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Building Technologies Division
Basic documentation LMV36...
CC1P7544en
Infrastructure & Citiies Sector
11 Electronic fuel-air ratio control
25.09.2013
11.4 Multistage
operation
This operating mode is only available when firing on oil. There is a choice of 2-stage and
3-stage operation. Hence, the burner’s output can be modulated via 2 or 3 stages.
Modulation is accomplished by adjustment of the air actuator or the VSD and by
switching the fuel valves for adjusting the amount of fuel.
11.4.1 Definition of curves
Fuel-air ratio control is defined via the 2 or 3 static output points. To switch the valves on
and off, switch-on and switch-off points must be defined.
The following assignments apply:
Curve-
point
Meaning Valve
P0
Point of ignition (not approached in the operating position)
V1
P1 Stage
1
V1
P2on
Switch-on point stage 2. When the angle exceeds this point, the
fuel valve for the second stage is switched on
V1
P2_d
Presetting of point P2 with no approach
V1
P2 Stage
2
V2
P2of
Switch-off point stage 2. When the angle falls below this point, the
fuel valve for the second stage is switched off
V2
P3on
Switch-on point stage 3. When the angle exceeds this point, the
fuel valve for the third stage is switched on
V2
P3_d
Presetting of point P3 with no approach
V2
P3 Stage
3
V3
P3of
Switch-off point stage 3. When the angle falls below this point, the
fuel valve for the third stage is switched off
V3
The actuator positions can be set with a resolution of 0.1°, the speeds with a resolution
of 0.1%.
11.4.2 Traveling speed
The defined ramp speeds are used.
The speed of the VSD can be adjusted separately for speed increase or decrease.
No. Parameter
522 Ramp
up
523 Ramp
down
The setting also acts outside the operating position.
The running speed of the actuators is fixed at 5 seconds for a positioning angle of 90°
for SQM33.4, SQM33.5, and SQN1.
The speed is 10 seconds for a positioning angle of 90° for SQM33.6.
The SQM33.7 requires 17 seconds for a positioning angle of 90°.