Walchem WebMaster ONE Instruction Manual page 169

4-20 mA Input Low Alarm
This error message is caused by the 4-20 mA signal being lower than the user-programmed value
for the low alarm limit.
Possible Causes
The process value being measured by the
transmitter is out of specifications.
The low alarm limit for the process being
measured is set too high.
There is a problem with the transmitter that
needs to be addressed by the manufacturer of
the transmitter.
Conductivity Sensor Error
This error message is caused by the signal from the conductivity sensor being outside of the
normal range (input voltage outside –1.45 VDC to +1.45 VDC or a conductivity reading above the
full scale maximum). Any relay controlled by the sensor will be forced off. .
Possible Causes
The conductivity is extremely high
(over full scale).
Faulty core interface or sensor option
circuit board.
Faulty conductivity sensor wiring.
Faulty conductivity sensor.
Corrective Actions
Determine the reason for the out of spec
condition.
Decrease the low limit in the 4-20 mA
Input Page.
Corrective Actions
Go to the Conductivity Input Page and check
the uncalibrated conductivity reading. Compare
this to a calibrated hand held instrument.
Go to the Conductivity Input Page and
perform a self test. If this passes, then the
problem is with the sensor or its wiring.
If it fails, then disconnect the sensor from the
circuit board and repeat the self test. If it
still fails, replace the circuit board.
Make sure that the sensor cable is connected (if
system conductivity) properly, and there are
no shorts in any extension cables. Also make
sure that the sensor cable is not routed near any
AC voltage wiring. Make sure that the cable is
properly shielded.
Replace sensor.
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