LR-Cal LRT F (Pt 100)
Precision reference resistance thermometer probe

The heat treatment performed before shipment of each LR-Cal LRT F (Pt 100) reference sensor involves pre-aging the resistance temperature sensors.

A Pt 100 sensor’s resistance changes not only due to temperature but also due to changes in the microstructure of the platinum (Pt) material used. These effects cause drift:

• Lattice defects and mechanical stresses
  During the sensor’s manufacture, vacancies and stresses develop in the platinum. When the sensor is first put into operation (exposed to temperature), these defects largely heal, causing the resistance to shift.
• Impurities and oxidation
  At higher temperatures, impurity atoms can diffuse into the platinum or react on the surface. These processes are most intense initially, during the first temperature cycles.

Through targeted annealing (near or even above the later maximum operating temperature) and thermal cycling, the processes described above are anticipated. The LR-Cal LRT F (Pt 100) reference sensor is then largely “stabilized” in its microstructure.

What are the benefits for you?

• Lower long-term drift
  This is the main benefit. Pre-aged resistance temperature detectors, such as the LR-Cal LRT F (Pt 100), drift significantly less during operation than a newly manufactured one.
• Better repeatability, lower hysteresis
  The measured values deviate less from one another after such thermal cycles.
• Calibration values remain valid longer
  Class A describes the deviation from the reference value series when the sensor is new. Pre-aging does not improve accuracy; the accuracy used as a reference is established through calibration. This calibration is now based on a stable sensor, meaning you achieve greater stability and, consequently, an even more reliable calibration.