Two different components of the conductor (called thermocouple wire or thermal electrode) at both ends of the synthesis circuit, when the temperature of two joints is different, in the circuit will produce EMF, this phenomenon is called thermoelectric effect, and this EMF is called thermoelectric potential.
Thermocouple is the use of this principle for temperature measurement, which is directly used to measure the temperature of the medium at one end is called the work end (also known as the measuring end), the other end is called which (also known as the compensation end), the cold end and the display instrument or supporting instrument connection, the display meter will indicate the thermoelectric potential generated by the thermocouple.
Thermocouple is actually an energy converter, which converts heat energy into electrical energy and uses the resulting thermoelectric potential to measure temperature, and for the thermoelectric potential of thermocouples, the following problems should be noted:
1, thermocouple thermoelectric potential is the thermocouple working end of the two ends of the temperature function difference, rather than thermocouple which and the working end, the two ends of the temperature difference function;
2. The size of the thermoelectric potential produced by the thermocouple, when the thermocouple material is uniform, is independent of the length and diameter of the thermocouple, only related to the composition of the thermocouple material and the temperature difference at both ends;
3. When the composition of two thermocouple wire materials of thermocouple is determined, the size of thermocouple thermoelectric potential is only related to the temperature difference of thermocouple. If the temperature of the thermocouple cold end remains certain, the thermoelectric potential of the thermocouple is only a single value function of the working end temperature. The conductors of two different materials or semiconductors A and B are welded to form a closed loop, as shown in the figure. When there is a temperature difference between the two persistent points 1 and 2 of conductors A and B, an EMF is generated between the two, thus forming a size current in the loop.
Thermocouples Use this effect to work.
