Endress+Hauser Topcal S CPC310, Руководство по эксплуатации

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Commissioning
80
7.6.12 Set up 2 - Check
SCS electrode monitoring
The sensor check system monitors the pH and reference electrode for incorrect measurement and
total failure.
SCS detects the following reasons for incorrect measurement:
• Electrode glass breakage
• Fine short circuits in the pH measuring circuit, including moisture or contamination bridges at the
terminal points
• Fouling or clogging of the reference electrode
• Leak current for ISFET sensor
The following three monitoring methods are used:
• Monitoring of the high impedance of the pH electrode (alarm when a minimum impedance is
undershot, approx. 500 k
Ω
).
This function cannot be selected for antimony and ISFET electrode types.
• Monitoring the impedance of the reference electrode (alarm when the set threshold value is
overshot).
This function can only be selected for symmetrically high-impedance measurement.
• Monitoring the leak current for ISFET sensors (early warning E168 with I
LEAK
> 200 nA, error
E008 with I
LEAK
> 400 nA).
a0004337
Fig. 56: SCS alarm
"
Caution!
Do not remove standard electrodes from the process without hold! As SCS is measured against PML,
an alarm occurs due to the missing contact between the internal lead and PML. In the case of digital
sensors, SCS is not measured against PML.