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Some Questions about Thermocouple and Resistance Temperature Sensor

1.What is the measuring principle of thermocouples?
The working principle of the thermocouple is based on Seebeck effect. That is to say, two conductors of different components are connected at both ends into a circuit. If the temperature of two terminals is different, the physical phenomenon of heat current in the loop will be generated. The thermocouple is composed of two different conductors (thermal electrodes), one end of which is welded to each other to form the measuring end of the thermocouple (also known as the work terminal), inserting it into the medium whose temperature is to be measured, and making sure the other end of the thermocouple (the reference end or the free end) is connected to the display meter. If there is a temperature difference between the measuring end of the thermocouple and the reference end, the meter will indicate the thermoelectric force produced by the thermocouple.

2. What is the measuring principle of resistance temperature sensor?

Resistance temperature sensor is used to measure the temperature according to its characteristics that metal conductors or semiconductors with temperature change drive the resistance itself to change as well. The heating part of the resistance temperature sensor (the temperature sensing element) is formed on the substrate by uniformly winding the thin metal wire on the framework of the insulating material or by the laser sputtering process. When the measured medium has a temperature gradient, the measured temperature is the average temperature of the dielectric layer within the range of the temperature sensing element.

3. How to choose thermocouple and resistance temperature sensor?

According to the temperature range: generally speaking, choosing thermocouple when the temperature is over 500℃, on the contrary, choosing resistance temperature sensor;

According to the measurement accuracy: choosing resistance temperature sensor to meet higher accuracy requirements, on the contrary, choosing thermocouple;

According to the measurement range: thermocouple generally measures "point" temperature while resistance temperature sensor usually measures spatial temperature;

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