Sensor-transmitter-matching with the Calendar van Dusen equation
During a calibration, the individual sensor characteristic curve (temperature to resistance) is determined and stored in the transmitter. This ensures the highest accuracy when ordering a thermometer including a temperature transmitter.
VideoMultiple industries03.12.2024
Every Pt100 sensor has an individual temperature to resistance characteristic curve due to small differences in the platinum and manufacturing of the sensor. To achieve an even more accurate measurement than with Class AA Pt100, this individual curve can be exactly linearized, for each individual sensor using the Calendar van Dusen (CvD) equation. This curve must be described as accurately as possible to achieve the highest level of accuracy when linearizing the measured values in the transmitter. For platinum resistors (Pt/RTD), this curve is described using the Calendar van Dusen (CvD) equation.
The accuracy of the complete measuring point, consisting of sensor and transmitter, can be optimized by using the sensor-transmitter-matching technology. The CvD equation looks like this: RT = R0[1+AT+BT²+CT³(T-100 °C)]. The coefficients A, B and C for a certain temperature range can be derived from a calibration with at least 3 points.
If the sensor-specific constants from the thermometer calibration are entered into the transmitter instead of the standardized coefficients from IEC 60751, the transmitter linearizes the specific temperature resistance curve for the connected sensor.
Benefits
Highest degree of accuracy over a large measuring range
Example WITHOUT sensor-transmitter-matching: Pt100 class AA with high accuracy transmitter at 150 °C (302 °F) ±0.4 °C ( ±0.72°F)
Example WITH sensor-transmitter matching: Pt100 matched with high accuracy transmitter at 150 °C (302 °F) ±0.18 °C (±0.324°F)
Economic alternative to paired sensors, particularly at temperatures over 100 °C (212 °F)
Discover our products with sensor-transmitter-matching:
At the end of the course you will know about the features of the PROFINET technology and the PA profiles, network design of 100BaseTX and Ethernet-APL.
