>From the Paschen curve, the electrical spacings must be increased 14% at 3000 meters over those at 2000 meters. Thermal derating is a tougher call since some smps vendors engineer in more cooling capacity than others. Testing for your application is the only reliable way to make a good determination if the manufacturer does not specify a derating curve.
Daniel E. Teninty, P.E. Managing Partner DTEC Associates LLC Streamlining The Compliance Process Advancing New Products To Market http://www.dtec-associates.com (509) 443-0215 (509) 443-0181 fax -----Original Message----- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Carmen.Filimon Sent: Friday, January 04, 2002 8:28 AM To: EMC Forum Subject: SMPS Derating reqs for Altitude range of 5000-10000ft Hi All I'm trying to find out what the specified operational altitude range(s) is (are) for power supplies (particularly switching mode ones). Do any of you know what that spec may be, and particularly what is the rule for derating at altitude for thermal issues. Many manufacturers don't specify a maximum altitude but instead design in enough thermal overhead to accommodate any reasonable terrestrial location. According to GR-63-CORE the operating range without derating is 1800m above sea level. If derating is required above 1800m then the manufacturer must specify any additional requirements. Is it a safety derating factor so that customers at 5000-10000ft don't smell smoke? Do we have any recommendations for derating the operational temperature / power consumption of power supplies as the operational altitude increases? Any information or ideas you have would be appreciated. Regards, Carmen Filimon Leitch Canada > > ------------------------------------------- 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: No longer online until our new server is brought online and the old messages are imported into the new server. ------------------------------------------- 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: No longer online until our new server is brought online and the old messages are imported into the new server.
