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Building Technologies Division
Basic documentation LMV36...
CC1P7544en
Infrastructure & Citiies Sector
11 Electronic fuel-air ratio control
25.09.2013
11.3 Modulating
operation
In modulating mode, it is possible to operate 2 actuators and 1 VSD. The burner‘s
output can be regulated between 20.0% (low-fire) and 100.0% (high-fire) in increments
of 0.1%. Since the actuators are never allowed to operate simultaneously, the output is
increased in small steps of 1%. In the case of an operating ramp of 20% after 100% in
32 seconds, this represents 1 step in 400 ms. Within such an output step, the air
actuator is operated in the first 200 ms, and the VSD and fuel actuator in the second
200 ms.
11.3.1 Definition of curves
The fuel-air ratio curves are defined by 10 curvepoints that are firmly distributed across
the output range. The following assignment applies:
Curvepoint Output Meaning
P0
10%
Point of ignition, not approached in the operating position
P1 20%
Low-fire
P2 30%
P3 40%
P4 50%
P5 60%
P6 70%
P7 80%
P8 90%
P9 100%
High-fire
The actuator positions can be set with a resolution of 0.1°.
Between the curvepoints, the positions are interpolated in a linear manner.
Fuel
Air
VSD
100
90
80
70
60
50
40
30
20
10
0
P
0
1
0
%
Ign
iti
on
po
in
t
P1
20
%
L
o
w
-fi
re
P2
3
0
%
P3
4
0
%
P4
5
0
%
P5
6
0
%
P6
7
0
%
P7
8
0
%
P8
9
0
%
P9
1
0
0 %
Hi
g
h-fi
re
B
ild
385e/
1109
Figure 74: Definition of curves
No. Parameter
401
Ratio control curves fuel actuator (curve setting only)
402
Ratio control curves air actuator (curve setting only)
403
Ratio control curves VSD (curve setting only)
404
Fuel 1: Ratio control curves fuel actuator (curve setting only)
405
Fuel 1: Ratio control curves air actuator (curve setting only)
406
Fuel 1: Ratio control curves VSD (curve setting only)