Thank you for all your answers related to my question. I' ve got good ideas for this area and I appreciate your time and kindness to do it.
Best wishes and Happy New Year to all of you! Regards, Carmen Filimon Leitch Canada > -----Original Message----- > From: Alexandru Guidea [SMTP:gui...@cae.com] > Sent: Tuesday, January 08, 2002 8:57 AM > To: 'Carmen.Filimon'; 'EMC Forum' > Subject: RE: SMPS Derating reqs for Altitude range of 5000-10000ft > Importance: Low > > As mentioned by some colleagues in this forum, some thermal effects due to > altitude are caused by reduced air density, which decreases the heath > dissipation through convection. > The percentage of heath dissipation by convection depends of the > construction of each power supply (I don't believe most of the > manufacturers > are able to provide a number there). For terrestrial application, the > convection being the dominant path, anything above 50% can be a good > guess. > By determining the density of the air at a given altitude versus "normal > operating level" it can be determined the impact on convection, and > ultimately the derating of the PS. > To be noted that: forced air, or natural convection cooling processes are > not affected the same way; PS' working in uncontrolled environments at > high > altitude can be affected by low ambient temperatures. > And as a final note, sometimes the experiment is the fastest, easiest way. > > Alexandru Guidea > > CAE Inc. > Canada > > (my opinion and only mine) > > > -----Original Message----- > From: Carmen.Filimon [mailto:carmen.fili...@leitch.com] > Sent: Friday, January 04, 2002 11:28 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.
