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Building Technologies
CC1N7719en
17.07.2018
Function
With this type of flame supervision, the changes in infrared radiation are used to
generate the flame signal. The flame-detecting element is an infrared-sensitive
photoresistor whose spectral sensitivity covers the range of approximately 1...3 µm.
The detector does not respond to constant radiation or radiation with mains frequency
harmonics (e.g. 50 Hz or multiples thereof). The suppression of these radiation
frequencies is made electronically, directly dependent on the current mains frequency
at which the relevant burner control (e.g. LMV5...) is operated. As a result, filtering
takes place within a very narrow band, which means that the signal generated by the
flame can almost completely be utilized since the frequency and the rate of change of
infrared radiation constantly change. Hence, the detector’s ability to capture the flame’s
radiation behind the burner’s baffle plate is extremely high. As a result of the high level
of sensitivity, constant or mains frequency-harmonic extraneous light sources remain
undetected only if the detector itself is not moved. Due to its short-wave spectrum, the
ignition spark will not be detected. The detector’s analog output signal
(0... approx. +5 V) is a measure of the changes of the flame’s radiation intensity.
If the connecting cable length of 180 cm is not sufficient, the burner manufacturer can
extend it up to a maximum of 100 m (also see
Installation notes
).
7719m04/1199
SIEMENS
QRI
Made in Germany
Landis & Staefa
sw
bl
br
max. 1,8 m
Z < 100 m
bl Blue wire = reference line
sw Black wire = signal line
br Brown wire = power line
Z
Extension cable
Maximum detector
cable length
Legend
