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Reference Manual
00809-0400-4728, Rev AA
June 2011
Rosemount 644
A-8
Transmitters can be installed in locations where the ambient temperature is between –40 and 85 °C (–40 and 185
°F). In order to maintain excellent accuracy performance, each transmitter is individually characterized over this
ambient temperature range at the factory.
Temperature Effects Examples
When using a Pt 100 ( = 0.00385) sensor input at 30 °C span at 30 °C ambient temperature:
• Digital Temperature Effects: 0.003 °C x (30 - 20) = 0.03 °C
• D/A Effects: No D/A effects apply
• Worst Case Error: Digital + Digital Temperature Effects = 0.15 °C + 0.03 °C = 0.18 °C
• Total Probable Error:
Other Input Types
Millivolt Input -10 to 100 mV 0.0005 mV Entire Sensor Input Range 0.001% of span
2-, 3-, 4-wire Ohm 0 to 2000 0.0084 Entire Sensor Input Range 0.001% of span
(1) Change in ambient is with reference to the calibration temperature of the transmitter 68 °F (20 °C) from factory.
(2) Does not apply to F
OUNDATION fieldbus.
Table A-2. Ambient Temperature Effect
Sensor Options Sensor Reference
Input Range
(°C)
Temperature Effects per 1.0 °C
(1.8 °F) Change in Ambient
Temperature
(1)
Range D/A Effect
(2)
0.15
2
0.03
2
+ 0.153C=