FLUKE 1504-156 User Manual for the Fluke 1504-156 Thermometer Readout, Tweener Thermistor, ±0.002°C at 0°C Temperature Accuracy

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6.4 Selecting the Probe Characterization

Before the 1502A can measure temperature accurately it must know how to

calculate temperature from the resistance of the sensor. You must select a

conversion 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 algo-

rithms use coefficients that characterize the sensor. Coefficients are deter-

mined 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

characterization 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,

+4.336079

For some coefficients, you only need to set the digits in the number. Other co-

efficients 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 se-

lected digit will flash. Use the U and D buttons to change a digit. Once the

sign and digits are correct, press Enter to accept the number. If you decide to

cancel any changes you have made, you may do so by pressing the Ω/Exit

button. This will immediately skip to the next coefficient.

If the coefficient also requires an exponent, it will appear after setting the num

ber as follows:

1502A Manual Rev. 952801 17

6 General Operation

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FLUKE 1504-156 Thermometer Readout, Tweener Thermistor, ±0.002°C at 0°C Temperature Accuracy