46
6
Commissioning
6.6.1.5 Dynamic Probe Test
The VMS monitors the measured O
2
value for changes during operation. If a fluctuation no
higher than 0.2 O
2
vol.% is detected over a period of 10 minutes, a state of excess air is en-
forced by changing the fuel/air mixture. If there is still no change in the actual O
2
value after 1
minute, the test is repeated with more excess air. If this does not lead to a change in the actual
value, the test is performed a third time with even more excess air. If no change has occurred
in the actual O
2
value at this point, the control unit deactivates itself and displays a warning
on the screen. Thereafter the control unit's output (correction input) corresponds to "Base val-
ue without control”.
NOTICE
The O
2
optimisation fault messages do not affect burner or combustion functions.
6.6.1.6 Probe Blockage
Blockages in the probe can cause the measured value to increase slowly but steadily, in such
a way that the dynamic probe test is not triggered. The main processor monitors whether the
actual O
2
value drops by more than 0.2 vol. % O
2
at least once within 15 minutes. If this is not
the case, then a dynamic test is triggered.
NOTICE
O
2
optimisation fault messages have no effect on the burner's function or that of the combus-
tion system. They only notify that:
- O
2
optimisation was deactivated.
- Note error status and firing rate value.
If desired, it is also possible to have the burner shut down on ’Air shortage’ faults via parameter
897.
Summary of Contents for VMS 4
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