NFS2-3030 Programming Manual — P/N 52545:K1 03/20/2012 123
Pre-Alarm Intelligent Sensing Applications
D.2.5 Cooperative Multi-Detector Sensing
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. Ion, photo and laser detector types can participate. Cooperative Multi-Detector
Sensing also allows the combination of ionization with photoelectric technology in reaching an
alarm decision. The figure below shows a graph representing Cooperative Multi-Detector Sensing:
Figure D.5 Cooperative Multi-Detector Sensing
D.3 Pre-Alarm
D.3.1 Definition
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 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 Appendix D.3.3, “Action Level”, on page 124)
Alert and Action Pre-Alarm settings
are set with point programming. Unique Pre-Alarm sensitivity
levels (PA) for individual detectors are listed in Appendix D.4, “Detector Sensitivity Settings”, on
page 124.
The LEDs on detectors polled in FlashScan mode will light s
teady green when in pre-alarm.
D.3.2 Alert Level
Alert Functions
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 a Pre-Alarm condition for the detector. The control panel does the following functions
when a detector reaches pre-alarm level:
• The Pre-Alarm message is sent to
the History buffer and to installed 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 LED flashes and the panel sounder pulses until acknowledged.
• Zone Z000 (general alarm) or any other zone and the System Trouble and System Alarm
relays do not activate.
SMOKE OBSCURATION
Time (minutes)
Alarm
Combined
3 Sensors
Awacs5a.cdr
To Next Page
Loading...
Need help?
General
