Fluke HART SCIENTIFIC 1502A - Manual (Page 25)

6.4.5 IPTS-68 Conversion
The IPTS-68 characterization converts resistance to temperature according to
the International Practical Temperature Scale of 1968. The applicable coeffi-
cients are R
0
(“r0”), α (“ALPHA”), δ (“dELtA”), a
4
(“A4”), and c
4
(“C4”).
You can also select the temperature scale (“SCALE”) as IPTS-68 (“68”) or
ITS-90 (“90”). Selecting ITS-90 causes the temperature to be adjusted by a
small amount equal to the difference between the ITS-90 and IPTS-68 tempera-
ture scales.
6.4.5.1 Setting the Characterization Coefficients
Probe characterization coefficients are set within the Probe menu after select-
ing the probe characterization type. Each coefficient appears with its name
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 digits (and the sign). The selected 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 you would like to
cancel any changes you have made, you may do so by pressing the
Ω/Exit but-
ton. 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:
E -04
Increase or decrease the exponent using the p and q buttons. Once the exponent
is correct press Enter to accept it.
6.4.5.2 Testing the Coefficients
The 1502A provides a convenient method for testing the coefficients you have
entered to make sure they have been entered correctly. This is done by calculat-
ing temperature for given resistances and comparing the results with tempera-
tures listed on the probe’s calibration report. This conversion test function is
located at the end of the Probe menu. After setting the coefficients “tESt” ap-
pears briefly followed by the resistance value. You can change the resistance by
using the
L and R buttons to move between digits and the U and D buttons
to change a digit. After setting the resistance press Enter. The 1502A will cal-
culate and display the temperature corresponding to the resistance you entered.
21
6 General Operation
Selecting the Probe Characterization