Fluke 6102, Руководство пользователя

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Calibration Procedure
Calibration Points
12 Calibration Procedure
Note: This procedure is to be considered a general guideline. Each laboratory
should write their own procedure based on their equipment and their quality
program. Each procedure should be accompanied by an uncertainty analysis
also based on the laboratory’s equipment and environment.
Sometimes the user may want to calibrate the bath to improve the temperature
set-point accuracy. Calibration is done by adjusting the controller probe calibra tion
constants R0, ALPHA, and DELTA so that the temperature of the bath as measured
with a standard thermometer agrees more closely with the set-point. The thermometer
used must be able to measure the well temperature with higher accuracy than the
desired accuracy of the bath. By using a good thermometer and following this
procedure the bath can be calibrated to an ac curacy of better than 0.5°C up to 200°C.
Calibration Points 12.1
In calibrating the bath, R0, ALPHA, and DELTA are adjusted to mini mize the set-
point error at each of three different bath temperatures. Any three reasonably separated
temperatures may be used for the calibration. Improved results can be obtained for
shorter ranges when using temperatures that are just within the most useful operating
range of the Micro-Bath. The farther apart the calibration temperatures, the larger
will be the calibrated temperature range but the calibration error will also be greater
over the range. If for instance 50°C to 150°C is chosen as the calibration range then
the calibrator may achieve an ac curacy of say ±0.3°C over the range 50 to 150°C.
Choosing a range of 50°C to 90°C may allow the calibrator to have a better accuracy
of maybe ±0.2°C over that range but outside that range the accuracy may be only
±1.5°C.
Calibration Procedure 12.2
Choose three set-points to use in the calibration of the R0, ALPHA, and DELTA 1.
parameters. These set-points are generally 40°C, 95°C, and 195°C but other set-
points may be used if desired or necessary.
Set the bath to the low set-point. When the bath reaches the set-point and the 2.
display is stable, wait 15 minutes or so and then take a reading from the ther-
mometer. Sample the set-point resistance by holding down the “SET” key and
pressing the “DOWN” key. Write these values down as T
1
and R
1
respectively.
Repeat step 2 for the other two set-points recording them as T 3.
2
, R
2
, T
3
, and R
3
respectively.
Using the recorded data, calculate new values for R0, ALPHA, and DELTA 4.
parameters using the equations given below:
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