ABB Advance Optima Uras 14 - Troubleshooting: Unstable Measurement Value Reading

SHB_U14 Chapter 4: Troubleshooting 4-5
Unstable measurement value reading
Indication
Measurement signal indicating non-reproducible shifts of varying amplitudes.
Status messages
After calibration messages 1, 2, 4, 8 or 16 may appear.
Details
Possible cause Measures
Vibration - Reduce vibration at analyzer site.
- Increase the low pass time constant
(T90).
- Change the chopper wheel
modulation frequency and perform
initial calibration of all IR detectors.
Sample gas path leak Check the sample gas path ahead of
and within the analyzer module for
leaks.
Loss of sensitivity - Check sensitivity change
- Check emitter
- Check IR detector
- Check calibration unit
- Check sample cells
Excessive variation in ambient
temperature
- Follow the instructions in Chapter 2 of
the operator’s manual.
- Configure the module thermostat and
perform initial calibration of all IR
detectors.
Ambient air contains sample
components
- Take measures at the collection site
- Install housing purge
Large variation of sample gas pressure
in sample cell
- Optimize sample gas supply
- Check sample gas outlet and exhaust
lines
Components not secured properly in
beam path
- Check emitter screws and fasteners
- If applicable, check cell mounting O
rings
- If applicable, check calibration cell
slide mechanism
Defective pressure sensor Replace pressure sensor
Defective emitter Replace emitter
Defective IR detector Replace IR detector
Defective IR module circuit board Replace circuit board
Defective Sensor-CPU circuit board Replace circuit board
Defective EEPROM on Sensor-CPU
board
Replace EEPROM and/or reload data
set