Basic principle of thermocouple spot welding head

The basic principle of thermocouple spot welding head it that to kind of  materials conductor with different components form closed loop.When there is a temperature gradient at both ends, there will be current passing through the loop. At this time, there will be electromotive force- EMF between both ends, which is the so-called Seebeck effect. Two homogeneous conductor with different components are hot electrodes, one end with higher temperature is the working end, and the other end with lower temperature is the free end. The free end is usually at a constant temperature.

When the third metal material is connected to the thermocouple circuit, as longs as the temperature of the two contacts of the material is the same, the thermoelectric potential generated by the thermocouple will remain unchanged, that is, it will not be affected by the third metal connection circuit. Therefore, when the thermocouple spot welding head is used for temperature measurement, the measuring instrument can be connected to know the temperature of the measured medium after the thermoelectromotive force is measured. When measuring the temperature , the thermocouple require that the temperature of its cold end ,( the measuring end is the hot end), and the end connected to the measuring circuit through the lead wire is called the cold end) remain unchanged, the thermoelectric potential has a certain proportional relationship with the measured temperature. If the temperature of the cold end( environment) changes during measurement, the accuracy of measurement will be seriously affected. If the measurement takes certain measures at cold end to compensate the influence caused by the temperature change at the cold end, it is called that the cold end compensation of thermocouple is normal. Special compensation wire for connection with measuring instrument.

Thermocouple spot welding head is a temperature sensing element and a primary instrument. Thermocouple directly measures temperature. The closed loop composed of two kinds of conductors with differnt compositions produces electron diffusion due to different materials, and electric potential is generated after stable equilibrium. When there is gradient temperature at both ends, current will be generated in the loop, generating thermoelectromotive force. The larger the temperature difference, the larger the current will be. After measuring the thermoelectromotive force, you can know the temperature value. Thermocouple is actually a kind of energy converter, which can convert thermal energy into electrical energy.

Technical advantages of thermocouple spot welding head: Thermocouple temperature measurement range is wide, performance is stable; High precision, thermocouple is in direct contact with the measured object, not affected by the the intermediate medium; The thermal response time is fast, and the thermocouple has flexible response to temperature changes; The measurement range is large is large, and the thermocouple can continuously measure temperature from 40～+1600℃; The thermocouple has reliable performance and good mechanical strength. Long service life and convenient device.

The conductors or semiconductors A and B of two different material are welded together to form A closed loop.When there is a temperature difference between the two attachment points 1 and 2 of the conductors A and B, an electromotive force will be generated between the two, thereby forming a large current in the loop. This phenomenon is called the thermoelectric effect. Thermocouple use this effect to work.