EQUIPMENT: FIRECLASS Prescient III WRITTEN BY: RKP
PUBLICATION: OMFCPRES3IN CHECKED BY: AP
ISSUE No. & DATE: 0 02/02/12
PAGE 8 of 43
3. Functional Description
Note: Please refer to Section 10 for PCB Layout
Diagram and Section 12 for Connection
Diagrams.
3.1 Detection Zones (Zone 1, Zone 2 &
Aux Zone)
Three detection zone circuits are provided. They are
monitored for Open Circuit Fault, Short Circuit Fault
and Alarm (Fire). The End-Of-Line device is
normally a 22uF capacitor (or 10k resistor if set to
Intrinsically Safe mode) but can be configured for
3k9 resistor via a DIL switch on the motherboard.
A maximum of 32 devices may be connected on
each zone (the actual number is dependent on the
type of detector used, see section 7).
Manual Call Points may only be connected to the
aux. zone.
In Automatic mode, zones 1 and 2 are normally
used together to produce First Stage (pre-activated)
and Second Stage (activated) fire alarms, resulting
in automatic extinguishant discharge („Double
Knock‟ or „Coincidence‟ Zones).
The auxiliary detection zone only provides a general
fire indication.
Operation of Fire Reset causes the power supply to
all three zones to be disconnected for 4 seconds to
reset any activated detectors.
The Display Board has Fire and Fault LEDs for
each of the zones.
The Display Board also provides User Controls for
disabling the monitoring of individual zones.
3.2 Manual Release Facility (MR &
Panel Mounted Call Point)
Two circuits are provided for operating the Manual
Release facility.
1. The fourth detection zone is used as a Manual
Release zone. It is monitored for Open Circuit
Fault, Short Circuit Fault and Alarm. The End-
Of-Line device is usually a 10k resistor but can
be configured for 3k9 resistor via a DIL switch
on the motherboard.
It gives a Second Stage alarm in both
automatic and manual modes, and initiates the
Extinguishant release sequence when
activated.
This zone must only have manually operated
devices connected to it e.g. Manual Call Points.
The power supply to this zone is not switched
off during panel Reset.
2. A Manual Release Call Point is mounted on the
door of the panel and is monitored by a
separate circuit for open & short circuit faults.
The connection for the call point is on the rear
of the display board.
The Display Board has Activated and Fault LEDs for
the Manual Release facility, common to both
circuits. Individual fault LEDs are provided on the
motherboard inside the panel.
The Manual Release facility can be disabled,
resulting in both circuits being disabled.
3.3 General Alarm Circuits (SNDR1 &
SNDR2)
Two fully monitored general alarm circuits are
provided. They are monitored for Open Circuit and
Short Circuit faults. They are rated at 0.5A
(electronically fused), 28VDC each. The End-Of-
Line device is a 10k resistor (3k9 can also be used).
The Fire Sounder Fault/Disabled LED on the display
flashes for any fault conditions on the General
Alarm Circuits. Individual fault LEDs are provided on
the motherboard inside the panel. Both circuits can
be disabled as a group.
Note: The circuits are reverse-polarity monitored.
The PCB terminals are marked for the active
polarity. Ensure that all connected devices are
polarised.
3.4 Extinguishing Alarm Circuit (EXT
SNDR)
One fully monitored extinguishing alarm circuit is
provided, monitored for Open Circuit and Short
Circuit faults. It is rated at 0.5A (electronically
fused), 28VDC. The End-Of-Line device is a 10k
resistor (3k9 can also be used).
The Circuit Fault LED on the display flashes for any
fault condition on the Extinguishing Alarm Circuit,
with an individual fault LED on the motherboard
inside the panel. The circuit can be disabled by
disabling the extinguishing system (the Actuators
are also disabled at the same time).
Note: The circuit is reverse-polarity monitored. The
PCB terminals are marked for the active polarity.
Ensure that all connected devices are polarised.
3.5 Actuator Circuits (ACT1 & ACT2)
Two fully monitored actuator circuits are provided.
They are monitored for Open Circuit and Short
Circuit faults (short circuit fault indication can be
disabled). They are rated at 1A (fused), 28VDC
each. The End-Of-Line device is a 10k resistor (3k9
can also be used).
The Circuit Fault LED on the display flashes for any
fault condition on either Actuator Circuit, with
individual fault LEDs on the motherboard inside the
panel. Both circuits can be disabled by disabling the
extinguishing system (the Extinguishing Alarm
circuit is also disabled at the same time).
Note: The circuits are reverse-polarity monitored.
The PCB terminals are marked for the active
polarity. Ensure that all connected devices are
polarised.
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