Installation; Fault Contact; Wiring; Wiring Configurations - Bosch PRAESENSA Installation Manual

Loudspeaker line isolator system
4

Installation

The loudspeaker line isolator system can be installed on both new and existing loudspeaker
line installations.
Several conditions need to be met first to make all features work properly:
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4.1

Fault contact

Line isolator provides fault contact output per loudspeaker line for integration with any Voice
Alarm System via programmable control inputs. Every loudspeaker line can have separate
contact closure, or - depending on the system design - multiple loudspeaker lines can share
common fault contact.
The contact is normally open during quiescent mode of the system. During quiescent mode:
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Any other state, including service mode, amplifier disconnection or even power failure of Line
isolator, will immediately close the contact, reporting failure to the main system.
4.2

Wiring

The loudspeaker line isolator system can connect to solid-core wires or stranded wires with
conductor diameter of 0.8 - 2.5 mm2. The maximum current rating of the loudspeaker loop is
8 A RMS, which allows loading single 100 V line up to 800 W.
Fully functional when running on 2‑wire loudspeaker cable. For installations with special safety
requirements, its supports optional ground wire with open detection.
Maximum length of loop cabling is 1000 m. Maximum length of T‑Branch line is also 1000 m.
4.3

Wiring configurations

Figure 4.1: Single LDB wiring diagram
Bosch Security Systems B.V.
Main loudspeaker line has to be a closed loop.
T‑branch lines fitted with multiple loudspeakers require 47 kΩ EOL resistor for T‑Branch
open detection.
Every loudspeaker connected to Line isolator needs to be equipped with DC‑blocking
capacitor (typical value is 1 ~ 4.7 μF).
For 100 V installations maximum total load of single loop is 800 W, maximum single
T‑Branch load 50 W.
24 or 48 VDC power supply for LDB.
Line isolator system is powered and running, monitoring entire loudspeaker line.
Power amplifier is connected.
Loop is closed and fully working, every T‑Branch is fully operational.
No faults detected.
Installation manual
Installation | en 13
2021.07.28 | V1.00 |