Pt100
A Pt100 is a platinum resistance temperature detector with a nominal
resistance of 100 Ω at 0 °C. rtd_sensor.pt100 implements the verified IEC
60751 PT-385 platinum characteristic over -200 °C through 850 °C.
Quick use
from rtd_sensor import pt100
resistance_ohms = pt100.celsius_to_resistance(100.0)
temperature_c = pt100.resistance_to_celsius(resistance_ohms)
The module also exposes:
from rtd_sensor import pt100
pt100.R0_OHMS
pt100.MIN_TEMPERATURE_C
pt100.MAX_TEMPERATURE_C
pt100.resistance_sensitivity_ohms_per_celsius(25.0)
pt100.temperature_sensitivity_celsius_per_ohm(25.0)
What model is being used?
The built-in Pt100 uses the IEC 60751 PT-385 resistance-temperature relationship. The same normalized characteristic is used by the built-in Pt500 and Pt1000; their reference resistances scale the absolute resistance values.
Example: convert a real resistance estimate
from rtd_sensor import pt100
measured_resistance_ohms = 109.73
temperature_c = pt100.resistance_to_celsius(measured_resistance_ohms)
The value passed here should already be the best available estimate of the sensing element resistance. A measurement interface or hardware driver remains responsible for acquisition details.
Example: predict a calibration point
from rtd_sensor import pt100
expected_ice_point_resistance = pt100.celsius_to_resistance(0.0)
assert expected_ice_point_resistance == 100.0
A physical probe need not measure exactly 100.0 Ω at 0 °C. If you have a
characterized R0, use an
IEC60751RTDModel rather than
changing the built-in nominal model.
Common mistakes
- Treating the IEC characteristic range as a guarantee that a particular probe, sheath, cable, or transmitter is rated for the same full range.
- Adding lead-wire correction inside the RTD model instead of the acquisition layer.
- Assuming a physical Pt100 is exactly equal to the nominal curve at every point.