Siemens LMV51 Series Basic Documentation page 273

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HVAC Products
19.5 O monitor
2
The O monitor can be used with or without O
2
tivated, the O monitor will automatically become active.
2
19.5.1 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 occur-
2
ring the same moment in the combustion chamber. To prevent O
ing compared with "old" O
layed by Tau as acquired during adaption, using a software timing element PT1.
19.5.2 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 pa-
2
rameterized ratio curves. O
Basic Documentation LMV5...
19 Addendum 4: LMV52... with O2 trim control and O2 module
trim control. When O
2
min. value
2
values, the O min. values used by the O
2 2
/ O
2-guard 2-c
trim control must be manually reactivated.
2
trim control is ac-
2
min. values from be-
2
monitor are de-
2
min. value delayed via the
2
ontrol)
min.
2
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CC1P7550en
13.08.2004