The PT100 temperature sensor is also called platinum thermal resistance. The platinum thermal resistance is the most commonly used temperature detector in the low temperature zone. Its main features are high measurement accuracy and stable performance. Among them, the PT100 temperature sensor (platinum thermal resistance) has the highest measurement accuracy, and it is not only widely used in industrial temperature measurement, but also made into a standard reference instrument. The temperature sensing element of the metal thermal resistance has a quartz casing cross skeleton structure, a twisted skeleton structure and a rod structure. Metal thermal resistors commonly use a variety of temperature sensing materials, the most commonly used is platinum wire. In addition to platinum wire, there are copper, nickel, iron, iron-nickel, tungsten, silver, etc. in addition to platinum wire. The film thermal resistance is manufactured by means of electron cathode sputtering, and can be industrially mass-produced. The skeleton is made of ceramic, and the lead is made of platinum-palladium alloy.

The principle of temperature measurement of the thermal resistance is different from the temperature measurement principle of the thermocouple. The thermal resistance is based on the thermal effect of the resistance, that is, the resistance of the resistor changes with temperature. Therefore, as long as the resistance change of the temperature sensitive resistor is measured, the temperature can be measured. At present, there are mainly two types of metal thermal resistance and semiconductor thermistor.

At present, the most widely used thermal resistance materials are platinum and copper. The platinum resistance is high. It is suitable for neutral and oxidizing media. It has good stability and has certain nonlinearity. The higher the temperature, the smaller the rate of change of resistance. The copper resistance is measured. The resistance value and the temperature are linear in the temperature range, and the temperature line is large, which is suitable for non-corrosive media, and more than 150 is easily oxidized. The most commonly used in China are R0=10Ω, R0=100Ω and R0=1000Ω, and their index numbers are Pt10, Pt100, Pt1000 respectively; copper resistors are R0=50Ω and R0=100Ω, their indexing The numbers are Cu50 and Cu100. Among them, Pt100 and Cu50 are the most widely used.