User Defined Function Data - 155
Figure 148: Example of configuration page for Callendar van Dusen
constant and coefficients
Callendar van Dusen formula for PRTs can be defined using one of two
equations, each with their own coefficients: A, B and C or alpha, delta
and beta (α, δ and β). Additionally, a constant, R
0
, is needed to define the
sensor.
MC6-T supports the use of the equation using coefficients A, B and C only.
If your PRT's calibration certificate includes coefficients α, δ and β, use the
following equations to convert them to A, B and C:
Figure 149: Equations for converting coefficients.
ITS-90 PRT Sensor
If your calibration certificate includes coefficients for ITS-90 deviation
function (International Temperature Scale of 1990) PRT sensor, select ITS
90 PRT (R tpw,…) as the Sensor Calculation Formula. Then you may
enter the constant, R tpw, and one or more coefficients: a
x
, b
x
…, where
the subscript x is 4 to 11, depending on the deviation formula used in the
calibration.
If the coefficients in your calibration certificate are missing the subscripts,
use the following table to find which coefficients you have been given.
Note: The definition of coefficient notations for the ITS-90
subranges is described in the NIST Technical Note 1265
"Guidelines For Realizing the International Temperature Scale of
1990".
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