K-type thermocouple, the meaning of electric potential value
Thread Content
I have a few questions to ask for confirmation.: 1. Is the reference temperature in the graduation table the ambient temperature? If so, assuming the ambient temperature is 20°C and the temperature at the detection point is 5°C, then the potential values of the positive and negative electrodes are negative, right? Only when the temperature of the detection point is higher than 20℃, the potential value is positive, right? It’s best expressed with a formula. Thank you. 2. The problem with the material of the K thermocouple itself is that the negative electrode of the K-type thermocouple is nickel silicon, which can be absorbed by the magnet. ； And the positive electrodes are all nickel-chromium, non-magnetic? What about the compensating wire? What material is it made of? Are the magnetic properties consistent with the positive and negative poles of the thermocouple?
1. The reference temperature in the graduation table is 0 degrees. When the hot end temperature is lower than the cold end temperature, the thermoelectric potential is negative. 2. The negative electrode of K-type thermocouple is nickel silicon, which can be absorbed by magnets. ； The positive electrode is nickel-chromium, which is non-magnetic. Compensation wires can be selected from iron-copper-nickel 22 (KCA), copper-copper-nickel 40 (KCB), and nickel-cadmium 10-nickel silicon 3 (KX) types.
If the compensation wire is Nickel Cadmium 10-Ni Si 3 (KX) type, then the negative pole of the thermocouple and the compensation wire are magnetic, and the positive pole is non-magnetic? If it is iron-copper-nickel 22 (KCA) or copper-copper-nickel 40 (KCB), can it be seen with the naked eye that the copper-containing end turns yellow?
What about thermocouple experts? I need help. Still have questions
1. E(t, 0) = E (t, t1) + E (t1, 0) The reference temperature of the potential value in the thermocouple indexing table is 0°C, that is, E (t, 0). t in the formula is the temperature of the measuring point, which is the 5°C you mentioned, and t1 is the cold end temperature, which is the 20°C you mentioned. Under normal circumstances, what we measure is E (t, t1), and t1 is generally not 0°C. The thermocouple graduation value in the graduation table increases with the increase of temperature, that is, E (20, 0) > E (5, 0) Therefore, E(5,20)=E(5,0)-E(20,0)<0, which is a negative value 2. The compensation wire must be consistent with the model of the thermocouple. The K-type compensation wire corresponds to the K-type thermocouple, and the E-type compensation wire corresponds to the E-type thermocouple. And the positive electrode corresponds to the positive electrode, and the negative electrode corresponds to the negative electrode. The compensation wire moves the cold end.