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Section 8 Troubleshooting
Error/fault
Possible cause
Remedy
Preventive
measures
Output signal of the sensor is
too low or too high
Incorrect calibration
Repeat calibration
according
Calibrate the sensor more
frequently if required
Sensor output signal is too
low. Sensor cannot be
adjusted to the DPD value.
Settling time too short.
Wait at least 2 hours
Deposit on the tip of the
electrode finger
(measuring electrode)
Clean tip of electrode
finger.
If necessary shorten
maintenance intervals.
Inflow to the measuring
cell is too low
Increase incident flow.
Monitor minimum
incident flow.
Output signal of the sensor
is too low
Sensor cannot be calibrated
to the DPD value
Output signal of the sensor
decreases or stays the
same when the DPD value
is increased
Fluctuating signal
Membrane destroyed:
Electrolyte escaping -
process medium
entering.
Replace membrane cap.
Avoid damaging the
membrane. Do not
knock the sensor
when the membrane cap
is screwed on. Avoid
incident flow containing
coarse particles
Coating on the
membrane cap.
Replace membrane
cap.
Gas bubbles on the
outside of the
membrane.
Increase the flow
briefly.
Check mounting and
change if necessary.
No electrolyte in the
Fill the membrane cap
with electrolyte, See
"Filling membrane cap
with electrolyte"
membrane cap
Sensor output
In addition to the
Avoid adding these
Remove cleaning agents and
Disinfectants completely after
use.
signal is too high.
analyte, the process
substances.
Sensor cannot be
adjusted to the DPD
value.
medium also contains
other oxidizing agents,
for example ClO2, O3
Change the water.
(5) The DPD and
incorrect control
Optimize the control
sensor values match
parameters.
parameters.
and the trend of the
redox measurement is
correct, but the set point
value is not maintained.
The amount of
disinfectant dosed per
unit of time is too high.
Concentration is
exceeded before the
process medium
reaches the sensor.
Reduce the amount
added per unit of time.
Reduce the concentration
of disinfectant in the
solution added.
Sensor and DPD values do
not correspond to each other,
the sensor values fluctuate
System circulation is
too slow. Incorrect
control parameters
Improve mixing.
Optimize control
parameters
Make structural changes to
ensure more thorough
mixing.
