digitwill flash. Use the Uand Dbuttons to chang e a digit. Once the sign and
digits are correct, press Enter to accept the number.If you decide to cancel any
changes you havemade, you may do so by pressing the Ω/Exit button. This
will immediately skip to thenext coefficient.
If the coefficientalso requires an exponent, it will appear after setting the num-
ber as follows:
E -04
Increase or decrease the exponentusing the Uand Dbuttons. Once the expo-
nent is correct, press Enter to accept it.
6.4.3 ITS-90 PRT and Coefficients
The ITS-90 option is for PRTscalibrated and characterized using the Interna-
tionalTemperature Scale of 1990 equations. The parameters that appear when
ITS-90 is selectedare “R0.01", ”A", “b”, “C”, “d”, “A4", and ”b4". These
should be setwith the corresponding values that appear on the calibration cer-
tificatefo r the PRT.The parameter “R0.01" takes the triple point of water resis-
tance, oftenlabeled ”Rtpw" or “R(273.16K)” on the certificate. Parameters
“A”,“b”, “C”, and “d” take the an,bn,cn, and d coefficientswhere nis a num-
ber from 5 to 11.Parameters “A4" and ”b4" take the a4 and b4 coefficients or
the a5 and b5 coefficientson the certificate. Any ITS-90 parameter of the
1502A that does not have a correspondingcoefficient on the PRT’s certificate
must be set to 0.
The followingtable shows which parameter to set for each of the coefficients
that may appear on the certificate. The examplesthat follow demonstrate how
to set the ITS-90 parameters for certain cases. (Note: If the certificate has two
sets of coefficients,one set for “zero-power” calibration and one set for 1 mA
calibration, use the coefficientsfor the 1 mA calibration.)
1502A Thermometer Readout
User’s Guide
18
1502AITS-90 Coefficient CertificateValue
A a5,a6, a7, a8, a9, a10, or a11
b b5, b6, b7, b8, or b9
Cc6orc7
dd
A4 a4or a5
b4 b4 or b5
Table 2 Matching Certificate Values to 1502A ITS-90 Coefficients