Bosch Plena LBB1990/00, System Manual

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Plena Voice Alarm System | Basic System Manual | Installation en | 21
3.11 Volume overrides
The voice alarm controller has 6 override outputs; 1 for
each zone in the system (see figure 3.8). These are
suitable for 4-wire override (24 V) as well as for 3-wire
override.
Internally, the positive override pins (
Z+
) are all
connected to either the
NC
or the
NO
contact of the
Volume Override output (see figure 3.9). The negative
override pins (
Z-
) are all connected to earth.
Normally, when there are no active calls, the Z+ pins
are internally connected to the
NC
contact of the
Volume Override . At the moment a call is started in a
zone, the Z+ pin of the zone is internally connected to
the
NO
contact of the
Volume Override
. So, the
NC
and
the NO contacts determine which voltage is supplied to
the positive pins of the override outputs (
Z+
).
Note
By default, the voice alarm controller is
configured for 4-wire (24 V), power-saving
override, see situation I in figure 3.10.
figure 3.8: Override outputs
LBB1990/00
COM
NC NO
NC
TRG2
Override/Trigger Output
TRG 1
24V
EMG
Fault
Call
Z1
Z2
Z3
Z4
Z5
Z6
NC
COM
NO
NC
COM
NO
NC
COM
NO
NO
24V
Volume Override
figure 3.9: Volume override contacts
Z1
+
_
Z2
+
_
Z3
+
_
Z4
+
_
Z5
+
_
Z6
+
_
NO NC