Fault Finding - Grundfos Conex DIS-D Montage- Und Betriebsanleitung

11. Fault finding

The instrument is maintenance-free, repairs can only
be carried out in the factory.
The following table provides you with short
guidelines for possible faults caused by missing or
faulty cables or faults in the sensor system.
Fault
1. No display after
switching-on.
2. SP (setpoint) LED cannot
be selected.
3. Stop (controller stop) LED
cannot be selected.
4. Code numbers cannot be
selected.
®
Conex DIS-D
Fault
1. Measured-value display
unsteady.
2. Display at full-scale value. a)
3. Alarm during calibration.
4. Sensor value too small
compared to reference.
5. Sensor value too high
compared to reference.
Cause
a) Power supply disconnected.
a) Code 2001 activated.
a) Controller configuration has not
been made.
a) Enable code 0086 has been
deleted; instrument is protected
against unauthorised
operation.
Cause
a) Interferences on lines from
electrode/measuring cell.
b) Connection cables/plugs
between measuring cell and
®
Conex DIS interrupted or
moist.
c) Sensor/electrode faulty.
Connection cable between
electrode/measuring cell and
instrument amplifier
interrupted.
b) Measuring electrode faulty
a) Measuring cell/electrodes
contaminated or blocked by
deposits.
a) Incorrect calibration.
b) pH value for measurement
higher than with calibration
(only with chlorine).
a) Incorrect calibration.
b) pH value for measurement
lower than with calibration (only
with chlorine).
Remedy
Connect the power supply.
Delete code 2001.
Carry out controller configuration.
Enter enable code 0086 again. See
section 9.4 Code overview.
Remedy
Check the screen/cable.
Check the cables, and replace if
necessary.
Replace the sensor/electrode. Check
the potentiostatic control voltage, 100
mV, between terminal M (20) and B/R
(21) with operational/connected
measuring cell. Use a voltmeter.
Check cable, and establish
connection.
Replace the measuring electrode.
Remove the electrodes and clean the
measuring and counter electrodes
(see also installation and operating
instructions of the measuring cells).
Repeat the calibration.
Keep pH value constant for
measurement and calibration.
Repeat the calibration.
Keep the pH value constant for
measurement and calibration.
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