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A basic example of transferring PRT Calibration Coefficients into a Fluke 8508A


Here are some basic examples of data from typical cal reports and how it corresponds with the adding of the coefficients into the 8508A.  

Example 1

Here is the menu you will see on the 8508A.


Here is the data you will see on the Calibration Report.

Calibration Coefficients from cal report
a4: -4.5216385E-05
b4: 6.3287577E-06
a8 -8.4457421E-05
b8 -8.4233341E-06


 For STD_PRT the first number is the resistance of the probe at the triple point of water (RTPW).

 The second is the a+ value (a8). 

The third is the b+ value (b8). 

The fourth is the c+ value which this cal report doesn't have, so leave this as zero

The fifth is the a- value (a4). 

The sixth is the b- value (b4).

Example 2:

From the cert:


The ITS-90 coefficients A7, B7, and C7 correct for temperatures above the TPW to 660°C which is the ITS-90 subrange 7.  So then you will follow this explanation:


Using the Probe Configuration function In the 8508A, the conversion type should be set to SPRT 1TS90.  The operator will then be asked to input the Rtpw value and the A, B, and C coefficients.



The physical act of getting the coefficients into the 8508A is a front panel menu function and it is well-documented.  However what numbers go where is a bit confusing to customers at times.



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    Chris Book

    The DMM program doesn't make any sense? Why have the DMM input the data out of order compared the certificates?

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