2680A/2686A
Users Manual
A-24
Table A-32. FAI Module 4-Wire RTD Specifications
Accuracy, 3
σ
+
°
C
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 0.03
°
C 0.06
°
C 0.16
°
C 0.25
°
C 0.25
°
C 0.62
°
C 1.10
°
C
0
°
C 0.03
°
C 0.06
°
C 0.20
°
C 0.31
°
C 0.31
°
C 0.85
°
C 1.30
°
C
100
°
C 0.03
°
C 0.06
°
C 0.23
°
C 0.34
°
C 0.34
°
C 0.95
°
C 1.40
°
C
300
°
C 0.03
°
C 0.06
°
C 0.30
°
C 0.41
°
C 0.41
°
C 1.18
°
C 1.70
°
C
600
°
C 0.03
°
C 0.06
°
C 0.53
°
C
0.63
°
C 0.63
°
C 1.62
°
C 2.12
°
C
FAI Module Thermocouple per ITS-1990 Measurement Specifications
The following tables provide FAI Module specifications for the thermocouple
measurement function per ITS-1990.
Table A-33. FAI Module Thermocouple General Specifications
Specification Characteristic
Input Impedance
100 M
Ω
minimum in parallel with 300 pF
Open Thermocouple Detect
Operates by injecting a small ac signal into the input after
each measurement. A thermocouple resistance greater than
1 k
Ω
to 10 k
Ω
is detected as an open input.
Temperature Coefficient
To calculate Thermocouple 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 0.6 and the
specification at 60
°
C is 1.1, then the specification at 40
°
C is
=(1.1-0.6)x(40-28)/(60-28)+0.6=0.7875.
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.
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