SaM - Definition of RTD Sensors • Resistive Temperatrure Detector Sensors • TCR (Temperature Coefficient of Resitance)

Remeber:

• RTD: Resistive Temperatrure Detector (Sensors)
• TCR: Temperature Coefficient of Resistance:${\alpha }_R=\frac{dR}{dT}\frac{1}{R}$This is the “relative” sensivity of this sensor.
  There is an ulterior distinction to be made:
  • PTC: Positive Temperature Coefficent (${\alpha }_R>0$).
  • NTC: Negative Temperature Coefficent (${\alpha }_R<0$).

We can define the TCR (Temperature Coefficient of Resistance), for RTDs as:$\text{TCR}=\frac{R_{100}-R_0}{100°C\cdot R_0}$Where:

• $R_{100}$ is the resistance the sensor assumes at $100°\text{C}$
• $R_0$ is the resistance the sensor assumes at $0°\text{C}$

• The usual sensitivity of these sensors is: $\alpha \simeq +10^{-3}°{\text{C}}^{-1}$.IMPORTANTE
• We have seen two tyes of RTDs:
  • Thin Films:
    
  • Wirewound:
    
• We have seen a special example, which is the PT100 temperature sensor:IMPORTANTE
  This sensor is made of platinum, it is a standard material very stable, reproducible and resist to oxidation.

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Types of RTD