Technical / Programming Manual
FT128 Rev 2.2
105
2. After the 7 minutes, the decision value is still over the smouldering level. The pre-
warning level and the fire alarm level are therefore lowered. A 90 minutes timer is
started.
3. The decision value has reached the pre-warning level and pre-warning is activated.
4. After the 90 minutes the decision value is still over the pre-warning level but has
not reached the fire alarm level. The pre-warning level and the fire alarm level are
therefore lowered again. A 120 minutes timer is started.
5. The decision value has reached the fire alarm level and fire alarm is activated.
6. The decision value has reached the original fire alarm level "40" i.e. the fire alarm
would have been activated approx. 90 minutes after the fire alarm is activated by
the smouldering algorithm!
14.4.4 Performance Factor
To find out the environment conditions where an analogue smoke detector 430x and 440x
in NORMAL mode is mounted, the Performance factor (Pf) can be studied. The
performance factor is shown in menu H4/U3 together with the min. and maximum sensor
values. All three values should be studied together e.g. one or two high sensor values will
not result in a high performance factor. The performance factor is calculated for each
detector individually.
Each sensor value is compared with the week average sensor value. The absolute
difference is saved and each twenty-four hour (at midnight) an "average value" is
calculated, i.e. the performance factor. (12343 = samples per 24 hours.)
Where,
X
m
= momentary sensor values for 24 hours.
X
wa
= week average sensor value
If the detector is mounted in a very "stable" environment e.g. an office, the performance
factor will be low (min. 0 %/m).
If the detector is mounted in a very "unstable" environment (like a factory) the performance
factor will be high (maximum 2.55 %/m).
An "unstable" environment can cause nuisance alarms (unnecessary alarms). Perhaps
should another type of detector be used, another alarm algorithm
or other actions be
taken, e.g. alert annunciation or two-unit-dependence (co-incidence alarm).
14.5 Algorithms for Analogue Heat Detectors
The following is valid for the analogue heat detector types 330x in NORMAL mode.
The detector conforms to a class according to the requirements of the tests specified in
AS7240.5.
Each analogue heat detector can have two alarm algorithms programmed (via EBLWin).
One regular alarm algorithm that is normally used (default) and one alternative alarm
algorithm that will be controlled by a time channel (internal or external) e.g. class A1 can
be used during night-time and class B can be used during daytime.
Example: An alternative alarm algorithm during working hours.
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