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Thermocouples - Misreadings

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Thermocouples - Misreadings

Postby Guest » Thu Mar 05, 2009 10:14 am

Hi there,
I am using a Chromel-Alumel thermocouple to measure the temperature across a strip of metal. It has come to my attention that at the point of contact between the two there is an unwanted temp drop. How exactly does this affect the thermocouple? (apart from my extropolated temps being higher than what they should be??) ANy help in explaining this would be greatly appreciated

Postby ziko » Fri Mar 06, 2009 4:33 pm

Hi are the thermocouples connected the wrong way round? If so then it could be that your temperature difference between your source and cold junction is being subtracted instead of added to the cold junction temperature.

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Postby Guest » Mon Mar 09, 2009 12:19 pm

Sadly no. The connections are prechecked by technicians prior to experiment. Basically i'm experimenting the well known Stefan's Laws and i get a T^5 relationship consistently. I did read that it is well known that conduction occurs on the thermocouple but i don't understand why the temp difference would occur.
Thanks for the reply btw

Postby Guest » Sat Mar 21, 2009 2:30 pm

Ah! Anyone have any ideas on how i could calculate the heat loss by the Thermocouple?

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