The key point in these measurements is assuring compliance with the temperature limits of the standard. If you have measurements so close the conduction of heat down the thermocouple wire is making you fail, it's time to take a closer look at the product. If agency inspectors are giving you a hard time about thermocouple construction, you probably have a bad relationship with them. Readings which are consistent and predictable should be quite dependable. If all your thermocouple readings start together at ambient you're pretty assured they are OK. Your biggest risk is wires shorted other than at the junction or dislodged/ misplaced thermocouples. I have been able to justify the use of thermal crayons, infrared imaging and touch provided measurement tolerance was taken into account. Be willing to argue your point with the inspector if necessary. Bob Johnson
Ralph McDiarmid wrote: > I say that the voltage is generated at the junction of the wires, but the wires should conduct some heat away from the junction. I expect that the error is typically small, but it and other effects (like air flow and bead-to-surface bonding) might produce an error on the order of a few degrees C. > > > Ralph McDiarmid, AScT > Compliance Engineering Group > Xantrex Technology Inc > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
