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Industrial automation » Sensor » Temperature Sensor

Temperature Sensor

To measure the temperature, a temperature sensor is needed, which according to the range and method of measuring the temperature, different temperature sensors are used. Temperature sensors are divided into several general categories, which are noted below:

1- silicon bandgap temperature sensor

This example of silicon temperature sensors, which have a good stability for measuring ambient temperature due to the stability of crystallized silicon, are mostly used in electronic equipment and at a very low price for various applications in the temperature range of minus 30 to 125 degrees Celsius with an accuracy of one They are used up to two degrees and their millivolt output increases with each degree of increase.

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2-Thermistors

Thermistors are another common and inexpensive temperature sensors that are based on changing the resistance of ceramic and polymeric materials and are classified into two groups: PTC and NTC.

The resistance of the PTC thermistor or temperature sensor decreases with increasing temperature and in NTC thermistors. The temperature range of the thermistor temperature sensor can be from minus 90 to 130 degrees and NTC is used in most refrigerators.

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3- Resistance temperature detectors (RTDs) یا Thermo Resistance

Thermoresistance or RTD are a more industrial example of precision temperature sensors that are widely used in industry. Although the mechanism of temperature measurement in thermorescences is the same as that of thermistors and they work based on resistance to changes in temperature, but thermoresistors are made of very thin filament wires of high purity metals such as platinum, nickel, and copper and have more accuracy and suffering. They are wider.

These thin wires are usually wrapped in a piece of ceramic or glass and because the wires are hairy, they must be covered with materials. The most famous example of RTD temperature sensors in the industry is PT100, which shows a resistance of 100 ohms with a positive temperature coefficient of zero degrees Celsius, and with increasing temperature, the resistance increases in a predictable and linear manner.

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4- Thermocouple

Thermocouple is the most important industrial temperature sensor and is widely used in industry due to its simple mechanism and coverage of a wide range of temperature ranges. The basis of the thermocouple is the production of voltage at the junction of two homogeneous metals due to heating. High reaction speed and acceptable accuracy as well as the possibility of measuring high temperatures up to 1700 degrees are the main reasons for using thermocouples in various industries.

Thermocouple temperature sensors are more common in types K, T, J, E, R, S, B and are made and calibrated from different alloys depending on the measuring range.

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5- Infrared temperature sensor

Infrared temperature sensors, such as infrared or non-contact thermometers, work with heat radiation called blackbody radiation. Temperature sensors are also called lasers. The advantages of these sensors are very high reaction speed and usability for very high temperatures.


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