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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
19.12 Setting notes
(Summary of the most important rules for setting O
2
trim control)
19.12.1 Parameter
settings
•
Parameterize all truly air-influencing actuators as air-influencing actuators
If changing the parameter settings, O
2
trim control must be readjusted.
19.12.2 Setting O2 ratio control
•
Set sufficient excess O2
Set the amount of excess air of the ratio curve such that, whatever the
environmental conditions (combustion chamber and fuel pressure, tem-
perature and pressure of the combustion air), the set residual oxygen
content will lie above the O
2
setpoints required by O
2
trim control.
Example:
1
2
3
4
5
6
O
2
(%)
100 %
Load (%)
Curvepoints
O
2
ratio control
O
2
setpoint
O
2
min value
Change of O
2
ratio control
due to ambient conditions
75
5
0d3
1
e/
0
90
3
1
2
3
4
5
•
Parameterized load proportional to the fuel rate
The burner load parameterized at the curvepoints must be proportional to the ac-
tual burner load. To make the setting, determine the burner load with the help of
the fuel counter.
•
Curvepoint 1
The first curvepoint should have an adequate distance below curvepoint
d
. This
means that the curve for reducing the air rate is also defined below point
d
. As a
guide value, point
c
should lie at about half the load of point
d
. Point
d
should
be smaller than or equal to the low-fire load.
If, in the low-fire position, no further air reduction is possible (e.g. because the air
damper has already fully closed), curvepoint 1 must be selected as the low-fire
point. In that case, O2 trim control will only be performed up to curvepoint 2.