Bosch Plena - Page 32

Bosch Security Systems | 2006-06 | 9922 141 10377 en
Plena Voice Alarm System | Installation and User Instructions | Equipment en | 32
If it is necessary to detect the removal or failure of a
single loudspeaker, the following is advised:
• Do not connect more than 5 loudspeakers to the
same loudspeaker line (line A or line B). Field tests
have shown that the impedance of loudspeakers and
loudspeaker lines varies with temperature and age.
The limit of 5 loudspeakers is set due to this
variation. In a more stable environment, the number
of loudspeakers can be higher.
• Make sure that all loudspeakers connected to the
same loudspeaker line have the same impedance.
5.3.7 Volume overrides
The voice alarm controller has 6 override outputs; 1 for
each zone in the system (see figure 5.9). These are
suitable for 4-wire override (24 V) and 3-wire override.
Note
The impedance measurement of the Plena Voice
Alarm System has an accuracy better than 2%.
The system only generates a fault if the line
impedance difference is greater than the
configured accuracy. Use the configuration
software to configure the accuracy.
Note
See the Configuration Software Manual
(9922 141 1038x) for more information about
the configuration software.
Note
The maximum load for the internal power
amplifier of the voice alarm controller is 240 W.
However, if the voice alarm controller is used in
2-channel mode and an external 480 W
amplifier is connected to it, the maximum
loudspeaker load can be 480 W at 100 V. This
is because in 2-channel mode, the internal
power amplifier of the voice alarm controller is
used for BGM only and distributes BGM at
-3 dB, from which follows that the maximum
power output is 240 W at 70 V and that the
loading caused by 100 V loudspeakers at 70 V
is also 240 W. The external amplifier is used for
calls only with 480 W output power and 100 V
loudspeaker line voltage.
Note
By default, the voice alarm controller is
configured for 4-wire (24 V), power-saving
override, see situation I in figure 5.11.
figure 5.9: Override outputs
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