Endress+Hauser iTHERM TrustSens TM371, Operating Instructions Manual

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Technical Data iTHERM TrustSens TM371, TM372
50 Hauser
Long-term drift
Pt100 sensing element < 1000 ppm/1000 h
1)
A/D converter (digital output - HART®) < 500 ppm/1000 h
1)
D/A converter (analog output - current) < 100 ppm/1000 h
1) This would be detected by the self-calibration
Long-term drift decreases at an exponential rate over time. So it may not be
extrapolated in a linear way for time spans longer than the above given values.
Influence of ambient
temperature
A/D converter (digital output - HART®) at typical
operating conditions < 0.05 K (0.09 °F)
A/D converter (digital output - HART®) at maximum
operating conditions < 0.15 K (0.27 °F)
D/A converter (analog output - current) ≤ 30 ppm/°C (2σ), related to the deviation from the
reference temperature
Typical operating conditions
• Ambient temperature: 0 to +40 °C (+32 to +104 °F)
• Process temperature: 0 to +140 °C (+32 to +284 °F)
• Power supply: 18 to 24 V
DC
Influence of supply voltage According to IEC 61298-2:
A/D converter (digital output - HART®) at typical
operating conditions < 15 ppm/V
1)
D/A converter (analog output - current) < 10 ppm/V
1)
1) Related to the deviation from the reference supply voltage
Sample calculation with Pt100, measuring range +20 to +135 °C (+68 to +275 °F), ambient
tempe25 °C (+77 °F), supply voltage 24 V:
Measured error digital 0.220 °C (0.396 °F)
Measured error D/A = 0.03 % x 150 °C (302 °F) 0.045 °C (0.081 °F)
Measured error digital value (HART): 0.220 °C (0.396 °F)
Measured error analog value (current output): √(Measured error digital² +
Measured error D/A²)
0.225 °C (0.405 °F)
Sample calculation with Pt100, measuring range +20 to +135 °C (+68 to +275 °F), ambient
tempe35 °C (+95 °F), supply voltage 30 V:
Measured error digital 0.220 °C (0.396 °F)
Measured error D/A = 0.03 % x 150 °C (302 °F) 0.045 °C (0.081 °F)
Influence of ambient temperature (digital) 0.050 °C (0.090 °F)
Influence of ambient temperature (D/A) = (35 °C - 25 °C) x (30 ppm/°C x 150 °C) 0.045 °C (0.081 °F)
Influence of supply voltage (digital) = (30 V - 24 V) x 15 ppm/V x 150 °C 0.014 °C (0.025 °F)
Influence of supply voltage (D/A) = (30 V - 24 V) x 10 ppm/V x 150 °C 0.009 °C (0.016 °F)