A-23 – Fluke NetDAQ 2645A User Manual
Page 233
Specifications
2645A Specifications
A
A-23
2645A Thermocouple per ITS-1990 Measurement Specifications A-27.
Tables A-35 to A-36 provide 2645A specifications for the thermocouple
measurement function per ITS-1990.
Table A-35. 2645A Thermocouple General Specifications
Specification
Characteristic
Input Impedance
100 M
Ω
minimum in parallel with 150 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
º
C and 60
º
C, or -10
º
C
and 18
º
C, use a linear interpolation between
the two applicable points. e.g., if the applicable
spec at 28
º
C is .6 and the spec at 60
º
C is 1.1,
then the spec at 40
º
C is (1.1-.6)*(40-28)/(60-
28)+.6 = .5*(12.32) + .6 = .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.
Table A-36. 2645A Thermocouple Specifications
Accuracy
±
º
C
Thermocouple
Resolution
18
º
C to 28
º
C
-10
º
C to 60
º
C
90
Day
1 Year
1 Year
Type
Temperature
º
C
Slow
Slow
Fast
Slow
Fast
J
-100 to 80
.3
0.8
0.9
1.6
0.9
1.7
80 to 230
.2
0.7
0.8
1.4
0.9
1.5
230 to 760
.2
0.7
0.8
1.3
1.0
1.5
K
-100 to -25
.4
1.0
1.1
2.0
1.2
2.1
-25 to 120
.3
0.8
0.9
1.7
1.0
1.8
120 to 1000
.3
0.9
1.1
1.8
1.5
2.2
1000 to 1372
.3
1.2
1.5
2.3
2.0
2.9
N
-100 to -25
.5
1.4
1.5
2.8
1.5
2.9
-25 to 120
.5
1.1
1.3
2.3
1.3
2.4
120 to 1000
.4
1.0
1.1
2.0
1.2
2.1
1000 to 1300
.3
1.0
1.2
1.9
1.6
2.4