Endress+Hauser Liquisys M CLM 223, Operating Instructions Manual

Page: 58 / 83

Problem
Possible cause Remedy Equipment needed, spare parts
Incorrect temperature
value
– Incorrect sensor connection Verify connections using
connection diagram; three-wire
connection mandatory Connection diagram in chpt. 3.4
– Measuring cable defective Check cable for interruption/short/
shunt Ohmmeter; also see chpt. 8.8.2 / .3
– Incorrect sensor type Select sensor type on instrument
(field B1)
Incorrect conductivity
meas. 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
– Polarisation effects (conductive
measuring cells only)
Use suitable measuring cell:
- use larger cell constant,
- use graphite in place of stainless
steel (resistance requirements)
Measuring range tables, e.g. in SI
“Conductivity”, or technical data of
conductivity measuring cells
– Flow rate too high (may cause
bubbles)
Reduce flow or choose
low-turbulence mounting position
– Potential in medium
(conductive only)
Ground medium close to meas. cell Problem mainly occurs in plastic
lines and tanks
– Sensor soiled or coated Clean sensor (s. chpt. 8.8.1) Heavily soiled media: use spray
cleaning
Measured value
fluctuates
– Measuring cable interference Connect cable screen acc. to
connection diagram See chpt. 3.5
– Signal output line interference Check line routing, try separate
line routing Separate routing of signal output
and meas. input lines
– Interference potential in medium Eliminate source of interference or
ground medium close to
conductivity measuring cell
Controller or timer
cannot be activated – No relay module installed Install LSR1-2 or LSR1-4 module See chapters 8.4 and 8.5
Controller / limit contact
does not work
– Controller switched off Activate controller See chpt. 5.5 or 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 “Autom. hold” during calibration,
“hold” input activated;
“hold” via keyboard active See fields S2 to S4
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 fields R2xx
– Control loop interruption Check measured value, current
output or relay contacts, 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 chpt. 8.3
Fixed current output
signal
– Current simulation active Switch off simulation See field O2
– Processor system out of sync Switch instrument off and back on EMC problem: check installation if
problem persists
Incorrect current output
signal
– Incorrect current assignment Check current assignment:
0–20 mA or 4–20 mA? Field O211
– Total load in current loop
excessive (> 500
Ω
)
Disconnect output and measure
directly on instrument mA meter for 0–20 mA DC
Maintenance and troubleshooting Liquisys M CLM 223 / 253
54 Hauser