Working principle and characteristics of thermistor

Thermoelectric resistance belongs to the contact temperature measurement in temperature measurement. Although their functions are the same, they measure the temperature of objects and liquids, but their principles and characteristics are not the same. Although thermal resistors are widely used in industry, their application is limited due to their temperature measurement range. The temperature measurement principle of thermal resistors is based on the characteristic that the resistance value of conductors or semiconductors changes with temperature. It also has many advantages, such as remote transmission of electrical signals, high sensitivity, strong stability, good interchangeability and accuracy. However, it requires a power supply and cannot measure temperature changes instantaneously. Industrial thermistors generally use Pt100, Pt10,Cu50,Cu100, The temperature measurement range of platinum resistance thermometers is generally -200-800 ℃, while that of copper resistance thermometers is -40 to 140 ℃. Thermistors and thermocouples have the same type of differentiation, but they do not require compensating wires and are cheaper than thermocouples.

Main technical indicators:
Temperature measurement range and allowable deviation of thermal resistance category Temperature measurement range ℃ division mark allowable deviation △ t ℃ WZP type platinum resistance -200~600 Pt100 Grade B (-200~600 ℃ allowable deviation ± (0.30+0.005 | t |) Grade A (-200~550 ℃) allowable deviation ± (0.15+0.002 | t |) WZC type copper resistance -50~100 Cu50-50~100 ℃ allowable deviation ± (0.3+6.0 × 10-3t) Note: "t" in the formula is the measured temperature * * value of the temperature sensing element. The ratio of the resistance value (R100) of the thermistor temperature sensing element at 100 ℃ to its resistance R0 at 0 ℃: (R100/R0) division number Pt100: Class A R0=100 ± 0.06 Ω
B-class R0=100 ± 0.12 Ω
R0/R100=1.3850
Index number Cu50: R0=50 ± 0.05 Ω
R0/R100=1.428 ± 0.02 Raw materials for production
Thermistor materials are used for temperature measurement based on the characteristic that the resistance value of metal conductors increases with temperature. Most thermistors are made of pure metal materials, with platinum and copper being the most commonly used. In addition, materials such as nickel, manganese, and rhodium have been used to manufacture thermistors.

main features
Pressure spring type temperature sensing element with good anti vibration performance; ·High temperature measurement accuracy; ·High mechanical strength and good high temperature and pressure resistance; ·Imported thin film resistor components with reliable and stable performance.
working principle
The temperature measurement principle of thermal resistance is based on the characteristic that the resistance value of a conductor or semiconductor changes with temperature. Most thermistors are made of pure metal materials, with platinum and copper being the most commonly used. Currently, materials such as nickel, manganese, and rhodium have been used to manufacture thermistors. Thermistors typically require the transmission of resistance signals through leads to computer control devices or other secondary instruments.

Thermistor structure
(1) Proficient Thermistor: The structure and characteristics of temperature sensing elements (resistors) commonly used in industry. According to the temperature measurement principle of thermal resistance, the change in the measured temperature is directly measured by the change in the resistance value of the thermal resistance. Therefore, the change in resistance of various wires such as the lead wires of the thermal resistance body will have an impact on temperature measurement. To eliminate the influence of lead resistance, a three wire or four wire system is generally used.
(2) Armored thermistor: Armored thermistor is a solid body composed of temperature sensing elements (resistors), leads, insulation materials, and stainless steel sleeves. Its outer diameter is generally between 2 and 8mm, and can be as small as 2mm. Compared with ordinary thermistors, it has the following advantages:
① Small size, no air gap inside, low measurement lag in terms of thermal inertia;
② Good mechanical performance, vibration resistance, and impact resistance;
③ Can bend, easy to install
④ Long service life.
(3) End face thermistor: The temperature sensing element of the end face thermistor is wound with specially treated resistance wire and tightly attached to the end face of the thermometer. Compared with general axial resistance thermometers, it can more accurately and quickly reflect the actual temperature of the measured end face, and is suitable for measuring the end face temperature of bearing shells and other components.
(4) Explosion proof Thermistor: Explosion proof Thermistors use a specially designed junction box to confine the explosion of explosive mixed gases inside their casing caused by sparks or arcs within the junction box, and will not cause an explosion on the production site. Explosion proof thermal resistors can be used for temperature measurement in areas with explosive hazards within Bla~B3c class zones.