What are the common temperature sensors?

Date：2017-05-25 Click：5874

In the new era of rapid development,the temperature sensor becomes more and more important in industrial production, the temperature is the highest frequency of the measured physical parameters, and can use a variety of sensors to measure. All of these sensors infer temperature by detecting changes in some physical properties. It can be seen that the use of temperature sensors in industry is very extensive. So, what are the industrial temperature sensors?

1.thermocouple

It consists of two dissimilar metal wires welded together to form two junctions. The temperature difference between the nodes will generate thermoelectric potential between the two wires. The temperature of the detecting node can be deduced by holding the reference node on the known temperature and measuring the voltage. The advantage of thermocouple is that the working temperature range is very wide, and the volume is very small. However, they also have the disadvantages of small output voltage, easy to suffer from noise from the wire loop and higher drift.

2.resistance thermometer

It is a coil or film spiral tube which can display the resistance value as the temperature changes. Although the commonly used metals are copper, nickel and nickel iron alloy, the RTD made of platinum has the best linearity, repeatability and stability. With its excellent linearity and unparalleled long-term stability, platinum RTD firmly established its position as the international standard for temperature reference transmission. Although thin film platinum RTD provides performance matching, standard wirewound resistors are superior in cost, size and convenience. The early thin film platinum RTD was plagued by drift because of their high surface area to volume ratio, which made them more sensitive to pollution. Later, the improvement of film isolation and packaging eliminates these problems, which makes the film RTD exceed the wire winding resistance and NTC thermistor at one time and become the preferred temperature sensor.

3.thermistor

It consists of metal oxide ceramics, and it is the lowest cost and most sensitive temperature sensor. At the same time, they are also the worst linear temperature sensors with negative temperature coefficients. Usually, two thermistors are used together to make the output have better linearity. Although it provides accurate interchangeability of 1%, the cost is often higher than that of platinum RTD. The conventional thermistor exhibits a good resistance stability at a limited operating temperature range and exhibits moderate stability over a wide range of temperatures.
As we know, the three temperature sensor is the most commonly used thermocouple, resistance thermometer and NTC thermistor with three kinds of commonly used temperature sensors constantly use industrial production in the industrial process, which is part of the practical technology, exactly what kind of? According to the actual situation of the project to make a choice, so that it can make the temperature sensor better service industrial production.