Hi Folks Kyle make a very valid and serious point in his last paragraph => re-engineering of vendors' products. "CE Marking" of a vendor's product is a "minimum requirement" - suitability for the intended application in YOUR system is at least as important. This means preparing an adquate purchasing specification - and demanding proof that it has been met. If you make this type of purchase regularly then it is probably worth putting together a generic set of requirements which cover your customers requirements. You might also need a set of internal design guidelines for incorporating the purchased items into your own systems. We get these problems all the time as we design AC mains-powered communications/ITE fits for road/off-road vehicles (often using on-board 230V diesel generators). What is suitable for "office" use is rarely suitable for these fits without a lot of additional work (shock mounting, extra grounding, additional temperature/humidity control to name but a few areas). In particular, IEC/EN/UL 60950 equipment may well not be suitable for "rough" environments as there is generally absolutely no environmental testing involved in most evaluations. A couple of years ago we vibrated an "industrial PC" (admitted for a long time!) and most of the large capacitors in the PSU fell off the PCB's . Also, a large amount of aluminium (I am English - that's how we spell it!) dust was caused by a capactor rubbing on a heatsink, and this finished up all over the primary AC tracks on the PCB's. It still worked but it was very dangerous! It is thus very important to specify exactly what you want of the products you buy - and to make any installations/usage limitations clear in the documents you supply to your customers. Conditions of Acceptability again (and again!). Regards John Allen Thales Defence Communications Bracknell, UK.
-----Original Message----- From: Ehler, Kyle [mailto:keh...@lsil.com] Sent: 02 August 2001 20:57 To: 'Rich Nute'; 'EMC and Safety list' Subject: RE: Mains fusing Thank You so much Rich, Patricia, Mike, Jim, Ed, et al; Please do continue to contribute your wisdom to this forum. I spoke with my LES engineer and good friend at UL. [a good friend at UL is a handy thing!] Someday I should expound on the usefulness of proper care and feeding of your agency engineer.. In our discussions, I pointed out the grey area in 1950 2.6.2 & 2.7.4 [B] related to the conditions of applicability (PAG), and that this modular product is deployed in a rack mount environment where the mains cord is terminated in a polarized coupler (and disconnect device) making it nearly impossible to reverse the mains. In addition, the rack mount cabinet provides mains distribution to this module through double side breakers. I built my case on these two items and believe I can get an approval upon review. I'm told the remaining problem with this UPS is it fails 61000-4-5 in our lab, although it passes 801-5, and that it also fails conducted emissions when using QP->Avg techniques. I could be in for engineering a fire enclosure to contain wiring, coupler, filter, suppressor, and while in the area, a double side breaker -and of course, the attendant investigative redo. Normally, this would be good reason for vendor rejection, or at least a public drubbing in this forum, but we are committed for the short term to use this vendor's product and I cannot afford to risk any relationships -for now. The decision was never mine to make. And now we are in a familiar loop where the lab is used to re-engineer a vendor's product that is CE marked. Doh!! Statue today, pigeon yesterday... Thanks again, kyle my words, my opinions/mania...etc. -----Original Message----- From: Rich Nute [ mailto:ri...@sdd.hp.com <mailto:ri...@sdd.hp.com> ] Sent: Wednesday, August 01, 2001 4:30 PM To: keh...@lsil.com Cc: emc-p...@majordomo.ieee.org Subject: Re: Mains fusing Hi Kyle: > I have a new product that includes an off the shelf UPS that is rated for > 230V ac operation and has an internal single pole circuit breaker on the > mains inlet. We want to target this product world-wide. The UPS presently > is CB and certified to EN60950 european only. For North America we want it > to have UL1950, and to obtain this, UL is demanding the breaker be double > pole. This is an unusual situation. On the one hand, the UPS, with single-pole overcurrent protection, has a CB to EN 60950 for use in Europe where most mains supply plug configurations are non-polar. There is no control that the overcurrent protection will be in the live conductor. On the other hand, the UPS, with single-pole overcurrent protection, is denied UL certification for use in the North America where UL requires polarization of both the UPS overcurrent protection and the mains supply plug configuration. There is a reasonable control that the overcurrent protection will be in the live conductor. There is indeed something wrong with this picture. My guess is that the certification engineer is invoking Table 1, Case B (UL 1950, 3rd). (As someone had already suggested, you should verify this with your certification engineer.) Probably, this is because he knows that you are marketing your product worldwide. Since you have a CB, you are qualified for Case B independent of your UL certification. You should point this out to your certification engineer. I would ask UL to investigate the product under Case A. UL can, at its discretion, investigate products to specific provisions of their standard. UL can invoke paragraph D of the UL foreword to the standard. You can even ask UL to so note this construction in the UL report. In my experience, these proposals should get you around this situation. If you are still unable to use the single-pole overcurrent protection, I would go to another NRTL. Good luck, and best regards, Rich ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
