Filtering Algorithm - Panasonic EBL128 Planning Instructions

Panasonic Electric Works Nordic AB
MEW01090 Rev: 3
13.1.6
Analog Normal detection time (15sec.)
detector
Normal detection time (15 sec.) If it was possible to completely fill
up a detector with smoke within 1 sec. there will nevertheless be 15
seconds alarm delay. This alarm delay is a "filter" to reduce nuisance
alarms.
Slow detection time (35 sec.). If it was possible to completely fill up
a detector with smoke within 1 sec. there will nevertheless be 35
seconds alarm delay. This alarm delay is an "extra filter" to reduce
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the nuisance alarms but might not fulfil the EN54-7 specifications.
Alternative alarm algorithm
Each analog smoke detector can have two alarm algorithms
programmed (via Win128). One alarm algorithm that is normally
used (N-15 is default) and one alternative alarm algorithm turned on
/ off by a time channel (internal or external). Normal sensitivity can
for example be used during the night-time and low sensitivity and/or
slow detection time can be used during the daytime, i.e. the alternative
alarm algorithm can be used to reduce nuisance alarms
working hours. The actual (current) alarm algorithm is shown in
menu H4/U3.
The alarm algorithm parameters can, for all detectors, be set in
Win128, see chapter "Alarm Algorithms", page 121. See also Win128
help.

Filtering algorithm

In order to secure a fast detection of real fire alarms and to reduce
nuisance alarms to a minimum, the filtering algorithm is used in the
six different alarm algorithms.
The filtering algorithm uses the sensor value to calculate a decision
value depending on which alarm algorithm that is selected.
The decision value starts at zero. Each time a new sensor value is
picked up (sampled) from an analog smoke detector, this new sensor
value is compared with the actual decision value, which will be
adjusted, see below.
If the difference, between the new sensor value and the actual decision
value is < "X", the decision value is set equal to the new sensor value.
If the difference, between the new sensor value and the actual decision
value is > "X", the decision value is increased (or decreased) by "X".
The decision value will consequently not be increased / decreased
with a value exceeding the "X" value even if the sensor value is much
higher / lower, see Figure 18.
"X" = The Step Value, is depending on which alarm algorithm that is
used, see Figure 17.
EBL128 Planning Instructions V1.1.x
Slow detection time (35sec.)
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during