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Building Technologies Basic documentation LMV37.4... CC1P7546en
10 Electronic ratio control 17.12.2018
10.4 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.
10.4.1 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%.
10.4.2 Traveling speed
The air actuator or the VSD is operated like outside the operating position. 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°.
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