3.2
Connection of Wired Zones
The signal cables of the zones are connected to the terminals “Z1”-“Z8”.
The common zone cables are connected to the “GND” terminals.
The plus power supply cables of the security zones (12 V) are connected to the “PWR” terminals.
The plus power supply cables of the fire zones (12 V) are connected to the “SMOKE” terminal.
3.2.1
Normally Closed and Normally Open Zone
The normal state of the zone is determined by its detectors:
∙
if the normal state for the zone is defined as
closed
, then there shall be detectors in this zone. which also
have
closed
contacts of their output relay in the normal state. In case of alarm, these detectors shall
open
the
contacts of the output relay;
∙
if the normal state for the zone is defined as
open
, then there shall be detectors in this zone, which have
open
contacts of their output relay in the normal state. In case of alarm, these detectors shall
close
the contacts
of the output relay;
It shall be noted that the vast majority of modern infrared and magnetic contact detectors have
normally closed
contacts of their output relay. Thus, for zones with these detectors, the normal state shall be defined as
closed
.
Normally open detectors are connected to the zone in parallel, and normally closed - in series.
One zone can include detectors of only one type: either normally closed, or normally open.
3.2.2
Terminating Resistors
If the terminating resistors are not used when connecting the zone, then for this zone the device can determine only
one of two states: “Alarm” or “Norm”. This zone is very vulnerable: if the normal state for the zone is defined as
open
, then it is very simple to cut the zone cable in any accessible location, and the zone will remain in the normal
state forever, there will never be any alarms on such a zone. The zone, which normal state is defined as
closed
, does
not look any better: if one can short-circuit the signal cables of the zone, then there will never be any alarms on it.
One terminating resistor, installed in the zone, allows to distinguish the failure in the zone from the alarm. What
kind of fault can be detected - break or short circuit - depends on the normal state of the zone: for the zone
open
normal state, one terminating resistor allows to determine the zone break, and for the
closed
normal state – short
circuit.
Two terminating resistors allow to determine both break and short circuit for a zone with any normal state.
For
minimum
counteraction against the alarm zone disabling, it is recommended to include at least one
terminating resistor in the zones.
3.2.3
Zone without Terminating Resistors
Figure 15: Normally open zone
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