THE Thermocouple temperature sensor owes its success to its great versatility. It allows you to create Thermal probes Suitable for many areas of application. The operation of thermocouple is based on a phenomenon called Seebeck thermoelectric effect. We deduce the temperature from the level of electrical voltage generated by the temperature change within the thermocouple.
The operation of thermocouples is based on thermoelectric voltage
A thermocouple is a temperature sensor Used in various fields (industry, chemistry, food, etc.). It contains two metal wires of different natures.
The operating principle of thermocouples
These sons are connected by two welds, the hot spot and the cold point. There hot welding is often protected by a metal sheath. The cold point must remain at a known temperature. During the temperature taking, Cold welding can be maintained at a specific temperature via a refrigeration mechanism.
When the hot spot is exposed to heat or cold, Electronic density of each thread is modified. We use measurement equipment for Evaluate the electro-motor force and thus measure the temperature.
The precautions to be taken for optimal thermocouples operation
Metal wires must be welded properly to withstand vibes. Several junction techniques exist, such as electric weld. The welding temperature should be checked to avoid damaging the wires.
THE electrical interference can disrupt the thermocouple signal. A noisy motor nearby can distort the results, requiring recalibration.
It is essential to use The good type of thermocouple and a Adapted sheathing In the middle to measure. A decaling may occur due to too high temperature or wear of the sheath.
How to choose thermocouple?
The temperature range and the response time
In theory, Several metal alloys Can be used to form a thermocouple. There is 8 types of thermocouples commonly used. The J, K, T and E types are economical and versatile. The types R, S and B allow Measure very high temperatures.
The choice of thermocouple must correspond to the temperature range to measure. For optimal precision, it is necessary Adapt the temperature range From sensor to application.
THE response time depends on the type of junction. A Junction exposed Allows a faster reaction, because it is not protected by a sheath.
Compatibility with the field of application
When choosing a temperature sensor, it is important to define the variables to be measured. For example, a humidity and temperature sensor can be useful. A programmable transmitter Allows you to configure the parameters depending on the application.
A good electronic sensor should be easy to handle and adapted to the environment. Some devices combine infrared and thermocouple thermometer for a distance measurement.
Among the most used sensors, we also find the thermist, which react to temperature variations by modifying their resistance.
