Fluke 9933 - Manual (Page 28)

Note: If CJC readings are entered in temperature, the standard thermo-
couple coefficients for the selected thermocouple type are used to calcu-
late the voltage at each reading. The calculated voltages are then added to
each corresponding UUT reading before calculating characterization co-
efficients for the UUT. If CJC readings are entered in voltage, they are
converted to the correct scale (i.e. mV or µV) and added to each corre-
sponding UUT reading.
The yellow boxes designate the values that must be filled in for the type of co-
efficients being calculated to produce an exact solution. Entering values into
the white boxes is optional and produces an overdetermined solution. Section
3.8, Methods Used for Calculating Coefficients, contains additional
information.
Note: The algorithm used to calculate thermocouple coefficients forces
the EMF at 0°C to 0.0µV. Therefore, using a set-point at or near 0°C when
calculating thermocouple coefficients may cause erroneous results. For
best results, use at least two set-points that are not near 0°C (more than
±5°C).
The Import button reads raw data in from an ASCII text file. The data must be
stored in the text file in the format required for calculating Thermocouple coef-
ficients. The import file format for thermocouple coefficients is discussed in
Section 3.4.3.
The Export button saves the current raw data to an ASCII text file.
The Calculate button calculates the coefficients and displays the Coefficients
and Residuals dialog.
A warning message will appear when calculating thermocouple coefficients if
one of the selected set-points is within 5° of 0°C. Selecting the OK button will
attempt to calculate the coefficients. For best results, use at least two set-points
that are not near 0°C (more than ±5°C).
The Cancel button returns to the Thermocouple Probe Coefficients dialog.
3.4 Import/export file format
The format of the import/export ASCII text file is dependent upon the type of
coefficients to be calculated. The following sections explain the required format
for each type of import/export file.
3.4.1 ITS-90 coefficients
The raw data for calculating ITS-90 coefficients can be imported from an
ASCII text file or exported to an ASCII text file by selecting the Import or Ex-
port button respectively on the Raw Data dialog. The file containing the im-
port/export raw data should be saved with a .TXT extension.
9933 TableWare
User’s Guide
24