DURAG D-LX 200, Manual

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Maintenance
98
D − LX 200, D − LX 720
9.5.3 Harmonic detection
The D − LX 200, D − LX 720 can perform a (

) harmonic detection for safety
purposes. During this process, the Compact Flame Monitor observes the
behaviour of the measured flicker frequency over time. The flicker frequency of
a combustion process fluctuates. The measurement of a constant flicker
frequency over several seconds, on the other hand, indicates an artificial light
source, for example. Harmonic detection guarantees that artificial light sources
cannot be classified as flames by the D
− LX 200, D − LX 720.
When the D − LX 200, D − LX 720 measures a constant frequency over 10 s, it
indicates:

"Flame OFF"

"Freq" LED on the front panel flashes

Flame intensity current output remains constantly at 4 mA / 7.2 mA.
If using the D − LX 200 InformationCentre (Flame Information window):

the bar for the Flame Intensity remains fixed at 20 %.

The "Harmonic Frequ." field is active (green).
The harmonic detection is deactivated when the frequency switching threshold
is set to 0 (zero).