Installation Manual
6 Overview
Caption
[A] Loop
All the peripheral devices of the system must be connected in parallel to the loop circuit (2 pole STP).
The loop is a closed electrical circuit in which a wide variety of alarm devices can be accommodated.
Opening or closing the circuit at any point will generate a fault signal. The loop circuit communication
path starts on the Loop-Out terminals and ends on the Loop-In terminals. The panel controls and
communicates with the loop devices via digital protocol. The loop utilizes the same two poles for the
power supply to the system devices and the two-way communication channel.
The loop accommodates:
1. Detectors: A smoke detector is an active fire protection device that detects smoke or flames and
issues an alarm thereby alerting building occupants to the danger of fire.
Detectors can be:
- Optical smoke detectors which look for the presence of visible by-products of combustion in the
detection chamber (Tyndall effect).
- Optical/Heat detectors which operate as per optical smoke detectors but also sense for increase in
the environment temperature. The combination of both sensing methods (smoke and heat)
provides faster detection and reduces the false alarm rate.
- Heat detectors: sense for an increase in the temperature in the protected environment. There are
two types of heat detector: Fixed temperature — that signal alarm when the temperature exceeds
the predefined threshold; and Rate-of-rise — that as well as monitoring the predefined fixed
temperature also respond to rapid increase in temperature.
- Ionization smoke detectors: feature a harmless radioactive source within a dual detection
chamber. They operate by sensing for a change in electrical conductivity across the detection
chamber.
- CO detectors: sense the levels of carbon monoxide given off by all carbon-based materials in the
smouldering stages of a fire (often combined with heat detection sensor).
2. Input Module: a device which monitors the status of another device (callpoint, detector, etc.)
and sends the respective information to the panel. The Input module allows the loop to
accommodate any type of device.
3. Output Module: provides a supervised ancillary output. The cause of activation of this output
can be defined during the system configuration phase. The output module interfaces all types of
loop devices (bells, signaling devices, fire door magnets, etc.).
4. Callpoint: a clearly labeled fire button with instructions for use in the event of fire. Usually placed
near building entrances/exits. These push-button alarm-trigger devices allow building occupants
to activate system alarms.
5. Sounder/Flasher: audible/visual alarm signaling devices. The cause of activation (alarm, pre-
alarm, early warning, etc.) can be defined during the system configuration phase.
For the list of the devices the loop accommodates, and for details regarding their wiring and operating
principles, refer to Appendix B and Appendix B.
The loop circuit configuration (as required by the local Fire code in force) is a fault-tolerant circuit
which, in the event of short-circuit or loop interruption, allows the panel to continue to communicate
and drive the elements on either side of the interruption.
[B] Isolator
In order to provide a fault-tolerant loop circuit that is Fire code compliant, isolator modules must be
installed in series with the loop circuit. Isolators modules detect short-circuit conditions and
consequently interrupt the loop circuit. If a short-circuit occurs, the two isolators adjacent to the
shorted section will open and split the loop in such way as to allow the panel to drive the elements on
either side of the interruption. No more than 32 detectors/devices should be installed between two
isolator modules.
Note: Many detectors/devices have built-in isolators and therefore do not require isolator modules.
Refer to Appendix B and Appendix B for further details.
To Next Page
Loading...
Need help?
General
