IFS-2600 Fire Indicator Panel Section 4 Installation
DOC-01-009 27
AZF Description
The AZF's on the IFS-2600 are monitored and scanned by custom thick film hybrids. These hybrid IC's
significantly reduce the possibility of false alarms and improve product efficiency and reliability.
The total Alarm Zone loop resistance is the sum of the end of line resistor (EOLR 4K7) plus all the parallel
connected detector loads.
AZF Supervisory Current
The supervisory current flows through the external terminal AZF+ through the field cable and to the end of
line resistor (EOLR), returning to the panel at AZF- terminal. Parallel connected, across the 2-wire pair field
cable, are a number of the previously listed detectors. During the quiescent state there is essentially an
open circuit across the + and - terminals of the detector base. The maximum number of detectors that can
be installed on each AZF is dependent on the type of detector and is listed in the IFS-2600 ActivFire
®
listing.
In an alarm state, a 560-ohm resistor is connected across the detector base causing additional loop current
to flow. This is sensed by the AZF to produce an alarm output. Removal of the E.O.L. resistor (in a non
alarm state) or the interruption of the supervisory current will produce a fault signal in the AZF.
As described above, the level of current is used to define the status of the alarm zone: -
I = 3.5 mA and below FAULT
I = 4.0 - 5.0mA at 24V QUIESCENT
I = 16 mA to 40 mA (current limited) ALARM
The zone current is used by the hybrid IC to determine the condition of the zone as above. This
information is then transferred to the microprocessor for processing.
Overload Protection
Note: Refer to Specifications Section 4.2 for details.
Zone Overload Self Reset
If a zone is overloaded by an accidental short to earth on an AZF circuit, the zone will automatically shut
down and produce a fault. Once this happens the panel will automatically recheck the zone every 60
seconds and once the overload is removed, restore power and the fault will clear.
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