Fluke NetDAQ 2640A, Service Manual

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NetDAQ
Service Manual
1-18
2640A Thermocouple per ITS-1990 Measurement Specifications 1-27.
Tables 1-24 to 1-25 provide 2640A specifications for the thermocouple measurement
function per ITS-1990.
Table 1-24. 2640A 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 1k to
10k 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.
Table 1-25. 2640A Thermocouple Specifications
Ac
°
C
Thermocouple Resolution 18
°
C to 28
°
C -10
°
C to 60
°
C
90 Day 1 Year 1 Year
Type Temperature
°
C Slow Slow Fast Slow Fast
J -100 to 80 .03 0.45 0.50 0.80 0.60 0.80
80 to 230 .02 0.35 0.50 0.70 0.60 0.80
230 to 760 .02 0.40 0.50 0.70 0.80 0.90
K -100 to -25 .04 0.55 0.60 0.90 0.70 1.00
-25 to 120 .03 0.40 0.50 0.80 0.60 0.90
120 to 800 .03 0.50 0.65 0.90 1.00 1.20
800 to 1372 .03 0.70 1.00 1.30 1.60 1.90
N -100 to -25 .05 0.65 0.75 1.20 0.80 1.30
-25 to 120 .05 0.55 0.60 1.00 0.70 1.10
120 to 1000 .04 0.45 0.60 0.90 1.00 1.20
1000 to 1300 .03 0.55 0.75 1.00 1.20 1.50
E -100 to -25 .03 0.45 0.50 0.80 0.60 0.80
-25 to 20 .02 0.35 0.40 0.60 0.50 0.70
20 to 600 .02 0.30 0.40 0.60 0.50 0.80
600 to 1000 .02 0.40 0.50 0.70 0.90 1.00
T -100 to 0 .04 0.60 0.65 1.00 0.70 1.10
0 to 150 .03 0.40 0.50 0.80 0.60 0.90
150 to 400 .02 0.30 0.40 0.60 0.60 0.80