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How to judge whether the thermocouple is good or bad?


The use in production is becoming more and more extensive. Thermocouples have become one of the most commonly used temperature detection components in the industry. They have the characteristics of high measurement accuracy, wide measurement range, simple structure, and convenient use. We understand and analyze products through multiple channels, and present a wide range of industry knowledge to the majority of netizens.
So next we come to understand the judgment of whether the thermocouple is good or bad?
The basic principle of thermocouple temperature measurement is that two different components of material conductors form a closed loop. When there is a temperature gradient at both ends, current will flow through the loop. At this time, there is an electromotive force-thermoelectromotive force between the two ends. This is the so-called Seebeck effect. Two homogeneous conductors of different components are thermoelectrodes, the end with a higher temperature is the working end, the end with a lower temperature is the free end, and the free end is usually at a certain constant temperature.
After using for a period of time, thermocouples will definitely wear out, and may even be damaged. Generally, the quality of thermocouples is related to the thermocouple wire (wire) in it, but how to judge the quality of the thermocouple wire is the problem. Let's discuss it briefly.

First of all, make sure that there is no problem with the appearance of the thermocouple wire, whether it is good or bad, and it can only be determined by testing.
Put the thermocouple wire to be tested on a special ceramic sleeve for the thermocouple, and put it into the tubular electric furnace together with the standard platinum and rhodium thermocouple, and insert the hot end into a porous soaking metal nickel in the tubular electric furnace. In the cylinder. Put the cold ends of the respective compensation wires into a container at zero degrees Celsius maintained by a mixture of ice and water.
Keep the electric tube furnace at the maximum allowable temperature of the thermocouple, and keep this range steadily. At this time, use a qualified Wheatstone potentiometer to measure and record the thermoelectric potential difference between the standard thermocouple and the thermocouple to be tested. According to the recorded thermoelectric potential difference, check the index table to find out the corresponding temperature. If the thermocouple under test is out of tolerance, it can be judged as unqualified.