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Temperature · Interactive Instrumentation Guide
Pt100 RTD Temperature
Heat and cool the process. Compare temperature, sensor response, and the configured transmitter output.
Custom process schematic · not to scale · blue H connection / orange L connection, where applicable.
Equation and live calculation
R = 100[1 + AT + BT² + C(T − 100)T³]; C = 0 for T ≥ 0 °C
Live substitution appears when the demonstration loads.
PV = process value; LRV/URV = lower/upper range values; I = current in mA. Pressure calculations use kPa internally. Selected units apply to inputs, limits, diagrams, and readouts; changing units converts the same physical values without changing the current. Tank calculations use meters internally; z is positive above the bottom tap. ρ = 1000 × specific gravity in kg/m³; g = 9.80665 m/s². H in tank equations means measured height, not the H port. Entered LRV/URV define the current scaling; calculated empty/full tank DP values are reference checks. Set and Reset Points define switch operation; deadband is their absolute difference. Temperature reference equations use °C internally. Mercury pressure units use conventional NIST conversion factors. Vacuum entries are negative gauge pressure; the absolute-pressure readout remains nonnegative. Models assume ideal instantaneous response. Displayed current is limited to the nominal 4–20 mA range: I_display = clamp(I_ideal, 4, 20), where clamp holds a value at its lower or upper limit. This teaching limit does not reproduce manufacturer-specific saturation or alarm currents.
Where it is used
Platinum RTD measurement in an ideal four-wire system, with no lead resistance or self-heating added.
What the demonstration shows
The Pt100 resistance follows the IEC nominal Callendar–Van Dusen relation. The additional C term applies below zero Celsius.
Common mistake to avoid
Use sensor-specific coefficients for precision calibration; nominal values do not represent every individual sensor.
Model assumptions
Nominal IEC α = 0.00385 Pt100, A = 3.9083×10⁻³, B = −5.775×10⁻⁷, C = −4.183×10⁻¹²; −200 to 850 °C. No lead resistance, self-heating, or sensor tolerance is added.
Technical references
WIKA — Callendar–Van Dusen equationsAnalog Devices — RTD measurementEducational model. Consult the instrument manual for installation, configuration, limits, and approved test procedures. No connection to live plant equipment is made.