Siemens LMV5 Series Basic Documentation page 254

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18.5 O monitor
2
The O monitor can be used with or without O
2
activated, the O monitor will automatically become active.
2
18.5.1 Delayed O
Due to the long time it takes the flue gases to pass through the boiler's flueways, the
O value currently acquired is delayed compared to the residual oxygen content
2
occurring the same moment in the combustion chamber. To prevent O
from being compared with "old" O
are delayed by Tau as acquired during adaption, using a software timing element PT1.
18.5.2 Switch-off criteria
If
a) the actual O value falls for > 3 seconds below the O
2
PT1 timing element, or
b) the actual O value falls for > 3 seconds below the smallest parameterized O
2
value,
one of the following reactions takes place, depending on the operating mode:
Parameter:
O Ctrl/Guard (O
2
Safety shutdown will take place, followed by a repetition if possible, otherwise lockout.
Parameter:
O Ctrl/Guard (conAutoDeac)
2
O trim control will automatically be deactivated and the system operates along the
2
parameterized ratio curves. O
Basic Documentation LMV51...
18 Addendum 4: LMV52... with O2 trim control and O2 module
trim control. When O
2
min. value
2
values, the O
2 2
/ O
2-guard 2-c
trim control must be manually reactivated.
2
trim control is
2
min. values
2
min. values used by the O
min. value delayed via the
2
ontrol)
monitor
2
min.
2
CC1P7550en
01.10.2003