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Building Technologies
Basic Documentation LMV5...
CC1P7550en
19 O2 trim control with LMV52 and PLL52
22.05.2018
19.6.2 Checking the O2 content (20.9%)
Every time the burner is started up, the measured residual O2 content is compared with
the O2 content of the ambient air at the end of prepurging.
This test detects offset errors of the measuring cell.
Normally, this value reads 20.9%, but it can be parameterized in the case of plants that
operate with enriched air.
Parameter
Gas:
O2 Content Air
Oil:
O2 Content Air
For the QGO20, the tolerance band for checking the O2 content is =
±2%.
If the O
2
content lies outside the tolerance band of ±2%, one of the following reactions
takes place, depending on the parameterization of
O2Contr/Alarm.
man deact
(auto deact):
O2 trim controller and O2 alarm are deactivated. No O2 test is made
O2 Alarm / O2
Control:
O2 trim controller / O2 alarm is / are activated. If the test is negative,
safety shutdown is initiated, followed by a repetition if possible,
otherwise lockout
conAutoDeac
:
O2 trim controller and O2 alarm are activated.
If the test is negative, both the O2 trim controller and the O2 alarm
are deactivated.
Caution!
For that purpose, the prepurging time of the LMV52 must be parameterized such
that the combustion chamber and the flueways will be completely purged.
The correct setting of the air’s O2 content is safety-related.
