8 | Flame monitor settings
D-LX 201/721
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8.3 Selecting the gain characteristic curve
NOTICE
Always disconnect the flame monitor before removing the plug-in cover.
Electronic components may be damaged if settings are adjusted under live conditions.
To select the gain characteristic curve the plug-in cover must be removed (see section
7.4.1 Removing the plug-in cover (housing M5/P2) [}55]).
The switching threshold for the flame intensity can only be set to values between
500
and
8000
(see figure Fig.8.3). The flame intensities for flame ON and flame OFF that
are measured with gain characteristic curve V7' (factory setting) also frequently ex-
ceed 8000. In these cases, the displayed intensity will need to be reduced.
1.
To do so, select a smaller gain characteristic curve so that it is possible to set a
switching threshold between the flame OFF signal and the flame ON signal.
Example
: A flame is monitored with gain characteristic curve V7. The following flame
intensities are determined: Flame ON: 50,000 and flame OFF: 10,000
Fig.8.4: Exemplary depiction of a flame signal with setting V6 and V7. When a gain characteristic curve is
changed to the next smallest gain characteristic curve (in this case from V7 to V6), the flame intensity will al-
ways be reduced by a factor of 4.
There is no suitable switching threshold for flame intensities of this magnitude. Select-
ing the gain characteristic curve V6 therefore reduces the flame signal:
Flame ON: 12,500 and flame OFF: 2500; a suitable switching threshold would be
4000, for example
If the gain characteristic curve is set to V8, even a small flame radiation can cause the
switching threshold (intensity) to be exceeded, thereby triggering a flame ON notifica-
tion.
The gain characteristic curves are selected with the Ampl. rotary switches (see
Fig.8.5). Since different gain characteristic curves can be selected for ranges A and B
(see section 8.1 Range selection [}72]), there are separate rotary switches for the two
ranges. The switches for range B only need to be used if this range is in use.
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