Fault Inspection During Ph Measurement - ECOLAB MULTRONIC Bedienungsanleitung

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Fault inspection during pH measurement

Fault symptom
Display constantly
indicates pH 0 or pH 14
Measuring value
indication unstable
Measuring value
indication jumps by
several digits
Error message
'plausibility error' during
calibration
Error message
'time out error'
during calibration
Indication does not move
to value of buffer solution
during calibration
The indication in the
buffer solution is OK, the
measured value in the
measuring water changes
Indication remains at
approx. pH 7 despite
changed pH value
Indication changes when
medium flows
Indication too slow
417101804_Anhang03_pH.doc
Cause / fault
Connection lead measuring cell –
measuring amplifier disconnected
Air in measuring water
Measuring lead from the
measuring cell defective
Wrong calibration solution
Measuring chain too slow
Strong measured value fluctuations See error description 'strong
Electrode too slow during
calibration
Old measuring chain
Earth fault in the signal output
circuit (0-20 mA)
Short circuit in the electrode lead,
i.e. moisture short circuit in the
plug-in connections
Flow too strong
Long measuring lead
pH Measuring Module
Rectification
Check connecting lead and establish
connection
Measuring water, i.e. extraction
connection to be adjusted in such a
way that no air bubbles can get into
the measuring cell
Check whether the shield is
connected correctly. If required, use
double shielded cable, i.e. impedance
converter
Use correct buffer
See error description 'indication too
slow'
measured value fluctuations'
See error message 'indication too
slow'
Replace measuring chain
Check signal output circuit for earth
fault, use zero-potential measuring
module
Check electrode cable at the
connection area, check plug for
moisture
Measure in bypass, i.e. reduce flow
reduce distance if possible
- 52 - Rev.: 07-07/10