Emerson 644 Weather Radio User Manual


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Reference Manual
00809-0400-4728, Rev AA
June 2011
Rosemount 644
2-10
Lead wire imbalance seen by the transmitter = 0.5
• Pt100 2-wire RTD:
Lead wire resistance seen by the transmitter = 150 m × 2 wires ×
0.025
/m = 7.5
Basic error
0.5
0.00385 / C100 
--------------------------------------------------------------------------------- - 1.3 C==
Error due to amb. temp. var. of 25 °C
0.0039 / C25 C 0.5 
0.00385 / C100
-------------------------------------------------------------------------------------------------------
0.1266C==
Basic Error
Lead Wire Resistance
Pt
R
o

----------------------------------------------------------
=
Error due to amb. temp. variation
Cu
T
amb
 Lead Wire Resistance
Pt
R
o

-----------------------------------------------------------------------------------------------------------------=
Basic error
7.5
0.00385 / C100 
--------------------------------------------------------------------------------- -
19.5 C==
Error due to amb. temp. var. of 25 °C
0.0039 / C25 C 7.5 
0.00385 / C100
-------------------------------------------------------------------------------------------------------
1.9 C==
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