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iTEMP TMT71/72 Technical data
Measured error digital value (HART):
√(Measured error digital² + Influence of ambient temperature (digital)² + Influence
of supply voltage (digital)²
Measured error analog value (current output):
√(Measured error digital² + Measured error D/A² + Influence of ambient
temperature (digital)² + Influence of ambient temperature (D/A)² + Influence of
supply voltage (digital)² + Influence of supply voltage (D/A)²
0.10 °C (0.18 °F)
0.13 °C (0.23 °F)
The measured error data correspond to 2 σ (Gaussian distribution).
MV = Measured value
LRV = Lower range value of relevant sensor
Physical input measuring range of sensors
10 to 400 Ω Cu50, Cu100, polynomial RTD, Pt50, Pt100, Ni100, Ni120
10 to 2 000 Ω Pt200, Pt500, Pt1000
–20 to 100 mV Thermocouples type: A, B, C, D, E, J, K, L, N, R, S, T, U
Sensor adjustment Sensor transmitter matching
RTD sensors are one of the most linear temperature measuring elements. Nevertheless,
the output must be linearized. To significantly improve temperature measurement
accuracy, the device allows the use of two methods:
• Callendar-Van-Dusen coefficients (Pt100 resistance thermometer)
The Callendar-Van-Dusen equation is described as:
R
T
= R
0
[1+AT+BT²+C(T-100)T³]
The coefficients A, B and C are used to match the sensor (platinum) and transmitter in
order to improve the accuracy of the measuring system. The coefficients for a standard
sensor are specified in IEC 751. If no standard sensor is available or if greater accuracy is
required, the coefficients for each sensor can be determined specifically with the aid of
• Linearization for copper/nickel resistance thermometers (RTD)
The polynomial equation for copper/nickel is as follows:
The coefficients A and B are used for the linearization of nickel or copper resistance
thermometers (RTD). The exact values of the coefficients derive from the calibration
data and are specific to each sensor. The sensor-specific coefficients are then sent to the
Sensor transmitter matching using one of the methods explained above significantly
improves the temperature measurement accuracy of the entire system. This is because the
transmitter uses the specific data pertaining to the connected sensor to calculate the
measured temperature, instead of using the standardized sensor curve data.
1-point adjustment (offset)
Shifts the sensor value
Current output adjustment Correction of 4 or 20 mA current output value.
Endress+Hauser V. 1, Rev. 2, 4-10-2018 51
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