Thermal resistance principle and type

Thermal resistance principle and type

Thermal resistance is one of the most commonly used temperature detectors in the medium and low temperature regions. Its main features are high measurement accuracy and stable performance. Platinum thermal resistance is the highest measurement accuracy. It is widely used not only in industrial temperature measurement but also as a standard reference instrument.

1, thermal resistance temperature measurement principle and material

Thermal resistance temperature measurement is based on the characteristic that the resistance value of the metal conductor increases as the temperature increases. Most of the thermal resistance is made of pure metal materials. At present, platinum and copper are the most widely used materials. In addition, nickel, manganese, and tantalum are now used to manufacture thermal resistors.

2, the type of thermal resistance

1) Ordinary thermal resistance

From the principle of temperature measurement of the thermal resistance, it can be seen that the change of the measured temperature is directly measured by the change of the resistance of the thermal resistor. Therefore, the change in the resistance of the lead wire, such as the thermal resistance body, will affect the temperature measurement.

2) Armored thermal resistance

Armored thermal resistor is a solid body composed of a temperature sensing element (resistor), lead wire, insulating material, and stainless steel bushing. Its outer diameter is generally φ2--φ8mm, and the minimum is φmm. Compared with common thermal resistance, it has the following advantages: 1 small size, no internal air gap, thermal inertia, small measurement lag; 2 good mechanical properties, vibration resistance, impact resistance; 3 can bend, easy to install 4 long service life .

3) Face heat resistance

The end face thermo-resistive temperature sensing element is wound by a specially treated resistance wire and is attached to the face of the thermometer. Compared with general axial thermal resistance, it can more accurately and quickly reflect the actual temperature of the tested end face, and is suitable for measuring the end face temperature of the bearing pad and other components.

4) Flameproof thermal resistance

The flameproof thermal resistance is limited to the junction box by the special structure of the junction box, and the explosion of the explosive gas mixture inside the shell due to sparks or arcs is limited to the explosion in the production site. Flameproof RTDs can be used for temperature measurement in explosion-hazardous areas in the Bla-B3c class.

Switching Diode

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