I have an thermocouple problem.
Background: I have two test/measurement setups that are measuring the same phenomona. I am using the same thermocouple harness in both setups. This harness comprises of 8 K-type thermocouples paralleled for averaging. By shooting a signal into the connector for the harness, we calibrated the system. The harness was verified (for function) earlier. It checks out to w/in tenths of a degree F. The thermocouples typically read between 800-1500F. The connector heats up to about 400F (give or take about a 100F).
Problem: I am loosing about 8 degrees F from one setup to another. I tend to believe the 8 degrees..
Any ideas?
Also, any recomendations for a good book or something (in addition to Omega's stuff) for learning about thermocouples. I understand the basics about Seebeck, but it is still voodoo chemistry to me. How do you model such circuits. How would you model a short to a known medal kinda stuff. That 8 TC harness in parallel would be nice to understand.
thanks
-josh