Modulating Operation; Definition Of Curves - Siemens LMV37.4 Series Basic Documentation

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10.3 Modulating operation

In modulating mode, it is possible to operate 2 actuators and 1 VSD. The burner's
output can be regulated between 20% (low-fire) and 100% (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.

10.3.1 Definition of curves

The air-fuel ratio curves are defined by 10 curvepoints that are fixed and distributed
across the output range.
The following assignment applies:
Curvepoint Output
P0 10%
P1 20%
P2 30%
P3 40%
P4 50%
P5 60%
P6 70%
P7 80%
P8 90%
P9 100%
The actuator positions can be set with a resolution of 0.1°.
Between the curvepoints, the positions are interpolated in a linear manner.
100
90
80
70
60
50
40
30
20
10
0
Figure 65: Definition of curves
No. Parameter
401 Ratio control curves fuel actuator (only curve setting)
402 Ratio control curves air actuator (only curve setting)
403 Ratio control curves VSD (only curve setting)
Basic documentation LMV37.4...
10 Electronic air-fuel ratio control
Meaning
Point of ignition, not approached in the operating position
Low-fire
high-fire
Fuel
Air
VSD
CC1P7546en
20.09.2013