ThermoWorks 9141 HART SCIENTIFIC FIELD DRY-WELL TEMPERATURE CALIBRATORS - Manual (Page 45)

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