Thermocouple temperature sensors are contact temperature measurement devices based on the Seebeck effect, widely used in industry, scientific research, and other fields. Their main characteristics can be summarized as follows:
Core Advantages
Extremely Wide Temperature Range: Common types cover -200℃ to 1300℃, while special types (such as tungsten-rhenium thermocouples) can reach -270℃ to 2800℃.
Simple Structure and Robust Durability: Constructed from two different metal wires welded together with an outer protective sheath, it is vibration-resistant, high-pressure resistant, and suitable for harsh environments.
Fast Response Speed: Low thermal inertia, especially small-diameter or armored types can achieve millisecond-level response.
No External Power Supply Required: It generates its own thermoelectric potential (millivolt-level signal), facilitating long-distance transmission.
Low Cost and Easy Maintenance: Common materials (such as nickel-chromium/nickel-silicon), economical price, and easy replacement.
Diverse Types and Strong Adaptability: Includes armored... Types such as mounting type, end face type, explosion-proof type, and corrosion-resistant type can be selected according to needs.
Main Disadvantages:
Requires cold junction compensation: The output voltage depends on the temperature difference between the hot and cold junctions. Fluctuations in the cold junction temperature will introduce errors, requiring correction via ice bath, compensating wires, or software algorithms.
Low sensitivity: The thermoelectric potential is small (microvolts to millivolts), making it susceptible to electromagnetic interference, requiring high-precision amplification circuits.
Nonlinear output: The thermoelectric potential has a nonlinear relationship with temperature, requiring a calibration table or software linearization.
Limited accuracy: Industrial-grade accuracy is typically... ±0.5%～±1%, lower than platinum resistance thermometers (RTDs).
Material aging after long-term use may affect stability.
Complex calibration: Once drifted, recalibration is difficult and requires specialized equipment.
Typical application scenarios:
Iron and steel metallurgy (furnaces, rolling mills)
Petrochemicals (reactors, boilers)
Power equipment (steam turbines, generators)
Food processing (baking, refrigeration)
Automotive manufacturing (welding, painting)
Lithium battery production (electrode baking)
Selection recommendations (by temperature and atmosphere):
1300～1800℃: Select Type B (Platinum-Rhodium 30-Platinum-Rhodium 6) or Tungsten-Rhenium type
1000～1300℃: Recommended Type S or Type N
<1000℃: Commonly used Type K or Type N
<400℃ or negative temperature: Prioritize Type T or... Type E
Oxidizing/Inert Atmosphere: Suitable for Types S, B, and K; Weak Oxidizing/Reducing Atmosphere: Select Types J and T
Note: Actual selection should also consider factors such as response speed, mechanical strength, anti-interference capability, and cost.
