Panasonic MEW01 351 Planning Manual page 95

Panasonic Electric Works Nordic AB
MEW01351 Rev: - Planning Instructions Fire alarm system EBL512 G3, V1.1.x
Figure 19. An example of the filtering algorithm for an Analog
smoke detector with the step value X = 5. The polling time (t) in
this example is approx. 2.56 seconds.
Explanations to the figure:
In this example, the week average sensor value is "10" at the "starting
point", i.e. due to contamination the pre-warning level has been
adjusted to "32" (10+22) and the fire alarm level to "40" (10+30). The
sensor value is accordingly "10".
In this example, alarm algorithm "N-15" is selected, i.e. normal
detection time 15 sec. and normal sensitivity 3% (30). X = 5. The
detector polling time t ≈ 2.56 sec. (In system EBL512 G3 the
detector polling time t ≈ 6 seconds and the step value "X" is according
to Figure 18 – but the principle is the same.)
At start the sensor values and decision values are approx. equal ("10").
When smoke comes into the detector the sensor values are increasing
and by the fourth polling approx. "27". Since 27-10 > X=5, the
decision value ("10") is increased by X=5 to "15". Next polling the
sensor value is approx. "45", i.e. the decision value ("15") is increased
by X=5 to "20", and so on. In this example the decision value never
comes up to the fire alarm level. When the sensor value is reduced to
approx. "25" the decision value is set to "30", because 35-25=10 >
X=5, i.e. the decision value ("35") is reduced by X=5 to "30", and so
on.
The sensor value has here reached the pre-warning level but
1.
nothing will happen since the decision value has not reached the
pre-warning level.
2. The sensor value has here reached the fire alarm level but nothing
will happen since the decision value has not reached the fire alarm
level.
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