Tyco F3200 - Basic Principles of a Fire Alarm System

F3200 Operator's Manual Document No: LT0119
System Description
Page 2-2 29 July 2002 Issue 2.04
2.1 BASIC PRINCIPLES OF A FIRE ALARM SYSTEM
2.1.1 DETECTORS & ALARM ZONE FACILITY
A fire alarm system has sensors (electric transducers) which detect the presence of fire.
These include heat detectors (thermals), product of combustion detectors (smoke),
sprinkler system water flow switches, manual call points (break glass switches), and
others.
The building being protected is divided into areas of limited size called zones. The
detectors in each zone are connected to an electric circuit called an Alarm Zone Circuit
(AZC). The portion of the FIP which controls the AZC is called the Alarm Zone Facility
(AZF). In F3200 the 8 Zone Module does this. When a detector detects fire (i.e.
operates) it changes the electrical condition on the AZC and the AZF senses this (zone
alarm). The detector remains in the operated state (latches) until the AZF temporarily
removes the voltages to it (resets it). N.B. some detectors, e.g. flow switches, are non-
latching.
As well as sensing when a detector has operated the AZF can sense a fault in the AZC
wiring (zone fault).
The zone isolate function prevents a zone alarm or fault being registered by the Master
Alarm Facility (MAF). Refer to Fig 2.1.1.
2.1.2 ALARM VERIFICATION
When programmed (by the installer) to do so, the AZF may perform a verification
function on sensed alarms. This Alarm Verification (AVF) functions as follows:
When an AZF senses that a detector has operated, it does not register alarm
immediately but delays for a period of time and then resets the detector (typical total
delay is 11 seconds). If that, or another detector on the AZC operates within the next
150 seconds (or similarly programmed period) then the AZF recognises that as a verified
alarm, and generates alarm to the MAF.
2.1.3 DISPLAY
There is a display of zone status which allows the operator to see if a particular zone is
normal or is in alarm or fault, and if it is isolated.
There is also a separate display of common status which shows if any zone in the
system is in alarm, fault, or is isolated.