2 compute r0 & alpha: 44, Compute r, Alpha – ThermoWorks 9141 HART SCIENTIFIC FIELD DRY-WELL TEMPERATURE CALIBRATORS User Manual
Page 45: 2 compute r
C
T
T
T
T
= ⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦⎥
− ⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦
3
3
2
2
100
1
100
100
1
100 ⎥
D
T
T
T
T
= ⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦⎥
− ⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦
2
2
1
1
100
1
100
100
1
100 ⎥
E
R
R
=
−
3
2
F
R
R
=
−
2
1
delta
AF
BE
DE
CF
=
−
−
T
1-3
- Measured temperature using thermometer.
R
1-3
- Value of R from display of 9141 (Press SET and DOWN at the same
time.)
where
T
1
and R
1
are the measured temperature and resistance at 50.0 °C
T
2
and R
2
are the measured temperature and resistance at 250.0 °C
T
3
and R
3
are the measured temperature and resistance at 450.0 °C
10.2.2
Compute R
0
& ALPHA:
a
T
delta
T
T
1
1
1
1
100
1
100
=
+
⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦⎥
a
T
delta
T
T
3
3
3
3
100
1
100
=
+
⎡
⎣⎢
⎤
⎦⎥
−
⎡
⎣⎢
⎤
⎦⎥
rzero
R a
R a
a
a
=
−
−
3
1
1
3
1
3
alpha
R
R
R a
R a
=
−
−
1
3
3
1
1
3
delta is the new value of DELTA computed above
5. Program the new values for DELTA (delta), R
0
(rzero) and ALPHA (alpha)
into the dry-well with the following steps.
a. Press SET and EXIT keys at the same time and then press SET until R
0
is displayed.
9141 Dry-well Calibrator
User’s Guide
44