Decision Value; Alarm Algorithms For Smoke Detectors / Detection Levels / Offsets; Alarm Algorithm / Alternative Alarm Algorithm; Figure 36 Basic Working Principle For Analogue Smoke Sensor - Panasonic Firetracker FT1020G3 CIE Technical And Programming Manual

Also via the Web-server II 1598 you can get "Sensor Information" for all Analogue detectors
on a COM loop.
Sensor value
Obsc. in % / m
3.1
Fire alarm
offset 3.0 %
1.8
0.1
0

Figure 36 Basic working principle for Analogue smoke sensor

The smoke detector sensor values are presented as obscuration in % per meter (%/m).
(Heat detector values as °C.)
17.3

Decision value

In order to secure real fire alarms and reduce the nuisance alarms, a decision value is
calculated. The decision value is used to decide if it is normal state, pre-warning, fire alarm
or heavy smoke alarm and also in the smouldering smoke algorithm (see page 106). The
decision value is calculated, see chapter "Filtering algorithm", page 104.
17.4 Alarm algorithms for smoke detectors / Detection levels /
Offsets
Each alarm algorithm has three detection levels:
1. Fire Alarm (fire alarm level = the week average sensor value + the fire alarm offset)
2. Pre-Warning will be activated (if selected in EBLWin – Control Unit Properties) at
a lower level (smaller offset) than for fire alarm, i.e. pre-warning will be activated
before the fire alarm from the same alarm point.
3. Heavy Smoke Alarm will be activated at a higher level (bigger offset) than for fire
alarm, i.e. heavy smoke alarm will be activated later than the fire alarm from the
same alarm point.
The pre-warning offset and the heavy smoke alarm level can be set in EBLWin for the
whole system, see chapter "Alarm algorithms", page 153.
The fire alarm offset can be set in EBLWin for the whole system, see chapter "Alarm
algorithms", page 153.
Note: Changing the alarm algorithm will affect the sensitivity and detection time and
should not be done, a special password is required to change the fire alarm parameters.
"Pre-warning", "Fire Alarm" and "Heavy Smoke Alarm" can activate programmable outputs.
See chapter "Control expression", page 86 and FT1020G3 Operation Manual.
17.4.1

Alarm algorithm / Alternative alarm algorithm

In order to secure real fire alarms and reduce nuisance alarms, six different alarm
algorithms are available. See Table 12, page 104. The alarm algorithms are based on:

Normal (N), High (H) or Low (L) sensitivity
Constant
sensitivity
1 2 4
Smoke puff
or disturbance
103
Technical/Programming Manual
Service signal
given
6 8 10
Smoke puff
or disturbance
FT1020G3 Rev 2.2.1
Fire alarm level (C)
Sensor value (A)
Week average
sensor value (B)
Service level (D)
Time
12