PRAESENSA
Installation wiring | en
25
Bosch Security Systems B.V.
Underwriters Laboratories Listing Document (ULLD)
2021.12.21 | V0.15b | F.01U.402.882
are the same, using one short cable and one long cable may result in that most of the power is
taken via the shortest cable because then the voltage drop across the wire resistance of each
cable is equal.
During a trouble condition, the sounder of the first responder panel is activated as an audible
trouble alarm. The power consumption of the sounder during mains absent must then be
taken into account because the fault may not be acknowledged resulting in an activated
sounder during the standby time.
PRA-AD604 | PRA-AD608
The PRA-AD604 and PRA-AD608 amplifiers are designed for low power consumption,
especially when powered from a battery, by incorporating different modes of operation.
When the mains voltage on the PRA-MPS3 fails, it switches to the battery to take power from.
The PRA-MPS3 notifies the amplifier of this and when the amplifier doesn’t have to make
announcements of high enough priority, it will go into sleep mode or snooze mode and notifies
the PRA-MPS3 to switch off the 48 VDC power section to this amplifier. The amplifier then
operates directly from the battery via the lifeline interconnection. In sleep mode the power
consumption is lowest but there is no amplifier and loudspeaker line supervision active. When
supervision has been enabled (as required for UL864 and UL2572 compliancy) for this
amplifier, the amplifier will go into snooze mode, which is a combination of being in sleep
mode for most of the time, but waking up into idle mode to perform a supervision cycle for a
few seconds every 90 seconds. The average power consumption in snooze mode is somewhat
larger than in sleep mode. When a call is being made or a tone played to one or more of the
channels, the amplifier immediately requests the PRA-MPS3 to switch on the 48 VDC power
supply again and the amplifier will operate from the normal supply voltage. The power
consumption of the active amplifier will then vary between the value for low power (small
signal audio or small loudspeaker load) and full power (audio in full load at maximum level).
In all modes, the power consumption of the active Ethernet ports must be taken into account.
Because the PRA-AD608 has nine amplifier channels, while the PRA-AD604 has five channels,
the power consumption of the PRA-AD608 is slightly higher than of the PRA-AD604.
PRA-ES8P2S
This Ethernet switch has a dual 48 V DC-inputs.
The switch is powered by the PRA-MPS3 and the 48 V output that is powering the switch
should not be used to also power an amplifier.
The lifeline that belongs to the powering 48 V output is not used. In case of mains failure the
switch will be powered from the battery, connected to the multifunction power supply.
The power consumption of the switch is highly dependent on the number of ports that are in
use and whether these ports provide PoE power to connected devices. Next to the power
consumption of the switch itself and the power consumption of the active ports, the PoE
loads of all ports together (expressed in watt) multiplied by 0.1 gives the approximate
additional load of the battery (expressed in ampere). Please note that a call station that is
connected to this switch and powered via PoE from this switch will load the battery slightly
more than when the same call station would have been directly powered from a PoE port of
the PRA-MPS3, because the switch in between has some 20% additional losses.
PRA-MPS3
The power consumption of the PRA-MPS3 itself is mainly determined by its network interface
and the number of active Ethernet ports (RJ45 or SFP). For the battery capacity calculation,
the power loss of the DC/DC converters to supply power to all connected devices is already
taken into account in the power taken from the battery by these devices. The power
consumption of the relays of the control outputs is insignificant.
