Siemens LMV51.000B2 - Page 65

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Siemens Building Technologies Basic Documentation LMV5... CC1P7550en
HVAC Products 5 Fuel / air ratio control (FARC) 13.08.2004
If, due to external effects, an actuator moves from its required position by more than
± 0.3° (neutral band) for more than 8 seconds, the supply of fuel will be shut down.
t
Pos. [°]
Required
position
-0,3
0,3
-2
2
0 < 5 s
7550d15E/0502
t
-0,3
0,3
-2
2
0
Alarm
< 5 s
Pos. [°]
Required
position
Successful correction < 2° Fault < 2° (Stall point at constant output)
The required position is considered to be reached when it is within ± 0.3°.
When reaching a new position within ± 0.3°, the fuel / air ratio control system makes a
fine adjustment on the actuators.
Readjustments of the position are made only if the current position deviates from the
required position by more than 0.3°, followed by another fine adjustment.
If, during the load change, an actuator is mechanically blocked, the supply of fuel will
be shut down within 3 or 8 seconds.
7550d18E/0502
t
Pos. [°]
< 5 s
-0,3
0,3
-2
Alarm
Actual
position
Required
position
Locking on change of load (approach < 2° > 0.3°)