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3887 Views 3 Replies Latest reply: Jun 29, 2014 8:59 PM by boborrob RSS
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Jun 17, 2014 10:31 PM

Proper Wire for Thermocouple Connection

Hi guys, I'm working on a project which includes monitoring the temperature of 90gallon tank and controlling it with a PID. I just have a quick question, for me to be able to extend the length of the thermocouple, can I use just simple copper wire toward the female plug (coming from the PID) or do I have to use the same thermocouple wire?

 

I believe that the junction at which the two wire meet is where the magic happens, so it wouldn't matter what I use as an extension? Am I right?

  • boborrob Novice 45 posts since
    Apr 4, 2014
    Currently Being Moderated
    Jun 18, 2014 11:21 PM (in response to JohnDavis)
    Proper Wire for Thermocouple Connection

    You can connect any wire for that. The heat detection properties of a thermocouple is found at the junction of the two different metals. Everything else is just to carry voltage that the junction produces due to The Seebeck effect.

    • Grammy Novice 1 posts since
      Jun 29, 2014
      Currently Being Moderated
      Jun 29, 2014 11:04 AM (in response to boborrob)
      Proper Wire for Thermocouple Connection

      You have to be careful here. In some cases you have to use cable with the same makeup as the thermocouple, and in others you can use what is called compensating cable. If you don't, you are just creating another thermocouple connection (metals of dissimlar type), creating another thermocouple junction. Every time you make a connection of unlike metals, you create a new junction, and you start getting an average or spurious readings of all the junctions. I would suggest you look deeper & contact an instrument manufacturing company for further info. Many of them would have applications manuals etc.. Also you may find further info from component suppliers with temperature controllers in their catalogues.

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