$
HQGL[ & $:$&6 $
OLFDWLRQV
Pre-Alarm
76 AFC-600 Programming PN 51032:A 3/8/99
&RR
HUDWLYH0XOWL'HWHFWRU6HQVLQ
Cooperative Multi-Detector Sensing is the ability of a smoke detector to consider
readings from nearby detectors in making alarm or pre-alarm decisions. Each detector
can include up to two other detectors in its decision. Without statistical sacrifice in the
ability to resist false alarms, Cooperative Multi-Detector Sensing allows a detector to
increase its sensitivity to actual smoke by a factor of almost 2 to 1. Cooperative
Multi-Detector Sensing also allows the combination of ionization with photoelectric
technology in reaching an alarm decision. Figure 83 shows a graph representing
Cooperative Multi-Detector Sensing:
)LJXUH &RRSHUDWLYH 0XOWL'HWHFWRU 6HQVLQJ
3UH$ODUP
'HILQLWLRQ
The Pre-Alarm function is a programmable option which determines the system’s
response to real-time detector sensing values above the programmed setting. Use the
Pre-Alarm function if you want to get an early warning of incipient or potential fire
conditions. There are two levels of Pre-Alarm:
• Alert (Refer to “Alert Level” below)
• Action (Refer to “Action Level” on page 77)
Alert and Action Pre-Alarm settings are global. For instance, if you program Pre-Alarm
for Alert, all intelligent detectors programmed for Pre-Alarm are set to Alert (refer to
"How to Select a Pre-Alarm Level" on page 78). You can, however, set unique
Pre-Alarm sensitivity levels (PA) for individual detectors (refer to "Detector Sensitivity
Settings" on page 79).
$OHUW/HYHO
$OHUW )XQFWLRQV
The control panel software, in addition to checking for alarm levels, checks for
Pre-Alarm thresholds for each addressable, intelligent smoke detector programmed for
Pre-Alarm. If a detector’s real-time sensing level exceeds the programmed Alert
threshold, the control panel indicates an Alert condition for the detector. The control
panel does the following functions when a detector reaches pre-alarm level:
• The Alert message is sent to the History buffer and to any installed terminal mode
LCD-80s and printers. The message is sent (and time stamped) at the time that it
first occurred. This historical data could provide valuable information about the
progress of a fire.
• The
PRE
-
ALARM
WARNING
LED flashes and the panel sounder pulses until
acknowledged.
• Zone F9 activates—but Zone 00 (general alarm) or any other zone, or System
Trouble relay or System Alarm relay do not activate.
Continued on the next page...
Technical Manuals Online! - http://www.tech-man.com
To Next Page
Loading...
Need help?
General
