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Siemens Building Technologies
Basic Documentation LMV5...
CC1P7550en
HVAC Products
19 Addendum 4: LMV52... with O2 trim control and O2 module
13.08.2004
19.5 O
2
monitor
The O
2
monitor can be used with or without O
2
trim control. When O
2
trim control is ac-
tivated, the O
2
monitor will automatically become active.
19.5.1 Delayed
O
2
min. value
Due to the long time it takes the flue gases to pass through the boiler’s flueways, the
O
2
value currently acquired is delayed compared to the residual oxygen content occur-
ring the same moment in the combustion chamber. To prevent O
2
min. values from be-
ing compared with “old“ O
2
values, the O
2
min. values used by the O
2
monitor are de-
layed by Tau as acquired during adaption, using a software timing element PT1.
19.5.2 Switch-off
criteria
If
a) the actual O
2
value falls for > 3 seconds below the O
2
min. value delayed via the
PT1 timing element, or
b) the actual O
2
value falls for > 3 seconds below the smallest parameterized O
2
min.
value,
one of the following reactions takes place, depending on the operating mode:
Parameter:
O
2
Ctrl/Guard (O
2-guard
/ O
2-c
ontrol)
Safety shutdown will take place, followed by a repetition if possible, otherwise lockout.
Parameter:
O
2
Ctrl/Guard (conAutoDeac)
O
2
trim control will automatically be deactivated and the system operates along the pa-
rameterized ratio curves. O
2
trim control must be manually reactivated.