Fluke 9933 - Manual (Page 22)

Note: The accepted thermistor model is based upon the logarithmic resis-
tance-temperature characteristic in terms of absolute temperature (Kel-
vin). The accuracy of a model based upon °F or °C has not been tested.
Therefore, TableWare always calculates polynomial coefficients for therm-
istor probes using Kelvin. If Reference readings are entered in °F or °C,
TableWare converts the readings to their Kelvin equivalent values before
the fit is computed.
Valid orders of the polynomial are from 3rd to 6th order. The default for therm-
istor probes is 3rd order. The number of coefficients calculated is one more
than the order of the polynomial (i.e. for a 3rd order polynomial, 4 coefficients
are calculated). The minimum number of set-points needed must exceed the or-
der by 1 or more.
The user is allowed to select whether or not the Steinhart-Hart method is used
when the coefficients are calculated. When Steinhart-Hart is selected, the third
coefficient (squared term) is set to 0.0. Refer to Section 3.7.4, Polynomial Co-
efficients for more information about the Steinhart-Hart method.
The Continue button displays the Raw Data for Polynomial dialog.
The Cancel button returns to the TableWare main display.
3.2.3 Thermocouple probe
The Thermocouple Probe Coefficients dialog (Figure 11) is displayed when the
Continue button is selected from the Probe Information dialog and the coeffi-
cients being calculated are for a thermocouple probe.
Enabled and disabled
All options are enabled at all times.
9933 TableWare
User’s Guide
18
Figure 11 Thermocouple Probe Coefficients dialog