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9
Calibration Procedure
9.1
Single Point Calibration
For a quick calibration to a single point, R
any calculations. If the system is reading high, adjust R
menu higher by small increments until the temperature of the system is correct.
NOTE: This method may cause other temperature settings to be off by a
degree or two.
9.2
Three Point Calibration Procedure
In some instances the user may want to calibrate the controller to improve the
temperature set-point accuracy. Calibration is done by adjusting the controller
probe calibration constants R
measured with a standard thermometer, agrees more closely with the set-point.
The thermometer used must be able to measure the temperature with higher ac-
curacy than the desired accuracy of the system.
1. Choose three set-points to use in the calibration of the R
DELTA parameters.
2. Set the controller to the low set-point. When the calibrator reaches the
set-point and is stable, wait 15 minutes or so and then take a reading from the
thermometer. Sample the set-point resistance by holding down the SET key and
pressing the DOWN key. Write these values down as T
3. Repeat step 2 for the other two set-points recording them as T
R
respectively.
3
4. Using the recorded data, calculate new values for R
parameters using the equations given below:
9.2.1
Compute DELTA:
=
A
=
B
=
C
=
D
=
E
−
T
T
3
2
−
T
T
2
1
⎡
⎤
⎡
⎤
⎡
⎤
⎡
T
T
T
−
−
3
3
2
1
1
⎣ ⎢
⎦ ⎥
⎣ ⎢
⎦ ⎥
⎣ ⎢
⎦ ⎥
⎣ ⎢
100
100
100
⎡
⎤
⎡
⎤
⎡
⎤
⎡
T
T
T
−
−
2
2
1
1
1
⎣ ⎢
⎦ ⎥
⎣ ⎢
⎦ ⎥
⎣ ⎢
⎦ ⎥
⎣ ⎢
100
100
100
−
R
R
3
2
may be adjusted by itself without
0
and ALPHA so that the process temperature, as
0
⎤
T
−
2
100 ⎥
⎦
⎤
T
−
1
100 ⎥
⎦
9 Calibration Procedure
Single Point Calibration
in the calibration
0
, ALPHA, and
0
and R
respectively.
1
1
, R
, T
, and
2
2
3
, ALPHA, and DELTA
0
41
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