Safety Ground; Power Supply - Bosch PRAESENSA Installation Manual

86 en | Amplifier, 600W 8-channel | PRA-AD608
9.5.2

Safety ground

Connecting the chassis ground screw to safety ground is mandatory for the PRAESENSA
power amplifiers:
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Caution!
The chassis ground screw of an amplifier must be connected to protective ground before the
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amplifier is connected to a power supply.
9.5.3

Power supply

The amplifier must be powered from a 48 V power supply. If the amplifier is used as part of a
certified emergency sound system, it must be powered from a PRAESENSA multifunction
power supply. In case the amplifier and the power supply are mounted in two different racks,
double power supply connections must be made, but even if both devices are in the same
rack, it is recommended to use double connections for fail-safe redundancy.
2019.11 | V1.00 |
The safety ground connection is needed for safety because of high internal voltages. All
PRAESENSA 19"‑devices have a chassis ground screw on the rear panel, which can be
used for a wire connection to the rack frame. The rack frame must be grounded to safety
ground. This is a conductive path to ground or earth that is designed to protect persons
from electrical shock by shunting away any dangerous currents that might occur due to
malfunction or accident. Use a thick, multi strand wire (>2.5 mm
washers for a solid connection.
The safety ground connection is needed as reference for the ground short detection
circuit. Without this connection, the amplifier could be electrically floating and no ground
shorts or leakage currents would be detected for loudspeaker lines that touch ground
somewhere. The safety ground connection via the mains connection of the multifunction
power supply cannot be relied on for this, because the mains cable of this supply could
be unplugged and then the amplifier continues to work on the backup battery.
Installation manual
PRAESENSA
2 ) with wire eyelets and
Bosch Security Systems B.V.