >> unsubscribe emc-pstc > >> > >>For help, send mail to the list administrators: > >> Jim Bacher: [email protected] > >> Michael Garretson: [email protected] > >> > >>For policy questions, send mail to: > >> Richard Nute: [email protected] > >> > >> > >> > >> > >>------------------------------------------- > >>This message is from the IEEE EMC Society Product Safety > >>Technical Committee emc-pstc discussion list. > >> > >>To cancel your subscription, send mail to: > >> [email protected] > >>with the single line: > >> unsubscribe emc-pstc > >> > >>For help, send mail to the list administrators: > >> Jim Bacher: [email protected] > >> Michael Garretson: [email protected] > >> > >>For policy questions, send mail to: > >> Richard Nute: [email protected] > >> > >> > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: [email protected] > Michael Garretson: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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