Fluke HART SCIENTIFIC 1502A - Manual (Page 24)

Example 3:
A PRT was calibrated to ITS-90 and its calibration certificate states values for
coefficients R(273.16K), a6, b6, c6, and d. Set the 1502A parameters with val-
ues from the certificate as follows:
6.4.4 Callendar-Van Dusen (RTD) Conversion
The RTD conversion uses the Callendar-Van Dusen equation:
[ ] ( )
r t C
R t
t t
t
R t
° =
+ − −
⎛
⎝⎜
⎞
⎠⎟
⎡
⎣⎢ ⎤
⎦⎥ ⎧
⎨
⎩
⎫
⎬
⎭
≥
+
0
0
1
100 100
1 0
1
α δ
α − −
⎛
⎝⎜
⎞
⎠⎟ −
−
⎛
⎝⎜
⎞
⎠⎟
⎛
⎝⎜
⎞
⎠⎟
⎡
⎣
⎢
⎢
⎤
⎦
⎥ δ β
t t t t
100 100
1
100
1
100
3
⎥
⎧
⎨
⎩⎪
⎫
⎬
⎭
<
⎧
⎨
⎪
⎪
⎩
⎪
⎪
t 0
The coefficients R
0
,
α, β , and δ can be set by the user. They are indicated as
“r0”, “ALPHA”, “bEtA”, and “dELtA” on the display. The ALPHA coeffi-
cient is scaled by a factor or 1000 to allow adequate resolution. For IEC-751 or
DIN-43760 sensors, the coefficients for “r0”, “ALPHA”, “bEtA”, and
“dELtA” should be 100.0, 0.00385055, 1.49979, and 0.1086 respectively.
Some probes may be provided with A, B, and C coefficients for the
Callendar-Van Dusen equation in the following form:
[ ]
( )
( )
( )
[ ] r t C
R At B
R At Bt C t t
t
t
° =
+ +
+ + + −
≥
< ⎧
⎨
⎩⎪
0
2
0
2 3
1
1 100
0
0
The A, B, and C coefficients can be converted to
α, δ, and β coefficients using
the following formulas:
α δ β = + = −
+
= −
+
A B
A
B
C
A B
100
100
100
1
10
100
8
1502A Thermometer Readout
User’s Guide
20
1502A Coefficient Certificate Value
R0.01 R(273.16K)
A a6
B b6
C c6
D d
A4 0.0
b4 0.0
Table 5 Setting Coefficients R(273.16), a6, b6, c6, and d