Fluke HART SCIENTIFIC 1502A - Manual (Page 21)

when all the digits are correct. If the password is entered correctly the first pa-
rameter in the menu will appear.
6.4 Selecting the Probe Characterization
Before the 1502A can measure temperature accurately it must know how to cal-
culate temperature from the resistance of the sensor. You must select a conver-
sion type and enter the proper characterization coefficients. There are several
temperature conversion algorithms available. The one to use depends on the
type of probe you are using and its calibration. The conversion algorithms use
coefficients that characterize the sensor. Coefficients are determined when the
probe is calibrated. SPRTs and PRTs often use the ITS-90 algorithms and are
provided with ITS-90 characterization coefficients.
6.4.1 Setting the Probe Characterization Type
The probe characterization type and characterization coefficients are set in the
Probe menu. Press the Menu button (“SEt?” appears), then the C/Probe but-
ton. The menu name, “ProbE”, will appear briefly then the characterization
type. The probe characterization types are indicated on the display as follows:
Pr= t90 ITS-90
Pr= rtd Callendar-Van Dusen
Pr= t68 IPTS-68
Select the desired probe characterization type using the U and D buttons and
pressing the Enter button. After the characterization type is selected the char-
acterization coefficients follow. The coefficients that appear depend on the
probe type that was selected.
6.4.2 Setting the Characterization Coefficients
Probe characterization coefficients are set within the Probe menu after select-
ing the probe characterization type. Each coefficient appears with the name of a
coefficient shown briefly followed by its value. For example,
A4
+4.336079
For some coefficients, you only need to set the digits in the number. Other coef-
ficients also have a sign as shown above (positive sign appears as “
+ ”). Use the
L and R buttons to move between the digits (and the sign). The selected
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6 General Operation
Selecting the Probe Characterization