Thermocouple card

tkhawkin

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T
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Jul 2010
Location
South Carolina
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I set up a temperture controller, It works fine now I need to test the thermocouples. What I need to know is, the wire from the test meter to thermocouple the same on a K type and a J type. Thanks
 
I was under the impression that thermocouple wire IS the thermocouple itself; Joining the two creates a small potential.
 
Correct, but connecting copper wires to the thermocouple wires creates 2 more thermocouples, giving a total of 3 in series. Thermocouples must be connected with thermocouple extension grade wire and associated connectors to eliminate this.
We must use the same metals for the entire run back to the electronics. At the electronics (terminal block) end, we do have the unavoidable problem of 2 more thermocouples. This is called the Cold Junction. A temperature sensor is added. It senses the temperature of the Cold Junction, and subtracts it from the reading. The net is the reading of the thermocouple we want - the Hot Junction.
See this well written paper from Omega.
 
Last edited:
a thermocouple is two different types of wire connected. so no they are not the same.

testing is simple.
use a short copper wire and the result should be the surrounding temp.
use a thermocouple wireset and twist the end. making an electrical connection.
now connect the two wires and heat the other end up.
 
keithkyll said:
At the electronics (terminal block) end, we do have the unavoidable problem of 2 more thermocouples. This is called the Cold Junction. A temperature sensor is added. It senses the temperature of the Cold Junction, and subtracts it from the reading.
Click to expand...
CJ reading gets added to the EMF reading/conversion, not subtracted.
 
Hi All, since it is discussing about the thermocouple, i got some issue on this.

I'm using Delta PLC and DVP04TC module, i just cant read the temperature, everything show K0. Please help.

I used the template, it doesn't work.
 

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