The difference between the working principle and use of thermocouple sensor and thermal resistance

With the acceleration of industrial development, the use of thermocouples in chemical industry is constantly expanding. Thermocouples are already the first among the most commonly used temperature detection tools in industrial production. It is characterized by high measurement accuracy and measurement range. Wide, simple structure, easy to use and so on. We understand and analyze products through various channels, and bring professional industry introductions of various thermocouples to our customers. We will tell you the difference between the working principle and use of thermocouple sensor and thermal resistance. The temperature sensor, like thermal resistance, is a temperature sensor, but there are still some points in the process of using thermocouple and thermal resistance. the difference. 1. The difference between signals: the thermal resistance itself is a resistance, and the thermal resistance thermometer works according to the principle that the resistance of the wire changes with temperature; and the thermocouple: two wires or semiconductors of different materials are welded together to form a closed loop , When there is a temperature difference between the two contacts of the wire, an electromotive force is generated between the two, thus forming a certain amount of current in the loop, which is called the thermoelectric effect. Thermocouples use this effect to work. 2. The temperature range detected by the two sensors: the thermal resistance generally detects the temperature range of 0-150 degrees, and the highest measurement range can reach about 600 degrees, while the thermocouple can detect the temperature range of 0-1000 degrees (or even higher). 3. Material cost: The thermal resistance is a metal material with temperature-sensitive changes. The thermal resistance is a resistance signal, and its output is the resistance value (Ω), without positive and negative poles. Commonly used are Pt100, Cu50. . The thermocouple is a bimetal material, that is, two different metal materials, due to the change of temperature, a potential difference is generated at both ends of the two different metal wires. It can be divided into K, S, E, R, T, N and other graduation numbers, which can be used in different measurement media and temperature measurement ranges respectively. A thermocouple is a voltage signal, and the output is a millivolt value (mV), with positive and negative poles. Some are more expensive than resistors, and some are cheaper than resistors, but the comprehensive cost of thermocouples is higher when the compensation wires are included. 4. Relationship with PLC: The input modules of the thermal resistance and the thermocouple corresponding to the PLC are also different. This sentence is no problem, but generally the PLC is directly connected to the 4-20ma signal, while the thermal resistance and the thermocouple are generally Only connect to PLC with transmitter. If you connect to DCS, you don't have to use a transmitter. Thermal resistance is RTD signal, thermocouple is TC signal! (PLC also has thermal resistance module and thermocouple module, which can directly input resistance and galvanic signals.

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