Endress+Hauser iTEMP TMT162 Operating Instructions Manual page 54

Technische Daten
Current output adjustment
Operating influences
Influence of ambient temperature and supply voltage on operation for resistance thermometers (RTD) and resistance
transmitters
Designation Standard
Pt100 (1)
Pt200 (2)
IEC
60751:2008
Pt500 (3)
Pt1000 (4)
Pt100 (5) JIS C1604:1984
Pt50 (8)
GOST 6651-94
Pt100 (9)
54
• 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
sensor calibration.
• Linearization for copper/nickel resistance thermometers (RTD)
The polynomial equation for copper/nickel is as follows:
R T = R 0 (1+AT+BT²)
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
transmitter.
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
2-point adjustment (sensor trimming)
Correction (slope and offset) of the measured sensor value at transmitter input
Correction of 4 or 20 mA current output value (not possible in SIL mode)
The measured error data correspond to ±2 s (Gaussian distribution), i.e. 95.45%.
Ambient temperature:
Influence (±) per 1 °C (1.8 °F) change
1)
Digital
Maximum Based on measured value
≤ 0.02 °C 0.002% * (MV - LRV),
(0.036 °F) at least 0.005 °C (0.009 °F)
≤ 0.026 °C
(0.047 °F)
≤ 0.013 °C 0.002% * (MV - LRV),
(0.023 °F) at least 0.009 °C (0.016 °F)
≤ 0.01 °C 0.002% * (MV - LRV),
(0.018 °F) at least 0.004 °C (0.007 °F)
≤ 0.013 °C 0.002% * (MV - LRV),
(0.023 °F) at least 0.005 °C (0.009 °F)
≤ 0.03 °C 0.002% * (MV - LRV),
(0.054 °F) at least 0.01 °C (0.018 °F)
≤ 0.02 °C 0.002% * (MV - LRV),
(0.036 °F) at least 0.005 °C (0.009 °F)
2)
D/A
Maximum
≤ 0.02 °C
(0.036 °F)
≤ 0.026 °C
-
(0.047 °F)
≤ 0.013 °C
(0.023 °F)
≤ 0.008 °C
0.001 %
(0.014 °F)
≤ 0.013 °C
(0.023 °F)
≤ 0.01 °C
(0.018 °F)
≤ 0.02 °C
(0.036 °F)
iTEMP TMT162
Supply voltage:
Influence (±) per V change
Digital
Based on measured value
0.002% * (MV - LRV),
at least 0.005 °C (0.009 °F)
-
0.002% * (MV - LRV),
at least 0.009 °C (0.016 °F)
0.002% * (MV - LRV),
at least 0.004 °C (0.007 °F)
0.002% * (MV - LRV),
at least 0.005 °C (0.009 °F)
0.002% * (MV - LRV),
at least 0.01 °C (0.018 °F)
0.002% * (MV - LRV),
at least 0.005 °C (0.009 °F)
Endress+Hauser
D/A
0.001 %