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LSN Peripherals | LSN Smoke | 335
Interference effects from daylight and commercial lighting
sources are filtered out with an optical daylight filter and by
the use of electronic filtering and phase-locked rectification
(ambient light stability: glare test DIN EN 54‑7).
The various light-emitting and photo diodes of the sensor
are individually controlled by the detector electronics.
Consequently, signal combinations are produced that are
independent of each other and ideally suitable for the
detection of smoke, which makes it possible to differentiate
between smoke and interference agents (insects, objects).
In addition, the time characteristics and the correlation of
the optical sensor signals for the fire or interference
detection are evaluated.
Moreover, plausibility checking of the various signals makes
it possible to detect errors in the analysis electronics and
the LEDs.
Chemical sensor (CO gas sensor)
The gas sensor (4) detects mainly the carbon monoxide
(CO) that is produced by a fire, but it also detects hydrogen
(H) and nitrogen monoxide (NO).
The basic measuring principle is CO oxidation on an
electrode and the measurable current that arises from this.
The sensor signal value is proportional to the concentration
of gas.
The gas sensor delivers additional information to effectively
suppress deceptive values.
The CO sensor is monitored by measuring the internal
capacity. If the capacity lies outside the permitted range, an
error message is output on the fire panel. In this case, the
detector continues to operate purely as a scattered light
smoke detector.
Depending on the service life of the gas sensor, the
FAP‑OC 520 Fire Detector switches off the C sensors after
five years of operation. The detector will continue to
function as an O detector. The detector should then be
exchanged immediately in order to be able to keep using
the higher reliability of detection of the OC detector.
Pollution sensor
The contamination level on the detector surface is
continually measured by the pollution sensor (6); the result
is evaluated and indicated in three stages on the fire panel.
Contamination of the detector surface leads to active
adaptation of the threshold (drift compensation) and to a
fault indication in the case of heavy contamination.
Improved LSN features
The 520 Series Fire Detectors offer all the features of the
improved LSN technology:
•
Flexible network structures, including "T-tapping"
without additional elements
•
Up to 254 LSN improved elements per loop or stub line
•
Automatic or manual detector addressing selectable via
rotary switch, in each case with or without auto-
detection
•
Power supply for connected elements via LSN bus up to
300 mA
•
Unscreened fire detection cable can be used
•
Cable length up to 1000 m
•
Downwards compatibility to existing LSN systems and
control panels.
In addition, the FAP‑520 Fire Detectors offer all the
established benefits of LSN technology. The following data
can be read out for each configured detector:
•
Serial number
•
Contamination level of the optical section,
•
Operating hours
•
Current analog values.
In the event of an alarm, individual detector identification
is transmitted to the fire panel.
The sensor is self-monitoring. The following errors are
indicated on the fire panel:
•
Failure of the evaluation electronics or one of the LEDs
on the optical sensor
•
Heavy contamination (instead of false alarm)
•
Failure of the CO sensor (in the case of FAP‑OC 520).
Further performance characteristics
Various operating states are indicated on the detector by
means of a clearly visible two-color LED. In the event of an
alarm, the LED flashes red.
The control of an external detector alarm display is
possible.
Preservation of the LSN loop function is guaranteed in the
event of wire interruption or short circuit by means of
integrated isolators.
The innovative detector locking, which operates on the
ballpoint-pen principle, provides fast and simple insertion
and replacement of the detector. We recommend the
specially developed FAA‑500‑RTL exchanger device,
especially in the case of high installation heights.
To allow convenient detector testing, the FAA‑500‑TTL test
adapter with magnet and additional service accessories is
available. The magnet triggers a reed contact, which sets
the detector in test mode.
Certifications and Approvals
Complies with
•
EN54-7:2000/A1:2002/A2:2006
•
EN54-17:2005
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