Additional Information - User Defined PRT / RTD Sensors 81
CALLENDAR VAN DUSEN FORMULA FOR PRTS
When CvD RTD (R0, A, B, C), i.e. Callendar van Dusen formula is selected,
one additional configuration page is added. See adjacent picture.
Callendar van Dusen formula for PRTs can be defined using one of two equa-
tions, each with their own coefficients: A, B and C or alpha, delta and beta (,
and ). Additionally, a constant, R
0
, is needed to define the sensor.
MC6 supports the use of the equation using coefficients A, B and C only. If your
PRT's calibration certificate includes coefficients , and , use the following
equations to convert them to A, B and C:
Converting coefficients
,
and
to coefficients A, B and C.
Example of configuration page for
Callendar van Dusen constant and coefficients.
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 con-
stant, 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 miss the subscripts, use the fol-
lowing 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".
To Next Page
Loading...
