Brian brings up a good point. Where is the best place to put the thermocouple.
If the location is critical, we use two methods; one is a touchless thermometer. These are cheap. Less than $25 at most places like Harbor Freight. You are only looking for the hot spots. Method #2 is we go borrow the thermal imaging camera from R&D. We can quickly locate the hot spots and mark it with a Sharpie. Then glue the thermocouples at those locations. As the cost of thermal imaging cameras are coming down, we are hoping to buy our own very soon. The Other Brian -----Original Message----- From: Brian O'Connell [mailto:oconne...@tamuracorp.com] Sent: Friday, February 26, 2016 12:11 PM 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> ________________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - ---------------------------------------------------------------- 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>
