Kamran, As John Crabb pointed out, making measurements at different points will give you some variation due to hot spots etc. What most people miss is that thermocouple readings are affected by magnetic fields. To get a correct reading, turn power off and take a reading immidiately after the reading stabilizes. I have seen the reading change as much as 10-15 degrees when the power is turned off. Usually the reading jumps higher. I also noticed that how much the reading changes depends on where I placed the thermocouple. Usually the biggest change is when the thermocouple is placed between the core and the coil.
When trying to correlate your readings with your vendor's make sure you're using the same type of thermocouple and measure at the same point. Find out if they made the measurement with power on or off. Several years ago I had the same problem. I called the manufacturer of the thermocouple I was using. They could not tell me how much my reading would change but recommended taking the reading with power off. Hope this helps. Regards, Fred Waechter Kamran Mohajer wrote: > Hello EMC-PSTCers, > > I wonder if anyone knows of the method of measuring temperature limits on > magnetic components. I happen to get involved in this and found that my > results are different than the vendors result by as much as 10-15 degrees on > measuring on a same magnetic component. Even applying the thermocouple to > different location on a coil seems to give you different results. Is there a > method that I should be following to measure temperature with thermocouples > methods, not change of resistance, on magnetic parts such as transformers, > coils, etc.? > > Thanks, > > > *********************************************************************************** > Kamran Mohajer > DSL Compliance Lead > Cisco Systems, Inc. > Phone(408)-525-6121 > Fax(408)527-0495 > kmoha...@cisco.com > *********************************************************************************** > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > jim_bac...@monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). -- Fred Waechter Sr. Applications Engr. SMPS Consulting w...@skybest.com Phone/FAX: 336-246-5236 --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
