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Building Technologies
Basic Documentation LMV27...
CC1P7541en
10 Electronic air-fuel ratio control
17.12.2018
10.4.3
Adjustment of output
When the output increases, the LMV27 moves from the curvepoint of stage 1 (P1) to the
switch-on point of stage 2 (P2on). If the switch-on point is exceeded, the valve for the
second stage is switched on. Then, the LMV27 moves to the curvepoint for stage 2 (P2).
When the output decreases, the LMV27 moves from the curvepoint of stage 2 (P2) to
the switch-off point of stage 2 (P2of). If this point is crossed, the valve for the second
stage is switched off. Then, the LMV27 moves to the curvepoint for stage 1 (P1).
In 3-stage operation, the output between stage 2 and stage 3 is adjusted analogously to
2-stage operation. As static outputs, only
P1
,
P2
and
P3
can be approached.
The switch-on and switch-off points are crossed only when changing between stages.
The traveling speeds are fixed. Depending on the positioning angles to be covered, air
actuator does not reach the operating or switch-on / switch-off points at the same time.
The valves are switched on / off only after both actuators have reached their correct
positions.
When parameterizing the curves, the switch-on points can also be approached in a
stationary manner. In addition, when setting the curve via
P2_d
(P3_d), curvepoint
P2
(P3) can be readjusted without traveling to it. In that case, the LMV27 is at the
respective switch-on point. This procedure is used to reduce the operating time if there
is shortage of air.
V3
V2
V1
Valve
B
ild
22
5e
/1
01
0
Air actuator
10 V (100 %)
(90 %)
2 V (10° / 10 %)
0
Figure 65: Adjustment of output
10.4.4 Entering the operating position
The burner is ignited at ignition position
P0
. When entering operating phase
60
,
the
actuators are driven from ignition position
P0
to the operating point of stage 1 (P1) at the
respective traveling speed.
10.4.5 Operating position
In the operating position, the burner’s output can be adjusted between operating points
P1
and
P2
or
P3
in accordance with the load controller’s presetting, as described in
chapter
Adjustment of output
. Ignition position
P0
is not approached anymore. It can
only be reached via curve adjustment.
