Fluke 1502A-156 Product Manual - Page 20

Callendar-Van Dusen RTD Conversion, IPTS-68 Conversion

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6 General Operation 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 values from the certificate as follows: Table 4 Setting Coefficients R(273.16), a6, b6, c6, and d 1502A Coefficient R0.01 A B C D A4 b4 Certificate Value R(273.16K) a6 b6 c6 d 0.0 0.0 6.4.4 Callendar-Van Dusen (RTD) Conversion The RTD conversion uses the Callendar-Van Dusen equation: ( ) r t[°C ] =  R0 1+   R0  1+  α t  α t  − − δ δ t 100 t 100  t 100  t 100 − 1    − 1÷ − β t 100 − 1 t 100 ÷3     t ≥0 t

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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. For IEC-751 or DIN-43760
sensors, the coefficients for “
r0
”, “
ALPHA
”, “
bEtA
”, and “
dELtA
” should be
100.0, 0.00385, 1.507, and 0.111 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
Ct
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
6.4.5
IPTS-68 Conversion
The IPTS-68 characterization converts resistance to temperature according to
the International Practical Temperature Scale of 1968. The applicable coeffi-
cients are
R
0
(“
r0
”),
α
(“
ALPHA
”),
δ
(“
dELtA
”), a
4
(“
A4
”), and c
4
(“
C4
”). You can
also select the temperature scale (“
SCALE
”) as IPTS-68 (“
68
”) or ITS-90
20
Manual Rev. 952801
Hart Scientific
6
General Operation
1502A Coefficient
Certificate Value
R0.01
R(273.16K)
A
a6
B
b6
C
c6
D
d
A4
0.0
b4
0.0
Table 4
Setting Coefficients R(273.16), a6, b6, c6, and d
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