Brief introduction of temperature sensor

Brief introduction of temperature sensor

Temperature transducer is a kind of sensor which can sense temperature and convert it into usable output signal. Temperature sensor is the core part of temperature measuring instrument, which has many kinds. According to the measurement method, it can be divided into contact type and non-contact type. According to the characteristics of sensor materials and electronic components, it can be divided into two categories: thermal resistance and thermocouple.

Resistance sensing

With the change of temperature, the resistance of metal also changes.

For different metals, when the temperature changes by one degree, the resistance value changes differently, and the resistance value can be directly used as the output signal.

There are two types of resistance variation

Positive temperature coefficient

Temperature rise = resistance increase

Temperature decrease = resistance decrease

Negative temperature coefficient

Temperature rise = resistance decrease

Temperature decrease = resistance increase

Thermocouple sensing

The thermocouple consists of two wires of different materials, which are welded together at the end. If the ambient temperature of the unheated part is measured, the temperature of the heating point can be accurately known. Because it must have two different materials of conductor, it is called thermocouple. Thermocouples made of different materials are used in different temperature ranges, and their sensitivities are also different. The sensitivity of thermocouple refers to the change of output potential difference when the hot spot temperature changes 1 ℃. For most metal supported thermocouples, this value is between 5 and 40 microvolt / ℃. 

Because the sensitivity of thermocouple temperature sensor has nothing to do with the thickness of material, it can also be made of very fine material. Because of the good ductility of the metal material used to make the thermocouple, this kind of tiny temperature measuring element has a very high response speed and can measure the process of rapid change.