Edwards Signaling ReadySet - Manual (Page 35)

Chapter 3: Installation and configuration
ReadySET Aspirating Smoke Detection System Installers Handbook 27
Alarm factor
The detector calculates sensitivity relative to the ambient pollution level. Higher Alarm
Factors provide reduced sensitivity.
Note:
Changing the alarm factor starts a new FastLearn cycle.
Alarm factor: The ClassiFire system statistically analyzes the background smoke level
and sets detector sensitivity to a level giving a statistical probability of nuisance alarm.
The software assesses the arithmetic mean and variance (standard deviation) of the
“normal” ambient smoke level and places the alarm flags at a certain number of
standard deviations from the mean of the distribution.
The number of standard deviations at which the alarm flag is set away from the mean is
directly proportional to the ClassiFire alarm factor chosen.
The probability of nuisance alarm and the maximum detector sensitivity are higher when
a low level of alarm factor is chosen and lower as the alarm factor is increased. A low
alarm factor may be desirable in the case of a high-value computer center where the
cost of down-time and call-out costs may be offset by the high value of the protected
installation.
On the other hand, this will not be desirable in a machine shop with very variable levels
of background smoke. In this case, it may be more important to ensure that an elevated
level of smoke really does indicate an incipient fire before alarms are raised.
The probability of nuisance alarm for a given environment also depends on the
“stability” of the background smoke level. For example, a clean, controlled environment
will unlikely have a smoke level that will vary over time. Under these circumstances, a
low alarm factor will not imply a radically increased probability of nuisance alarm.
ClassiFire On
Selecting ClassiFire On allows the artificial intelligence system to continuously adjust
alarm thresholds in order to avoid unwanted alarms from environmental changes
(recommended).
Note:
Disabling this feature means that nuisance alarms due to fluctuations in ambient
pollution levels become more likely.
Fixed alarms
Switches the artificial intelligence system off, locking sensitivity to that set at initial
setup. This deactivates the dust filter monitoring system (not recommended).
Note:
Enabling this feature means that nuisance alarms due to fluctuations in ambient
pollution levels become more likely.