Thermal resistance type temperature sensors are designed by using metal resistance with temperature changes. The use of thermal resistance to make temperature sensors is mainly due to higher stability and accuracy. Common thermal resistances are platinum resistance and copper resistance. The relationship between resistance and temperature of most metals is:
Rt = R0 [1 + α (t-t0)]
The thermal resistance temperature sensor materials are divided into temperature sensing materials, protective materials and insulating materials. In addition to platinum and copper, the temperature-sensing materials include nickel, iron, and tungsten. The protective material is the protective sleeve. Stainless steel, carbon steel, copper alloy, ceramics, quartz, etc. are often selected, which is mainly used in the environment of oxidation, corrosion and high temperature. Insulation materials are mainly ceramic and organic materials. Ceramic materials can be used at 500 degrees Celsius. Organic materials can only be used at 250 degrees Celsius, otherwise the insulation performance will be reduced.
The measurement error of thermal resistance includes the error of introducing R0, the error of the index table of the thermal resistance, the error caused by the self-heating effect, the error of its own stability, the error caused by insufficient insulation, the error of the lead and the dynamic response error, etc. Some of them are system errors and some are measurement errors. Try to reduce the corresponding error value according to the actual situation.