Fluke 1502A-156 Product Manual - Page 21

Filtering

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6 General Operation ("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 temperature scales. 6.4.5.1 Setting the Characterization Coefficients Probe characterization coefficients are set within the Probe menu after selecting 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 coefficients 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 button. This will immediately skip to the next coefficient. If the coefficient also requires an exponent, it will appear after setting the number 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 calculating temperature for given resistances and comparing the results with temperatures 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" appears briefly followed by the resistance value. You can change the resistance by using the U and D buttons to move between digits and the L and R buttons to change a digit. After setting the resistance press Enter. The 1502A will calculate and display the temperature corresponding to the resistance you entered. Compare this temperature with the temperatures listed on the probe calibration report to verify that the coefficients you entered are correct. 6.5 Filtering While measuring temperature, the readings may appear to vary. This may be due to actual variations in temperature or electrical noise internal to the 1502A. The filter helps to smooth variations in the measurements and improve resolution. The drawback is that filtering tends to slow the response to changes in temperature. You can increase the filter time constant to further improve accuracy and resolution or decrease the time constant to reduce the re- 1502A Manual Rev. 952801 21 MyFlukeStore Shop for Fluke products online at: www. .com 1.888.610.7664

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(“
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 temperature
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 co-
efficients 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
/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:
E
-04
Increase or decrease the exponent using the p and q buttons. Once the expo-
nent 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 calcu-
lating temperature for given resistances and comparing the results with tem-
peratures 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
appears briefly followed by the resistance value. You can change the resis-
tance by using the
U
and
D
buttons to move between digits and the
L
and
R
buttons to change a digit. After setting the resistance press
Enter
. The
1502A will calculate and display the temperature corresponding to the resis-
tance you entered. Compare this temperature with the temperatures listed on
the probe calibration report to verify that the coefficients you entered are cor-
rect.
6.5
Filtering
While measuring temperature, the readings may appear to vary. This may be
due to actual variations in temperature or electrical noise internal to the
1502A. The filter helps to smooth variations in the measurements and improve
resolution. The drawback is that filtering tends to slow the response to
changes in temperature. You can increase the filter time constant to further im-
prove accuracy and resolution or decrease the time constant to reduce the re-
1502A
Manual Rev. 952801
21
6
General Operation
Shop for Fluke products online at:
1.888.610.7664
www.
MyFlukeStore
.com