176
The electronic combustion controller utilises the physi-
cal correlation between the level of the ionisation cur-
rent and the air ratio
λ
. The maximum ionisation cur-
rent is achieved at an air ratio of 1 for all gas qualities.
The ionisation signal is evaluated by the combustion
controller and the air ratio is adjusted to a value
between
λ
=1.24 and 1.44. This range provides for an
optimum combustion quality. The gas train regulates
the required amount of gas subject to gas quality.
To check the combustion quality, the CO
2
content or
the O
2
content of the flue gas is measured. The pre-
vailing air ratio is determined using the actual values.
The correlation between CO
2
or O
2
content and air
ratio
λ
is shown in the following table.
Air ratio
λ–
CO
2
/O
2
content
Air ratio
λ
O
2
content (%)
CO
2
content (%)
1.20
3.8
9.6
1.24
4.4
9.2
1.27
4.9
9.0
1.30
5.3
8.7
1.34
5.7
8.5
1.37
6.1
8.3
1.40
6.5
8.1
1.44
6.9
7.8
1.48
7.3
7.6
To achieve optimum combustion control, the system
regularly carries out an automatic self-calibration; also
after power failures (shutdown). For this, the combus-
tion is briefly regulated to maximum ionisation current
(corresponding to air ratio
λ
=1). Self-calibration takes
place shortly after the burner starts and last for about
5 s. During calibration, higher than normal CO emis-
sions may occur briefly.
Function description
Electronic control unit on the peak load boiler
5775 636 GB
Functions
Содержание C3TB
Страница 44: ...44 3 5 1 2x 2 4 7 6 Fig 43 Installation sequence Fitting the front panels 5775 636 GB Installation ...
Страница 48: ...48 14 Fig 47 Installation sequence If required for easier handling Dismantling cont 5775 636 GB Installation ...
Страница 136: ...136 Troubleshooting Repairs gas condensing module cont 5775 636 GB Diagnosis ...
Страница 143: ...143 Parts lists Heat cell assembly 5775 636 GB Components ...
Страница 148: ...148 0001 0001 0003 0003 0002 0002 0004 Fig 118 Parts lists External connection assembly 5775 636 GB Components ...
Страница 154: ...154 0006 0003 0005 0001 0002 0004 Fig 121 Parts lists Miscellaneous assembly 5775 636 GB Components ...
Страница 160: ...160 Parts not shown 0009 PCB IU100 B30 Parts lists Fuel cell assembly 5775 636 GB Components ...
Страница 161: ...161 Parts lists Fuel cell assembly cont 5775 636 GB Components ...
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