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15.1.4.2
Calibrating the slope
Calibrating the controller diaLog DACb
CAUTION!
Correct sensor operation / Run-in period
Damage to the product or its surroundings
–
Correct measuring and metering is only pos‐
sible if the sensor is working perfectly
–
Please read the operating manual for the
sensor
–
Please also read the operating manuals for the
fittings and other components used
–
It is imperative that the run in periods of the
sensors are adhered to
–
The run in periods should be allowed for when
planning commissioning
–
It may take an entire working day to run in the
sensor
Measuring and control behaviour of the controller
during calibration
During calibration the actuating outputs are deacti‐
vated. Exception: a basic load or a manual control
variable has been set. This remains active. The
measured value output [standard signal output mA]
is frozen, corresponding to its settings in the mA
output menu.
When calibration/testing has been completed suc‐
cessfully, all of the error checks relating to the
measured value are restarted. The controller saves
all the determined data for zero point and slope
upon a successful calibration.
The measured value frozen at the start of calibration is suggested
as a reference value. The reference value can be set using the
arrow keys. Calibration is only possible if the reference value is ≥ 2
% of the measuring range of the sensor.
NOTICE!
Prerequisites for correct calibration of the sensor
slope
–
The reference method needed is used,
depending on the feed chemical used (e.g.
DPD 1 for free chlorine).
–
The run-in period for the sensor has been com‐
plied with; refer to the operating instructions for
the sensor.
–
There is permitted and constant flow at the in-
line probe housing
–
There is temperature balance between the
sensor and the sample water
–
There is a constant pH value in the permitted
range
Material required for calibration of amperometric sensors:
A reference method suitable for the measured variable in ques‐
n
tion
95
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