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3064816_201804
6. Electronic gas/air mixture
Control range
Gas-adaptive combustion air control
Principle:
The relationship between the actual ionisation current and
excess air is used for combustion control.
The system carries out a continuous set/actual comparison
for the ionisation current.
The control unit adjusts the gas throughput via the electronic
gas valve to match the actual ionisation current to the set value.
Set values for the ionisation current for every output value are
stored in the system.
Calibration:
For all gases, the ionisation current is at
its maximum when Lambda
λ
(air ratio) = 1
Þ
The system calibrates automatically
by briefly shifting to Lambda 1.
Þ
Briefly increased CO emissions
When does the system calibrate?
1. Each time the mains supply is switched on.
2. Cyclically after a certain number of burner starts and a
certain burner runtime.
3. After certain faults such as "Flame failure during operation".
CO emissions may be increased during cali
-
bration.
Please
note
Fig.: Ionisation current control diagram
λ
=1,35
λ
=1
Luftzahl [
λ
]
Io
ni
sat
io
ns
st
ro
m
[I
o]
Io
soll
Regelbereich
Io
max
Air ratio [
λ
]
Ionisation
current
[Io]
