NFS2-640/E Programming Manual — P/N 52742:L2 7/17/14 99
Pre-Alarm Intelligent Sensing Applications
C.3 Pre-Alarm
C.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 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 100)
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 100). You can, however, set unique Pre-Alarm sensitivity levels (PA) for
individual detectors (refer to “Detector Sensitivity Settings” on page 101).
C.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 an 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 any installed FDU-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 LED flashes and the panel sounder pulses until acknowledged.
• Zone F9 activates—but Zone 00 (general alarm) or any other zone, System Trouble relay
and System Alarm relay do not activate.
• The Pre-Alarm indication for this detector will restore automatically to normal if its
sensitivity, programmable to one of nine settings, drops below pre-alarm level. Zone F09
clears automatically when no Pre-Alarm conditions exist.
• A subsequent alarm for this detector also clears the Pre-Alarm indication.
Example of an Alert Level
When an ion detector is programmed for AL:7 and PA:5 (covered in “Changing Detector
Sensitivity” on page 54), an Alert Pre-Alarm occurs at measured smoke detector levels that exceed
1.00% per foot obscuration. When this happens the panel sounder and the
PRE-ALARM LED pulse,
and a display appears on the LCD, similar to the sample screen shown below:
Figure C.6 Sample Display of a Pre-Alarm Alert Condition
Pre-Alarm status banner
84%/7 indicates that 84% of
Pre-Alarm level 7 is reached.
PREALM SMOKE (ION) DETECTOR ADDR 1D102
084%/7 02:55P 041508 1D102
To Next Page
Loading...
Need help?
General
