The working principle of thermal resistance

We already know the working principle of thermocouple, now talk about the working principle of thermal resistance

belongs to thermal resistance temperature measurement of the contact temperature measurement, although the effect is same measuring the temperature of the liquid object, but the principle and characteristics of them is different. Thermal resistance is also widely applied in industry, but because of his temperature range makes his application by certain restrictions, thermal resistance temperature measurement principle is based on the conductor or semiconductor resistance changes with the change of temperature characteristics. Its many advantages, can also remote transmission signal, high sensitivity, strong stability, compatibility and accuracy are better, but need the power supply, can not instantaneous measured the change in temperature. Industrial heat resistance generally adopts Pt100, Pt10 Cu50, Cu100, platinum thermal resistance temperature measurement range is generally 200 - below zero 800 ℃, the thermal resistance of copper of 40 to 140 ℃ below zero. Thermal resistance and thermocouple as the distinction between the type, but he does not need compensation conductor, and is much cheaper than thermocouple. The main technical indicators:

temperature measurement range and tolerance

temperature thermal resistance category range ℃

dividing, allowable deviation delta t ℃

WZP

- platinum resistance 200 ~ 600

Pt100

B ( - 200 ~ 600 ℃ tolerance + / - ( 0. 30 + 0. 005 t | |)

grade A ( - 200～550℃) Tolerance + / - ( 0. 15 + 0. 002 t | |)

WZC type copper resistance - 50～100

Cu50

- 50 ~ 100 ℃ tolerance + / - ( 0. 3 + 6. 0×10- 3 t)

note: type in the 't' for thermal components measured temperature of the absolute value.

element thermal resistance temperature 100 ℃ when the resistance value of ( R100中) And it is in 0 ℃ when the resistance ratio (R0 R100中/ R0)

dividing Pt100: grade A R0 = 100 + 0. 06 Ω

B R0 = 100 + 0. 12Ω

R0 / R100中= 1。 3850

dividing Cu50: R0 = 50 + 0. 05年Ω

R0 / R100中= 1。 428±0. 02

heat resistance materials, heat resistance temperature measurement is based on the metal conductor resistance value increases with the increase of the temperature of the properties for temperature measurement. Heat resistance is mostly made of pure metal materials, the application at present most is platinum and copper, in addition, now have begun to use the materials such as nickel, manganese and rhodium manufacturing thermal resistance. Main characteristic

pressure reed temperature sensing element, ant-vibration performance is good. , temperature measurement precision is high; High mechanical strength, good resistance to high temperature and pressure performance; Imported film resistance element, reliable and steady performance. Working principle of the

thermal resistance temperature measurement principle is based on a conductor or semiconductor resistance changes with the change in temperature. Thermal resistance are mostly made of pure metal materials, application at present most is platinum and copper, now have begun to use the materials such as nickel, manganese and rhodium manufacturing thermal resistance. Thermal resistance usually need to get the resistance signal through wire transfer to the computer control device or other secondary instrument.

thermal resistance structure

( 1) Proficient in thermal resistance: industrial commonly used thermal resistance temperature components ( The resistor body) The structure and characteristics. In temperature measurement principle of thermal resistance, measured the change in temperature is directly measured by the change of the thermal resistance tolerance, therefore, the wires of a thermal resistance and so on all kinds of wire resistance change will affect temperature measurement. Three commonly used to eliminate the influence of the lead resistance wire or four wire system.

（ 2) Armored thermal resistance: armored thermal resistance is by thermal components ( The resistor body) , wire, insulation materials, stainless steel casing combination solid body, its diameter is generally from 2 to 8 mm, minimum of phi mm. Compared with the normal thermal resistance, it has the following advantages:

(1) small volume, no internal air gap, thermal inertia, small measuring hysteresis;

2. Good mechanical properties, resistance to vibration and impact resistant;

3. Can bend, easy to install

4. Long service life.

( 3) Transverse thermal resistance: transverse thermal resistance temperature sensing element resistance wire winding by special processing, close to the face in the thermometer. Compared with general axial thermal resistance, it can reflect more correctly and quickly end face of the actual temperature being measured, is suitable for measuring temperature bearing and other parts of the face.

（ 4) Flameproof thermal resistance: flameproof thermal resistance through the special structure of the junction box, its shell internal explosive mixed gas by affected by sparks or electric arc explosion limit within the junction box, that wouldn't make production field explosion. Flameproof thermal resistance can be used in the Bla ~ B3c zone with explosion danger place temperature measurement.