> " ...operating at a temperature of 120 degC..." has no > meaning. Test conditions and component ID? A Tj of > 150deg does not mean that you are allowed 150deg on the > component body. TI, ST, and others have published some > good stuff on calculating component temps for power > semiconductors. That said, not unusual for normal operating > temp of some components in some SMPS to exceed 100deg. > Of course, Arrhenius had something to say about this...
For safety purposes, the only temperatures that count are the temperatures of safeguard insulations (basic, supplementary, and reinforced), and accessible parts. For years, certification houses have measured transistors, diodes, and electrolytic capacitors, but they don't count for preserving the safeguard; failure of these kinds of components do not create the possibility of electric shock or thermal burn. (Failure of these kinds of components may result in fire, but control of component temperature does not predict whether or not failure of the component will cause a fire.) Rich > -----Original Message----- > From: Brian O'Connell > [mailto:oconne...@tamuracorp.com] > Sent: Friday, February 26, 2016 9:11 AM > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: Re: [PSES] Reliable means to attach thermocouple > to object > > UL and CSA have published specific procedures and > material recommendations for T/C use in Type Tests. Most > NRTLs have some type of CIP program where a sample > power supply is sent to a company lab to verify test > technique via TRF data veracity. > > So the moral of the story is to use whatever technique that > enables NRTL/NB acceptance of your test data. In general, > cyanoacrylates are my adhesive of choice, along with > Loctite 7452, where the attachment is only for limited > number of tests. Adhesion is only half of the problem. The > other issues that must be addressed are where the t/c is > placed on the component, selection of components, and test > conditions. > > Tape is a poor choice, for many reasons, for most power > supply components. > > " ...operating at a temperature of 120 degC..." has no > meaning. Test conditions and component ID? A Tj of > 150deg does not mean that you are allowed 150deg on the > component body. TI, ST, and others have published some > good stuff on calculating component temps for power > semiconductors. That said, not unusual for normal operating > temp of some components in some SMPS to exceed 100deg. > Of course, Arrhenius had something to say about this... > > In any case, just calculate power dissipation for the diode, > then use to calc the Tj. This will be your 'sanity check'. > > Brian > > -----Original Message----- > From: Scott Xe [mailto:scott...@gmail.com] > Sent: Friday, February 26, 2016 8:53 AM > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: [PSES] Reliable means to attach thermocouple to > object > > I used to attach thermocouple to the object under > temperature rise test using Kapton tape. Currently I looked > at an SMPS that is operating at a temperature of 120 degC > under an ambient temperature of 20 degC. The tape seems > not very reliable and rigid enough for long period of testing. > Is there any other more suitable means to attach the > thermocouple to such high temperature point of interest? > > The spec quotes the max temperature of 150 degC. Is it > normal for the rectifier to have such high operating > temperature? > > Thanks and regards, > > Scott > > - > -------------------------------------------------- -------------- > This message is from the IEEE Product Safety Engineering > Society emc-pstc discussion list. To post a message to the > list, send your e-mail to <emc-p...@ieee.org> > > All emc-pstc postings are archived and searchable on the > web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online > Communities site at http://product-compliance.oc.ieee.org/ > can be used for graphics (in well-used formats), large files, > etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including > how to unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org> > David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
