Bosch PRAESENSA, Руководство пользователя

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24 en | Installation wiring PRAESENSA
2021.12.21 | V0.15b | F.01U.402.882
Underwriters Laboratories Listing Document (ULLD)
Bosch Security Systems B.V.
3.2 Battery calculation
The PRAESENSA system includes multifunction power supplies, like the PRA-MPS3, to power
other PRAESENSA devices from the mains, but also from a battery in case of mains failures.
Each multifunction power supply uses its own battery.
3.2.1 Topology
Each PRA-MPS3 multifunction power supply has the capability to power up to three amplifiers
via 48 VDC, one system controller (or other device) via 24 VDC and a Call station via PoE. A
single 12 V battery is charged by the multifunction power supply to which it is connected. This
battery serves as a backup power source during mains failures. The required capacity of each
battery must be calculated separately for the PRA-MPS3 it is connected to, taking the load
into account that is served by this specific PRA-MPS3.
For the devices that are powered from a PRA-MPS3, it is important to notice that the power
consumption of each device may vary depending on operation modes and how it is connected.
When the power consumption has been calculated or measured, the corresponding battery
current draw (in case of a mains failure) can be calculated or measured. The power taken from
the battery will always be slightly higher than the power that is consumed by the device,
because of additional losses in the DC/DC converters inside the PRA-MPS3 that convert the
battery voltage to 48 VDC and 24 VDC.
3.2.2 Operating conditions
PRA-SCL
The power consumption of the PRA-SCL is relatively small, stable and hardly affected by
system activities. It is powered from the 24 VDC output of the PRA-MPS3. Only the number of
active Ethernet ports increases the power consumption.
PRA-CSLD | PRA-CSLW | PRA-CSE
The power consumption of the PRA-CSLD and PRA-CSLW is the same. Again, the power
consumption consists of a fixed part with an increment per active Ethernet port. Power is
supplied via PoE to one or both ports. Power is taken from the port that has the highest PoE
voltage. This means that if a call station is powered from two different PoE sources, like two
different PRA-MPS3 power supplies for additional redundancy, because of tolerances all of the
power may be taken from one of the power supplies. Only upon disconnection of that
Ethernet cable, the call station will take power from the other power supply. Even if both PoE
voltages 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.
Connecting PRA-CSE extensions to the call station will increase its power consumption
slightly, the increment depends on the number of LEDs that are on, but on average that
contribution is very limited because selections are only active during calls.
PRA-FRP3-US
The power consumption of the PRA-FRP3-US consists of a fixed part including two active
Ethernet ports as the PRA-FRP3-US must be installed with both Ethernet and PoE ports
connected. Power is taken from the port that has the highest PoE voltage. This means that if a
first responder panel is powered from two different PoE sources, like two different PRA-MPS3
power supplies for additional redundancy, because of tolerances all of the power may be
taken from one of the power supplies. Only upon disconnection of that Ethernet cable, the
first responder panel will take power from the other power supply. Even if both PoE voltages