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Building Technologies
Basic Documentation LMV5...
CC1P7550en
6 Fuel-air ratio control (FARC)
22.05.2018
6.4.5 Approaching low fire in phase 50 / 54
For fuel trains with pilot ignition (Gp1, Gp2, LOgp, HOgp), the following parameter can
be used to specify whether the actuators approach their ratio control positions in phase
54 or beforehand in phase 50.
Parameter
DriveLowfire Gas (LowfireP50 / LowfireP54)
DriveLowfire Oil (LowfireP50 / LowfireP54)
The actuators which, for ignition, have assumed a special position, travel at individually
calculated speeds to ensure that all will reach their low-fire positions at the same time.
25 %
50 %
75 %
90°
P
os
iti
on
Load
Figure 38: Traveling to the low-fire position after ignition
Ι
Note!
The system also allows ignition positions outside the defined range of fuel-air ratio
control, that is, not between nominal load and low-fire.
In the operating position, the dampers are adjusted according to demand. The ratio
control curves are defined for gas and oil.
For modulating operation, the output can be adjusted in increments of 0.1°.
The actuators are driven to the defined ratio control curves.
In multistage operation, 2 or 3 load points can be approached.
For more detailed information, refer to chapter
Operating position.
After there is no more request for heat from the controller, the fuel-air ratio control
system first changes to low-fire (phase 62) before the fuel valves close. For that
purpose, a maximum time is available which can be parameterized
↑
low-fire
shutdown.
Operation
End of operating
position
