Copper-constantan thermocouple.

Hi Peter,

understandung the Seebeckeffect helps to understand that the junction only have to be electric conductive. all other doesn't matter.

Marte

Good thermocouples use special cables that have wires made of copper and constantan, to avoid having extra joints in the way to the electronics. You don't need to weld them, even twisting together the wires of the cable creates a sensor, and it works.

Some multimeters have a scale to measure temps with a thermocouple, and the proper socket.

Notice that the setup actually has two joints, one at the sensor and another (same loop) at the electronics board. The thing measures temperature differences between the two joints, so there is another type of sensor (ex.: thermistor) near the second joint. Think that the constantan wire has to join the electronic board metals at some point.

My experience (old) is with sensors and measurements. The setup used in heaters is different.

Sometimes we had failures and the answer was to replace sensor or cables. We did not study why they failed. We just tried a spare sensor, and if it worked, problem solved. We had a bunch of them. Once we had the vendor give us a lecture :-)

Seen in marketing publications but don't have one.

In the setup here, the second connection would be inside the Cal Controls 3200 which I haven't opened. Wikipedia refers to the "reference junction".

Thanks, ... P.