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5. Summary of the SPC-24's functions
5.1. Alarm signal output and indicator lamp
When the beam is obscured by an amount that exceeds the sensitivity setting of the
detector then a fire signal is produced and lighting the fire LED on the receiver.
It should be noted that the SPC-24 has a sophisticated processing and analysing circuit
and therefore a fire will not occur immediately the obscuration exceeds the sensitivity
value, but will take typically 10 to 15 seconds to produce the fire signal. The fire decision
is based on an averaging technique and therefore the time to fire alarm will vary
depending on the level of obscuration and the sensitivity setting.
5.2. Fault signal output and indicator lamp
5.2.1. General
The beam detector may produce a fault condition for one of many different reasons, which
will depend on whether the detector has just been set up or is in normal operation. The
fault signal will be produced and flashing the yellow fault LED on the receiver.
5.2.2. After adjustment/re-initialisation
The beam detector will produce a fault after or during adjustment for one of the following
reasons :-
The receiver cover has been left open for three hours
The cover of the receiver was closed, but the sensitivity was left OFF
The light level is too low reaching the beam
The light level is too high reaching the beam
The sensitivity has been set but the cover of the receiver was not closed within
5 minutes
Synchronization with the emitter is not successful
5.2.3. During normal operation
The beam detector will produce a fault during normal operation for one of the following
reasons :-
The limit of contamination has been reached. The detector is only able to
compensate for contamination or alignment change up to a certain point
The obscuration is greater than 90% (a fire alarm signal will also be
produced(This can be changed by configuration. See Chapter 2.6.2.))
The receiver has come out of synchronization with the emitter.
(Synchronization with the emitter is compensated for at intervals of five
minutes or so. If the emitter alone is turned off and back on, or if the beam is
blocked for more than 30 minutes, compensation will lag behind, resulting in a
fault.)
