04/2023.05
The difference of thermocouple and RTD
1. Different Principle Thermocouple is the most widely used in temperature measurement. The principle of thermocouple is based on the thermoelectric effect, two different conductors or semiconductors are connected into a closed loop. When the temperatures at two junctions are different, the temperature in the loop A thermoelectric potential will be generated. This phenomenon is called the thermoelectric effect, also known as the Seebeck effect. Through the measurement of this thermoelectric potential, the temperature value is finally obtained. The temperature measurement principle of thermal resistance is based on the characteristic that the resistance value of a conductor or semiconductor changes with temperature. 2. Different temperature range Thermocouple has a wide range of measurement continuously from -50°C to 1600°C. Some special thermocouple can measure as low as -269°C and as high as 2300°C; the temperature range of platinum thermal resistance is generally -200°C-800°C, copper thermal resistance is -40°C-140°C. Platinum thermal resistance belongs to medium and low temperature measuring device. 3. Different types & structures 3.1. Types Thermocouple is divided into two categories: normal thermocouple and unsusal thermocouple. normal thermocouple is divided into eight different divisions, namely B, R, S, K, N, E, J and T, where B, R, S thermocouple belonging to the platinum series, because platinum is a noble metal, they are also called noble metal thermocouple, and the remaining models are called base metal thermocouple. Unsusal thermocouple is not as good as normal thermocouple in terms of range or magnitude of use, and generally there is no unified graduation table, and are mainly used for measurement in some special occasions. The common types of thermal resistance are copper thermal resistance and platinum thermal resistance. 3.2. Structures The structure of the thermocouple: The welding of the two thermal electrodes that make up the thermocouple must be firm; The two thermal electrodes must have good insulation properties to prevent short circuits, and the connection between the thermocouple compensation wire and the free end of the thermocouple must be convenient and reliable; The protective sleeve should ensure that the hot electrode is fully isolated from harmful substances. The structure of the thermal resistance: Most of them are made of pure metal materials, and the change of the resistance of various wires such as the lead wire of the thermal resistance body will affect the temperature measurement. 4. Different fields of application Thermocouple is a component whose thermal electromotive force (voltage) changes with temperature, and a thermal resistor is a component whose resistance changes with temperature. Generally, thermocouple is used in a high temperature environment, and a thermal resistor is used in a low temperature environment. If the temperature difference exceeds 500°C, the resistance v...
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