Diagnostics and troubleshooting Liquisys M CLM223/253
76 Endress+Hauser
Incorrect conductivity
measured value in process
No / incorrect temperature
compensation
ATC: select compensation type; linear:
set correct coefficient.
MTC: set process temperature.
Incorrect temperature measurement Check temperature value. Reference instrument, thermometer
Bubbles in medium Suppress bubble formation:
– gas bubble trap
– counterpressure (cover)
– bypass measurement
Polarization effects (only with
conductive sensors)
Use suitable sensor
• Use larger cell constant
• Use graphite instead of stainless steel
(check resistance)
Measuring range tables e.g. in FA
"Conductivity" or technical data of
conductivity sensors
Flow rate too high (may cause
bubbles)
Reduce flow or choose low turbulence
mounting position.
Interference current in medium (only
when conductive)
Ground medium close to sensor. Most frequent cause of currents in
medium: defective submerged motors
Sensor soiled or coated Clean sensor (see chapter "Cleaning
conductivity sensors").
Heavily soiled media: use spray cleaning.
Incorrect line resistance in field A6 Enter correct value. CYK71: 165 /km
Measured value
fluctuates
Measuring cable interferences Connect cable screen according to
connection diagram.
See chapter "Electrical connection".
Signal output line interferences Check line routing, try separate line
routing.
Separate routing of signal output and
measuring input lines
Interference currents in medium Eliminate source of interference or
ground medium close to sensor.
With conductive sensors:
Electromagnetic interferences on
signal lines
Use shielded cables and ground the cable
shield
Controller or timer cannot
be activated
No relay module available Install module LSR1-2 or LSR1-4.
Controller/limit contact
does not work
Controller switched off Activate controller. See fields R2xx.
Controller in "Manual/Off" mode Choose "Auto" or "Manual/On" mode. Keyboard, REL-key
Pickup delay setting too long Disable or shorten pickup delay. See fields R2xx.
"Hold" function active “Automatic Hold” during calibration,
“Hold” input activated;
“Hold” via keyboard active.
See fields S2 to S5.
Controller/limit contact
works continuously
Controller in "Manual/On" mode Set controller to "Manual/Off" or "Auto". Keyboard, REL and AUTO keys
Dropout delay setting too long Shorten dropout delay. See field R2xx.
Control loop interruption Check measured value, current output,
actuators, chemical supply.
No conductivity current
output signal
Line open or short-circuited Disconnect line and measure directly on
instrument.
mA meter 0–20 mA
Output defective See chapter "Instrument specific errors".
Fixed conductivity current
output signal
Current simulation active Switch off simulation. See field O3.
Impermissible operating state of
processor system
Switch instrument off and back on. EMC problem: check installation, screen,
grounding if problem persists / call E+H
Service to test.
Error Possible cause Tests and / or remedial measures Equipment, spare parts, personnel
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