Endress+Hauser CCS120D, Operating Instructions Manual

Page: 26 / 44

Diagnostics and troubleshooting CCS120D
26 Hauser
8 Diagnostics and troubleshooting
When troubleshooting, the entire measuring point must be taken into account. This
comprises:
• Transmitter
• Electrical connections and lines
• Assembly
• Sensor
The possible causes of error in the following table refer primarily to the sensor. Before
commencing troubleshooting, ensure that the following operating conditions have been met:
• The chlorine content is within the measuring range of the sensor (check with the DPD-1/
DPD-3 method)→  35.
• The pH value is within the pH range of the sensor →  37.
• The temperature is within the temperature range of the sensor →  37.
• The conductivity is within the conductivity range of the sensor →  37.
• Measurement in "temperature-compensated" mode (can be configured on transmitter
CM44x) or constant temperature following calibration
• Medium flow rate of at least 30 l/h (7.9 gal/h)(red bar mark when using the CCA250 flow
assembly)
If the value measured by the sensor differs significantly from that of the DPD method,
first consider all possible malfunctions of the photometric DPD method (see Operating
Instructions for photometer). If necessary, repeat the DPD measurement several times.
Error Possible cause Remedy
No display, no sensor current No supply voltage at the transmitter
‣
Establish mains connection
Connection cable between sensor
and transmitter interrupted
‣
Establish cable connection
There is no electrolyte in the
membrane cap
‣
Fill membrane cap with fresh electrolyte
→  29
No input flow of medium
‣
Establish flow, clean filter
Zero point has shifted 1. Check condition of counter electrode.
2. Reset transmitter to factory settings.
Display value too high Polarization of the sensor not yet
completed
‣
Wait for polarization to be completed
Membrane defective
‣
Replace membrane cap
Shunt resistance (e.g. moisture
contact) in the sensor shaft
‣
Remove membrane cap, rub working
electrode dry.
‣
If the transmitter display does not return to
zero, there is a shunt present: replace sensor.
Foreign oxidants interfering with
sensor
‣
Examine medium, check chemicals
DPD chemicals are too old
‣
Replace DPD chemicals.
pH value < pH 5
‣
Stay within permitted pH range (pH
5.5 to 9.5.