2645a 2-wire resistance measurement specifications, A-22 – Fluke NetDAQ 2645A User Manual
Page 232
2640A/2645A NetDAQ
Users Manual
A-22
2645A 2-Wire Resistance Measurement Specifications
A-25.
The 2645A specifications for the 2-wire resistance measurement function is based
on the 4-wire resistance measurement specification (above) except you add a 700
to 1000 Ohm positive offset. This value varies for each channel and temperature
gradient (nominal +1%/ºC).
2645A 4-Wire RTD per ITS-1990 Measurement Specifications
A-26.
Tables A-33 and A-34 provide 2645A 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-33. 2645A 4-Wire RTD Temperature Coefficient
Specification
Characteristic
Temperature Coefficient
To calculate RTD accuracy for temperatures
between 28
º
C and 60
º
C, or -10
º
C and 18
º
C,
use a linear interpolation between the two
application points. e.g., if the applicable spec at
28
º
C is .2 and the spec at 60
º
C is .75, then the
specification at 40
º
C is (.75-.2)*(40-28)/(60-28)
+ .2 = .55*(12/32)+.2 = .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-34. 2645A 4-Wire RTD Specifications
Accuracy, 3
σ
±
º
C
Temperature
Resolution
90 Day, 18
º
C to
28
º
C
1 Year,
18
º
C to
28
º
C
1 Year, -10
º
C to
60
º
C
Slow
Fast
Slow
Fast
Slow
Slow
Fast
-200
º
C*
0.03
º
C
0.06
º
C
0.16
º
C
0.25
º
C
0.25
º
C
0.62
º
C
1.10
º
C
0
º
C*
0.03
º
C
0.06
º
C
0.20
º
C
0.31
º
C
0.31
º
C
0.85
º
C
1.30
º
C
100
º
C
0.03
º
C
0.06
º
C
0.23
º
C
0.34
º
C
0.34
º
C
0.95
º
C
1.40
º
C
300
º
C
0.03
º
C
0.06
º
C
0.30
º
C
0.41
º
C
0.41
º
C
1.18
º
C
1.70
º
C
600
º
C
0.03
º
C
0.06
º
C
0.53
º
C
0.63
º
C
0.63
º
C
1.62
º
C
2.12
º
C
* The Custom-385 range is not recommended for use below -80
º
C. See Appendix D.