Bosch Plena - Page 57

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+).
See situation I, for an example of a power-saving 4-wire volume override:
4 Connect the NO contact of the Volume Override to the 24V contact of the Volume
Override.
See situation II, for an example of a fail-safe 4-wire volume override:
4 Connect the NC contact of the Volume Override to the 24V contact of the Volume
Override.
CO M
NC
NO
NC
TRG2
Override/Trigger Output
G 1
24V
EM
Fault
Call
Z1
Z2
Z3
Z4
Z5
Z6
NC
COM
NO
NC
COM
NO
NC
COM
NO
NO
24V
Volume Override
100V
0V
Z+
Z-
NO
NC
CO M
NC
NO
NC
TRG2
Override/Trigger Output
G 1
24V
EM
Fault
Call
Z1
Z2
Z3
Z4
Z5
Z6
NC
COM
NO
NC
COM
NO
NC
COM
NO
NO
24V
Volume Override
100V
0V
Z+
Z-
NC
NO
Figure 5.9: 4‑wire volume override
To create a 3‑wire volume override:
Notice!
It is not possible to use 3‑wire volume override in combination with redundant loudspeaker
lines (line A and B, see figure 5.6) and supervision. If redundant loudspeaker lines are
needed, use 4‑wire volume override.
1. Connect the 100 V output of loudspeaker line A to the 100 V input of the volume control.
2. Connect the 100 V/0 V (CALL/RTN) of the transformer to the 100V output of loudspeaker
line B.
3. Connect the 0 output of loudspeaker line A to the 0 V of the loudspeaker.
Plena Connection | en 57
Bosch Security Systems B.V. Installation and Operation manual 2013.07 | V2.0 |