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11 Calibration in general
Manual entry of calibration values
50
•
You must be logged in as a user with the right to perform calibrations. Fac-
tory-preset users have all of these rights.
⇨
"Passwords and user rights", page 77
•
You must ensure that the calibration default settings for the individual analy-
sis inputs and, possibly, the universal inputs are set correctly. The explana-
tions of the calibration default settings can be found in the chapters on
calibration of the various analysis sensors.
•
In the case of Ci analysis inputs, it should be noted that the optional boards
must undergo a basic calibration during the initial commissioning. If this has
not yet been performed, it is necessary to do so prior to any other calibration.
⇨
Chapter 9.3 "Ci base calibration", page 121
NOTE!
Incorrectly entered calibration values result in incorrect measured values.
Correct measurements are essential for control systems and limit
monitoring.
If calibration values are known, they can also be entered manually. This may be
the case with temperature-compensated conductivity measurements, for in-
stance, when the temperature coefficient of a liquid is known. Another important
application case is the manual entry of relative cell constants of conductivity
sensors. If an ASTM test certificate showing precisely-measured cell constants
is available, in addition to entering the nominal cell constants in the configuration
of the conductivity sensor concerned (cf. Chapter 10.6.6 "CR/Ci analysis inputs
(conductive/inductive conductivity)", page 23), the relative cell constants of all
measuring ranges in the calibration values must be manually entered. The rela-
tive cell constants must be calculated from nominal cell constants (nameplate
for the sensor) and measured cell constants (ASTM test certificate):
(measured cell constant × 100 %) ÷ nominal cell constant = relative cell con-
stant.
Calculation example:
nominal cell constant = 0.1 cm-1
measured cell constant = 0.1014 cm
rel. cell constant =
-1
(0.1014 cm
× 100 %) ÷ 0.1 cm
Known calibration values are entered manually under:
Device menu > Calibration > Select Analog Input > Calibration Values
-1
-1
= 101.4 %
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