NFS2-640 Operations P/N 52743:L4 06/10/19 39
Operation of Special System Timers Operation of the Control Panel
The LCD display shows the current selections for System Functions, which includes the three sys-
tem timers.
Sample LCD display of a System Function screen with system timer selections:
Figure 3.3 Sample System Function Selection Screen
3.14.3 How System Timers Work
The control panel can operate with special system timers: Auto Silence Timer, Alarm Verification
Timer and Silence Inhibit Timer.
Auto Silence Timer
A timer that functions like pressing the SIGNAL SILENCE key. When the Auto Silence Timer reaches
its programmed value (600-1200 seconds), the control panel automatically shuts off all active out-
puts programmed as silenceable.
When Auto Silence activates, special function zone ZF40 will activate and remain active until a
system reset alarm resound or drill (alarm signal for Canadian applications) is initiated.
Activation of Auto Silence will activate the Signal Silence LED on the fire panel display and any
ACM LED point programmed for Auto Silence.
NOTE: In Canadian applications, if auto silence is enabled, the value must be set to 20 minutes.
An ACS point is required to monitor special function zone ZF40.
Alarm Verification Timer
A timer that directs the control panel to ignore a fire alarm for a smoke detector, programmed for
Alarm Verification, while the Alarm Verification Timer is counting. Table 3.9 contains a summary
of how the Alarm Verification Timer works.
Silence Inhibit Timer
A timer that disables the SIGNAL SILENCE key function and inhibits reset during countdown for the
programmed time (0-300 seconds) when a fire alarm occurs. A Silence Inhibit Timer starts at the
first fire alarm. Subsequent alarms will not restart the timer until the alarm condition is completely
resolved and a panel reset is performed.
Silence Inhibit Timer set to 180 seconds
Auto Silence Timer set to 600 seconds
Alarm Verification Timer set to 30 seconds
SIL INH=180 AUTO=600 VERIFY=30 USA TIME
TERM=N AC-DLY=Y LocT BLINK=01 ST=4 ACS=N
If The control panel does this
A second fire alarm occurs while the
Alarm Verification Timer is counting
Ignores the Alarm Verification Timer
The Alarm Verification Timer elapses and
a fire alarm still exists
Activates the fire alarm
The Alarm Verification Timer expires and
a fire alarm no longer exists
Increments the Alarm Verification counter (up to 99)
for the device and returns to normal operation
Table 3.9 Alarm Verification Timer Operation
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