Bosch Plena Operating Manual page 57

Plena
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
See situation II, for an example of a fail-safe 4-wire volume override:
4
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.
2.
3.
Bosch Security Systems B.V.
Connect the NO contact of the Volume Override to the 24V contact of the Volume
Override.
Connect the NC contact of the Volume Override to the 24V contact of the Volume
Override.
Override/Trigger Output
24V
NC
Z1
COM
NO
Z2
NC
COM
Z3
NO
NC
Z4
COM
NO
Z5
NC
24V
Z6
NO
G 1
TRG2
Override/Trigger Output
24V
NC
Z1
COM
NO
Z2
NC
COM
Z3
NO
NC
Z4
COM
NO
Z5
NC
24V
Z6
NO
G 1
TRG2
Connect the 100 V output of loudspeaker line A to the 100 V input of the volume control.
Connect the 100 V/0 V (CALL/RTN) of the transformer to the 100V output of loudspeaker
line B.
Connect the 0 output of loudspeaker line A to the 0 V of the loudspeaker.
Installation and Operation manual
100V
NC NO
EM
COM
Fault
0V
Call
Z+
Volume Override
Z-
100V
NC NO
EM
COM
Fault
0V
Call
Z+
Volume Override
Z-
Connection | en 57
NC
NO
NO
NC
2013.07 | V2.0 |