Table 3 Matching Certificate Values To The 1529 Its-90 Coefficients - Fluke 1529 Technical Manual

1529 Chub-E4 Thermometer Readout
Probe Menu
6.2.1.1 ITS-90 Conversion
The ITS-90 conversion is for PRTs calibrated and characterized using the Internation-
al Temperature Scale of 1990 equations. The parameters that appear when ITS-90 is
selected are RTPW, A4, B4, A, B, C, and D. These should be set with the correspond-
ing values that appear on the calibration certificate for the PRT. The parameter RTPW
takes the triple point of water resistance from the certificate. The parameters A, B, C,
and D take the an, bn, cn, and d coefficients from the certificate, where n is a number
from 6 to 11. Parameters A4 and B4 take the a4 and b4 coefficients on the certificate.
Any ITS-90 parameter of the 1529 that does not have a corresponding coefficient on
the PRT certificate must be set to 0.
When the ITS-90 conversion type is selected, the RANGE, WIRES, and coefficients
are displayed on the right portion of the bottom of the display. The UD buttons are
used to scroll through the coefficients. Use the Enter button to edit and to save the
new settings. Use the LR buttons to change each digit of the settings. Press and
hold the Exit button to cancel to the main display or press the EXIT button to cancel
and to move to the next parameter. On the last parameter, press the Exit button to exit
the menu.
The RANGE parameter is used to select the appropriate resistance range. For 25 ohm
and 100 ohm PRTs select 100 ohms and for 1000 ohm PRTs select 10K ohms.
The WIRES parameter sets the appropriate number of lead wires from the sensor.
This parameter can be set to 2-, 3-, or 4-wires. See Figure on page for the wiring
configuration.
The following table shows which parameter to set for each of the coefficients that may
appear on the certificate. Note: If the certificate has two sets of coefficients, one set for
"zero-power" calibration and one set for 1 mA calibration, use the coefficients for the
1 mA calibration.)

Table 3 Matching Certificate Values to the 1529 ITS-90 Coefficients

Matching Certificate Values to the 1529 ITS-90 Coefficients
1529 ITS-90 Coefficients
A
B
C
D
A4
B4
The following example demonstrates how to set the ITS-90 parameters for the case
where a PRT was calibrated to ITS-90 and its calibration certificate states values for
coefficients Rtpw, a4, b4, a8, and b8. Set the 1529 parameters with values from the
certificate as follows.
32
Certificate Value
a6, a7, a8, a9, a10, or a11
b6, b7, b8, or b9
c6, c7
d
a4
b4