THE thermocouple is a temperature sensor Very widespread in the industry, with its versatility, its short response time and its advantageous cost. Manufacturers recommend carrying out tests throughout the life of the sensor, to ensure its good calibration. This operation involves a good understanding of the mechanisms of thermocouple. When should you test a thermocouple and in what way? We answer your questions in this detailed guide.
The operation of the thermocouple
What is the Seebeck effect?
The thermoelectric effect Seebeck is the appearance of a slight electric current in the event of a temperature variation Within an open circuit formed by two different nature metals connected at one point. This phenomenon, discovered by the German physicist Thomas Johann Seebeck in 1821, is at the source of several applications, in particular the creation of temperature measurement tools.
What is the constitution of a thermocouple?
THE thermocouple is a sensor made up of two wires of conductive metal alloys. It has two types of welds: Hot welding, or hot spot, which connects the two wires and is in contact with the environment whose temperature is measured, and the cold point, which connects each wire to the measuring device.
How does a thermocouple sensor work?
When the hot spot is exposed to a different temperature from the cold point, An electrical voltage is created in the thermocouple. This electro-motor force (FEM) depends on the temperature. The conversion between the FEM and the temperature is done thanks to conversion tables depending on the type of thermocouple.
Where do we use thermocouples?
There Thermocouple probe is a very useful temperature measurement instrument for scientific and industrial applications. It allows to perform Measures ranging from very low to very high temperatures. Its operation via a potential difference allows automated measures thanks to a recorder.
What you need to know to test a thermocouple
What is a thermocouple test?
Test a Thermocouple temperature sensor is the first step in calibration. This test checks the correlation between the electric current noted at a given temperature and the theoretical correspondence in a conversion table.
When to test a thermocouple?
The test of a thermocouple is done in several cases :
- After its manufacture and before its sale.
- In case of doubt about the accuracy of the measures.
- When changing the probe.
- Regularly, according to wear, caused by the environment.
Once the test is done on different points within the measurement range, it is possible to add a Corrective coefficient If a difference is detected.
What are the techniques to test a thermocouple?
Two main methods exist: The test by comparison And The fixed point test. The first is to compare the temperature indicated by thermocouple to that of another more precise sensor placed in the same environment. The second exhibits The hot thermocouple welding at a reference temperature, like the triple point of water (0.01 ° C).
At Thermometre.fr, The quality of our products and services is a priority. We are careful to offer prototypes and presses to test the sensors on your equipment. We benefit from ISO 9001 and ISO 14001 quality certifications.
Go further on thermocouples:
- Category of Thermocouples probes
- What are the different Types of thermocouples
- Calibration of a thermocouple
