Siemens LMV50 series

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Building Technologies Basic Documentation LMV5... CC1P7550en
6 Fuel-air ratio control (FARC) 22.05.2018
t
Pos. [°]
Required position
- Value Pos. tolerance
+ Value Pos. tolerance
-2
2
0
< 5 s
7
5
5
0
d
1
5
e
/
1
1
1
5
t
-
Value
Pos. tolerance
+ Value Pos. tolerance
-2
2
0
Alarm
< 5 s
Pos. [°]
Required position
Figure 41: Successful correction <2° Fault < 2° (Stall point at constant output)
The required position is considered to be reached when it is within ° value Tolerancia
pos. (neutral band).
When reaching a new position within ° value Tolerancia pos. (neutral band), the
electronic ratio control makes a fine adjustment on the actuators.
Corrections are only made to the position if the current position deviates from the
required position by more than the value Tolerancia pos. (neutral band). These
corrections are then followed by another fine adjustment.
If, during the load change, an actuator is mechanically blocked, the supply of fuel is
shut down within 3 or 8 seconds.
7550d18e/1115
t
Pos. [°]
< 5 s
- Value Pos. tolerance
+ Value Pos. tolerance
-2
Alarm
Actual
position
Required position
Figure 42: Locking on change of load (approaching <2° / > value position tolerance)
Parameter Pos. tolerance
It may be necessary to adjust the parameter Pos. tolerance in the event of changing
loads (e.g. fluttering damper).
This parameter can be used to set the tolerated deviation between the actual position
and the target position / target speed specified by the electronic fuel / air ratio control
system.
This means that the previous neutral zone of 0.3° (factory setting) can be increased to
1.2°.
The tolerated deviation of the variable speed drive speed is only increased along with it
from 0.6%. This means that the smallest tolerance value is 0.5% and can be increased
to 1.2% (see following table).