Fluke 7341 - Calibration Example

7341
Users Guide
11-4
t
H
and measuring the errors again. If desired, the calibration procedure may be repeated
again to further improve the accuracy.
Calibration Example
The bath is to be used between 25°C and 75°C and it is desired to calibrate the bath as
accurately as possible for operation within this range. The current values for R0 and
ALPHA are 100.000 and 0.0038500 respectively. The calibration points are chosen to be
30.00 and 80.00°C. The measured bath temperatures are 29.843 and 79.914°C
respectively. Refer to Figure 11-1 for applying equations to the example data and
computing the new probe constants.
R0 = 100.000
ALPHA = 0.0038500
t
L
= 30.00°C
measured t = 29.843°C
t
H
= 80.00°C
measured t = 79.914°C
Compute errors,
err
L
= 29.843 - 30.00°C = -0.157°C
err
H
= 79.914 - 80.00°C = -0.086°C
Compute R0′,
R
0
0 086 30 0 0157 80 0
80 0 30 0
0 00385 1′=
−×−−×
−
+
⎡
(. ) . (. ) .
..
.
⎣
⎢
⎤
⎦
⎥
=100 000 100 077..
Compute ALPHA′,
ALPHA′=
+×−−+×−(. .)(.)(. .)(1 0 00385 80 0 0157 1 0 00385 30 0
0 086
80 0 30 0
1 0 00385 0 0038416
.)
..
..
−
+
⎡
⎣
⎢
⎤
⎦
⎥
=
haz008.eps
Figure 11-1. Calibration Example