Generally agree, but be careful with using a spray-type application for the accelerant. Prefer to use an eye dropper. Had a tech, while doing tests for UL5085-3, that caught a small linear transformer on fire because the (very volatile) accelerant had not completely evaporated after spray application, and had been applied over a 2x2cm area.
Thermal paste, by itself, can be adiabatic (may actually expand to insulate), and is essentially a contaminate unless compressed between two parallel surfaces. Should never be used around TCs for type tests. Cured cyanoacrylate is essentially diabatic. The glue line must be very thin, and must hold the TC bead in firm, static mechanical contact with the component. Wrote a tutorial about thermal test technique and error sources about 10 years ago, that showed up at two NRTLs, but was never accepted by the IEEE PSES. Should be sitting somewhere on one of the servers, will try to find it. Of course the best accelerant for TC adhesives are the tears of the sales and marketing directors. Brian -----Original Message----- From: Kunde, Brian [mailto:[email protected]] Sent: Friday, February 26, 2016 9:13 AM To: [email protected] Subject: Re: [PSES] Reliable means to attach thermocouple to object Scott, Year ago we used Tac Pac with a spray accelerator. Just place a dab of glue where you want it, insert the thermocouple, then spray it with the accelerator and it would instantly harden. To remove, we used some kind of solvent (acetone?). Just a drop would start to soften the glue and within 30 seconds you could pull the thermocouple out for re-use. I don't recall the product numbers but a little research should find them easy enough. I think it was something like Loctite 444 adhesive with accelerator kit. The accelerator was 7452 and came either in a small spray can or in a bottle. There are probably new formulas today that work just as good. Some glue the thermocouple up slightly from the end and then use thermal paste on the end. It is messy and we didn't really see much difference in our test results. The Other Brian -----Original Message----- From: Scott Xe [mailto:[email protected]] Sent: Friday, February 26, 2016 11:53 AM To: [email protected] 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
