IEC 950 does not include OC III mostly because little IT equipment fits that application. There are many things which could be added to the standard, but have been left out for the sake of a "slim" standard. Even so, we may be swelling well beyond current limits with other special conditions like outdoor operation, walk in sized equipment, telephone central office equipment. If you and enough others find higher overvoltage categories a need, proposals to modify 950 might be appropriate.
1) How does one "certify" or "list" a product to 950 standards in an OC III environment? Design to 950 using the spacings for OC III from IEC 664. You will have more generous spacings so there will be no conflict with 950. 2) Does agency turn a blind eye? They are unlikely to insist on OC III if you ask for IEC 950 approvals, however, they are probably quite willing to certify you have spacings compliant with IEC 664 OC III in addition to IEC 950. 3) Is there an ethics or legal problem here? Ethically you should design to meet the needs of the expected product environment. If you fail to do so you are likely to get away with it, but should a court case arise, the jury is free to decide if you did the ethically correct thing. Foreseeable misuse is a powerful argument. You are liable when the court decides so. You can depend on your lawyers or on your design. Bob Johnson (on TC74 WG8 and UL 1950 IAC, but not speaking for either of them) "POWELL, DOUG" wrote: > Hello PS group, > > I would like to hear the opinions/recommendations of the EMC-PSTC group and > especially anyone who has ever worked on a committee for the development and > revision of IEC 950, EN60950, UL1950, CSA C22.2 No. 950 and any other > national equivalents derived from IEC 950. > > Over the years my company has designed and built industrial power supplies, > primarily for vacuum deposition, etching, and ion implantation in the > semiconductor manufacturing equipment industry as well as power delivery > systems for glass coaters, tool hardening, inductive heating, etc. All > these are generally Overvoltage Category III (OC III) installations. > > Most companies in my business use the 950 family of standards for the safety > certification of their products. I believe that at one time in history this > was valid due to the lack of industrial standards for products of this type. > I also believe that the 950 standards are probably the best as far as > engineering input goes. However none of these standards include equipment > for OC III. Since the 950 standards are developed from IEC 664-1, it seems > to me that an OC III should be possible under IEC 950. > > I hope my questions are simple: > > 1) How does one "certify" or "list" a product to 950 standards in an OC III > environment? > 2) Does agency turn a blind eye? > 3) Is there an ethics or legal problem here? > > ================================== > Doug Powell, Compliance Engineer > Advanced Energy Industries, Inc. > Fort Collins, Colorado USA 80525 > > doug.pow...@aei.com > 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, > j...@gwmail.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, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
