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Bosch Security Systems | 2011-02
Praesideo 3.5 | Installation and User Instructions | 4 | Amplifiers en | 139
8.3.5.3 50 V output
The 50 V output provided by the amplifier channel is
actually a tap-off from the 50 V voltage for the
loudspeaker line. The availability of the 50 V line does
not depend on the selected loudspeaker voltage, since
the tap-off is situated in front of the jumper (see
figure 8.6).
If the 50 V is connected to ground, a ‘balanced’ output
for the loudspeaker voltage can be created. In that case,
the maximum voltage between the loudspeaker line and
ground is never more than 50 V (see figure 8.6). The
actual voltage between the loudspeaker line and ground
depends on the position of the jumper switch.
If the 50 V is connected to ground on purpose, the
ground supervision of the amplifier output should be
disabled using the configuration software (see
section 43.3.4).
8.3.5.4 Control outputs
Each amplifier channel has one control output. The
control output can be used to send signals to third party
equipment to trigger actions. Each control output has
three pins (see figure 8.4). The common (C) pin of the
control output should always be connected. Whether
the other pin that is connected is the normally closed
(NC) or normally open (NO) depends on which action
you want to take place when the control output is active
(see table 8.5).
In the configuration, a purpose must be attached to the
control outputs that indicates the action to be taken
when it becomes active (see table 43.6). For example,
the power amplifier control outputs can be configured
as a Volume override output to create volume overrides.
8.3.5.5 Spare amplifiers
If a power amplifier has a defect, all loudspeaker lines
are switched automatically to a spare amplifier (if
connected and configured). See figure 8.7 for a
connection diagram. Keep the following in mind:
• The main and spare power amplifiers must be of the
same type. If the main power amplifier is a
PRS-4P125, the spare power amplifier must also be a
PRS-4P125
• The way the loudspeaker lines are connected to the
spare amplifier must be exactly the same as the way
they are connected to the main amplifier. For
example, if the loudspeaker lines use the fixed 50 V
output of the main amplifier, they also must be
connected to the fixed 50 V output of the spare
amplifier.
figure 8.6: 50 V output
100 V
70 V
Spare In +
Lsp Out +
50 V
100 V
50 V
50 V
0 V
Spare In -
Lsp Out -
50 V
table 8.5: Control outputs details
Behavior Abbreviation Description
Normally
closed
NC By default, the NC
contact is connected
with common contact
C. When the output is
activated, the NC
contact is opened.
Normally
open
NO By default, the NO
contact is not
connected with
common contact C.
When the output is
activated, the NO
contact is closed.