Industrial thermistorIt is a commonly used temperature detection sensor in the low temperature zone of the industrial field, based on the characteristic of the resistance value of metal or semiconductor materials changing with temperature to achieve temperature measurement. The core principle is that as the temperature increases, the internal lattice vibration of the material intensifies, leading to enhanced electron scattering and an increase in resistance value (such as positive temperature coefficient materials like platinum and copper); Some semiconductor materials exhibit negative temperature coefficient characteristics. This physical characteristic makes it a core component for high-precision temperature measurement in the range of -200 ℃ to 850 ℃.
Industrial thermistorThe main characteristics are:
1. High precision and high stability
High precision: Industrial thermistors (especially platinum resistors Pt100/Pt1000) have very high temperature measurement accuracy. For example, the allowable error of APt100 compliant with IEC 60751 standard at 0 ° C is only ± (0.15+0.002 | t |) ° C.
Long term stability: Under normal usage conditions, its resistance temperature relationship is very stable, with minimal annual drift, making it suitable for situations that require long-term reliable measurement.
2. Wide temperature measurement range
A typical industrial platinum resistance (Pt100) typically has a temperature measurement range of -200 ° C to+850 ° C.
By selecting different protective tube materials (such as stainless steel, high-temperature alloys, ceramics), it is possible to adapt to various working conditions from deep cold to high temperature.
(Note: Copper resistors Cu50/Cu100 have a narrow range of about -50 ° C~+150 ° C and are less commonly used.)
3. Good linearity of output signal
Platinum resistors exhibit an approximately linear relationship between their resistance and temperature over a wide temperature range, following the Callendar Van Dusen equation.
Advantages: Good linearity means simple signal processing, easy calibration and compensation, and intuitive and reliable measurement results.
4. Good repeatability
The same thermistor has highly consistent measurement results for the same temperature point in multiple temperature rise and fall cycles, with excellent repeatability, ensuring the reliability of the measurement.
5. Strong anti-interference ability
Thermistors output resistance signals (or converted into voltage/current signals), which have stronger resistance to electromagnetic interference (EMI) compared to the microvolt level voltage signals of thermocouples. They are particularly suitable for industrial use in strong electromagnetic environments such as motors and frequency converters.
6. Sturdy structure and high reliability
Industrial thermistors are usually composed of temperature sensing elements (platinum wire/film), insulation materials, protective tubes, and junction boxes.
Protective tube: Made of stainless steel (such as 304, 316L), high-temperature alloys (such as Inconel 600), ceramics and other materials, it can effectively resist mechanical damage, chemical corrosion and high pressure.
Overall design: Compact structure, good sealing performance (high IP rating), capable of long-term stable operation in harsh industrial environments.
7. The response time is relatively slow
Main disadvantages: Due to the contact temperature measurement and the temperature sensing element being encapsulated in a protective tube, its thermal response time is slower than that of a thermocouple.
Influencing factors: The response time depends on the material of the protective tube, wall thickness, diameter, and whether it is equipped with a sleeve. Response speed can be accelerated by selecting small-diameter, thin-walled protective tubes or exposed end (partially exposed) designs.
8. External excitation power supply is required
Thermal resistance itself is a passive device that requires a constant excitation current (usually 1mA) from the outside to measure its resistance value.
This means that measurement systems (such as transmitters, PLC modules) must have power supply functionality.