Installation and operating instruction
Combustion manager W-FM 100 und W-FM 200
6 Operation
83054802 1/2018-07 La
105-228
O
2
controller limit (
O2 CtrlThreshold
)
If reliable O
2
trim is not possible in the lower capacity range, (e. g. flue gas velocity
at the O
2
sensor insufficient), the O
2
control limit can be increased in parameter
O2 CtrlThreshold
.
At a burner capacity below the control limit O
2
trim is deactivated. Once the burner
capacity increases again by 5 % points above the control limit, O
2
trim is reactiv-
ated. If the O
2
control limit is below the partial load adaption point, the O
2
control
limit is ineffective.
The flue gas velocity at the O
2
sensor may not be sufficient for reliable regulation
for capacities in the lower load range. Recognisable when the O
2
sensor reacts
very slowly to changes in the O
2
content in the flue gas. In this case increase the
O
2
regulating limit accordingly.
Flue gas velocity [v]:
min: 1 m/s
max: 10 m/s
Formula:
Rule of thumb:
v =
Q
B
L λ
t + 273
273
d
2
0.785 3600
v =
Q
B
0.0046
d
2
t + 273
273
A
A
v
Flue gas velocity [m/s]
Q
B
Fuel throughput [kg/h] [m
3
/h]
L
Stoichiometric air requirement [m
3
/kg] [m
3
/m
3
]
λ
Air number
t
A
Flue gas temperature [°C]
d
Flue gas pipe diameter [m]
Behaviour at load change (
LoadCtrlSuspend
)
Parameter
LoadCtrlSuspend
specifies the threshold at which the O
2
trim locks
out when the load changes. With a change in load
2
the W-FM calculates an ad-
justed burner capacity
3
. If the difference of the reference line exceeds the value
LoadCtrlSuspend
1
O
2
trim is suspended
4
and parameter
O2ModOffset
is activated. If the difference is not maintained, the W-FM releases O
2
trim again
after a delay time (2 x
Tau High-Fire
).
The lower the value set, the more often O
2
trim will be suspended and driven to the
O2ModOffset
set.
2
1
1
3
4
