Endress+Hauser Liquisys M CLM253 - Page 85

Liquisys M CLM223/253 Diagnostics and troubleshooting
Endress+Hauser 85
Error Possible cause Tests/remedial action Tools, spare parts
Incorrect line resistance
in field A6
Enter correct value CYK71: 165 Ω/km
Implausible
measured values
in general:
• Continuous
measured value
overflow
• Measured value
constantly 000
• Measured value
too low
• Measured value
too high
• Measured value
frozen
• Current output
value not as
expected
Short-circuit/moisture in
sensor
Check sensor See the "Checking
inductive conductivity
sensors" section.
Short-circuit in cable or
socket
Check cable and socket See the "Connecting lines
and junction boxes"
section.
Disconnection in sensor Check sensor See the "Checking
inductive conductivity
sensors" section.
Disconnection in cable or
socket
Check cable and socket See the "Connecting lines
and junction boxes"
section.
Incorrect cell constant
setting
Check cell constant Sensor nameplate or
certificate
Incorrect output
assignment
Check assignment of measured
value to current signal
Incorrect output function Check preset value (0-20 / 4 -20
mA) and curve shape (linear /
table)
Air pockets in assembly Check assembly and installation
position
Grounding short at or in
device
Measure in insulated device Plastic vessel, calibration
solutions
Transmitter module
defective
Check with new module See the "Spare parts"
section
Device in impermissible
operating condition (does
not respond when key
pressed)
Switch off device and switch it on
again
EMC problem: if this
persists, check the
grounding, shields and
line routing or have
checked by E+H Service.
Incorrect
conductivity
measured value in
the process
No/incorrect temperature
compensation
ATC: select type of compensation;
if linear, set suitable coefficients.
MTC: set process temperature.
Incorrect temperature
measurement
Check temperature measured
value.
Reference device,
thermometer
Bubbles in medium Suppress formation of bubbles by:
• Gas bubble trap
• Creating counterpressure
(orifice plate)
• Measurement in bypass
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 SI "Conductivity" or
technical data of
conductivity sensors
Flow rate too high (can
lead to bubble formation)
Reduce flow rate or select less
turbulent mounting location.
Voltage potential in
medium (only for
conductive)
Ground medium close to sensor. Problem mainly occurs in
plastic lines and tanks
Sensor fouling or buildup
on sensor
Clean the sensor (see the
"Cleaning the conductivity sensors"
section).
For heavily contaminated
media:
Use spray cleaning
Incorrect line resistance
in field A6
Enter correct value CYK71: 165 Ω/km