Pre-Alarm Warning Mode of Operation
3. Operation of the Control Panel
NFS-640 Operations Manual P/N 51334:B 10/03/2003
31
Pre-Alarm Warning Mode of Operation
How the Control Panel Indicates a Pre-Alarm Warning
The control panel activates a Pre-Alarm Warning if a detector exceeds the programmed Pre-Alarm Alert
or Action level. When a detector activates a Pre-Alarm, the control panel does the following:
•
Pulses the panel sounder
•
Flashes the
PRE
-
ALARM
LED
•
Activates the Pre-Alarm zone (F9)
•
Sends a Pre-Alarm message to the LCD display, History buffer and installed printers, terminal
mode LCD-80s, and CRT-2s
•
Displays a
PREALARM
status banner, the Type Code of the detector, and the Pre-Alarm level
(Alert or Action) on the LCD display, along with information specific to the device as shown
in Figure 13.
How to Respond to a Pre-Alarm Warning
Pre-Alarm Alert and Action Levels
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. The Pre-Alarm function provides one of two
levels of Pre-Alarm as follows:
Note:
For detailed information on Pre-Alarm applications, refer to the
NFS-640 Programming Manual.
•
Alert – a non-latching condition that causes a Pre-Alarm when a detector reaches the
programmed Pre-Alarm level.
•
Action – a latching condition that causes a Pre-Alarm when a detector reaches the programmed
Pre-Alarm level.
Responding to a Pre-Alarm Warning
The Pre-Alarm screen display is the same for both alert and action conditions. Following is a sample
screen for a Pre-Alarm message.
Figure 13 Sample of an Alert Pre-Alarm Message
An Alert Pre-Alarm automatically restores to normal when the detector sensitivity, programmable to
one of nine settings, drops below the programmed Alert level. Zone F09 automatically clears when no
Pre-Alarm conditions exist.
An Action Pre-Alarm latches until you reset the system - even if the detector sensitivity drops below the
Action level. Zone F09 activates - but Zone Z00 (general alarm) and the trouble and alarm relays do not
activate. The fifth zone programmed, not the first four, in the detector’s CBE activates. A subsequent
alarm condition for this detector clears the Action indication from the LCD display.
Interpreting Pre-Alarm Type Codes
The Type Code that displays in the Pre-Alarm warning indicates the function of the point that initiates
the Pre-Alarm warning. Refer to the Detectors section of Table 4 for the Type Codes that can appear in
a Pre-Alarm warning, and for descriptions of those Type Codes.
Detector programmed for a Pre-Alarm level of 4
Shows the detector has reached 55% of the
programmed Pre-Alarm level. The 55% is a
real-time display and tracks smoke levels
Status banner
Type Code
PREALM SMOKE(PHOTO) INTENSIVE CARE UNIT
EASTERN WING
055%/4 03:20P 071401 1D147
Custom descriptor for
this device location
Device address
Time and date of trouble
Extended 12
character
custom label
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