Appendices
Specifications
A
A-13
PAI Module 4-Wire RTD per ITS-1990 Measurement Specifications
The following tables provide PAI Module specifications for the 4-wire Resistance-
Temperature Detector (RTD) measurement function. The 4-wire measurements
use 2 input channels a decade apart, e.g., channels 4 and 14.
Table A-16. PAI Module 4-Wire RTD Temperature Coefficient
Specification Characteristic
Temperature Coefficient
To calculate RTD accuracy for temperatures between 28
°
C
and 60
°
C, or -10
°
C and 18
°
C, use a linear interpolation
between the two applicable points. For example, if the
applicable specification at 28
°
C is 0.2 and the specification at
60
°
C is 0.75, then the specification at 40
°
C is =(.75-.2)x(40-
28)/(60-28)+.2=0.406.
Accuracy at -20
°
C
Multiply the -10
°
C to +60
°
C accuracy specification by 2. After
1 hour warm-up. For accuracy between -10
°
C and -20
°
C,
interpolate linearly.
Table A-17. PAI Module 4-Wire RTD Specifications
Accuracy,
3
σ
Temperature
Resolution 90
Day
18
°
C to 28
°
C
1 Year
18
°
C to 28
°
C
1 Year
-10
°
C to 60
°
C
Slow
Fast
Slow
Fast
Slow
Slow
Fast
-200
°
C 0.003
°
C 0.007
°
C 0.06
°
C 0.16
°
C 0.09
°
C 0.33
°
C 0.63
°
C
0
°
C 0.003
°
C 0.007
°
C 0.09
°
C 0.20
°
C 0.13
°
C 0.53
°
C 0.86
°
C
100
°
C 0.003
°
C 0.007
°
C 0.10
°
C 0.23
°
C 0.16
°
C 0.63
°
C 0.97
°
C
300
°
C 0.003
°
C 0.007
°
C 0.14
°
C 0.30
°
C 0.21
°
C 0.83
°
C 1.20
°
C
600
°
C 0.003
°
C 0.007
°
C 0.19
°
C 0.53
°
C 0.30
°
C 1.20
°
C 1.60
°
C
PAI Module 2-Wire RTD per ITS-1990 Measurement Specifications
The PAI Module specifications for the two-wire Resistance Temperature Detector
(RTD) measurement function is based on the four-wire RTD measurement
specification (above) except you add a nominal 5
Ω
(approximately 13
°
C)
positive offset. This value varies for each channel and temperature gradient
(n1%/ºC). Also note that the resistance of the RTD wiring adds directly to
the error. After 100 million operations of a measurement channel, the offset will
increase at an indeterminate rate.
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