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Appendix A
System Temperature Error for the DT9871U and DT9874
Table 9
temperature points over the dynamic range of the instrument.
Table 9: Calculated Thermocouple Accuracy of the DT9871U and DT9874
Input
Temp.
–100° C
0° C
100° C
300° C
500° C
700° C
900° C
1100° C
1400° C
a. Conditions for accuracy measurements:
Warm-up time of 45 minutes. Inclusive of typical 0.15
Inclusive of typical 0.25 μV offset error (maximum offset error is 2.5 μV). Exclusive of thermocouple errors.
Exclusive of noise (see
The histograms shown in
distribution for each of the available filter types on the DT9871U and DT9874. Note that
converting μV error to temperature error depends on thermocouple type. For example, a K
thermocouple changes approximately 39 μV per degrees C; therefore, a noise level of 0.1 μV
adds less than 0.003
Figure 32: System Noise on the DT9871U and DT9874 Using No Software Filter (Raw Filter)
108
lists the accuracy of the DT9871U and DT9874 for each thermocouple type at several
J
K
T
±0.17° C
±0.17° C
±0.16° C
±0.15° C
±0.16° C
±0.16° C
±0.18° C
±0.15° C
±0.16° C
±0.15° C
±0.17° C
±0.16° C
±0.15° C
±0.15° C
-----------
±0.15° C
±0.15° C
-----------
±0.15° C
±0.17° C
-----------
±0.15° C
±0.16° C
-----------
-----------
-----------
-----------
Figure 32
and
Figure 33
Figure 32
°
C error (0.1 μV / 39 μV) for a type K thermocouple.
a
Thermocouple Type
E
S
±0.16° C
-----------
±0.15° C
±0.2° C
±0.15° C
±0.18° C
±0.15° C
±0.18° C
±0.15° C
±0.18° C
±0.16° C
±0.18° C
±0.17° C
±0.18° C
±0.19° C
-----------
±0.18° C
-----------
°
C CJC error (maximum CJC error is 0.25
for more information about system noise).
Figure 33
characterize the Gaussian system noise
and
R
B
±0.16° C
-----------
-----------
±0.2° C
±0.16° C
-----------
±0.18° C
±0.15° C
-----------
±0.18° C
±0.23° C
±0.15° C
±0.17° C
±0.21° C
±0.15° C
±0.18° C
±0.17° C
±0.16° C
±0.18° C
±0.19° C
±0.16° C
±0.18° C
±0.18° C
±0.16° C
±0.18° C
±0.17° C
-----------
°
C).
N
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