Bosch PRAESENSA Installation Manual page 46

46 en | System composition
part should not be taken into account for the heat generation. Only the difference between
the power that is taken from the power supply and the output power to the loudspeakers is
actually dissipated as loss in the amplifier and contributes to the heat production.
When the PRAESENSA system is powered via multifunction power supplies (PRA-MPS3), also
some power is dissipated in the AC/DC power converters that convert power from the mains
to DC voltages for the connected devices. The amplifiers and the power supplies are the only
devices that contribute significantly to the heat production, the contribution of other
PRAESENSA devices is negligible. It is easiest to incorporate the losses of the power supplies
into the power dissipation data of the amplifiers. Because the normal situation is that the
system is running from mains power, this is the operational mode to consider for heat
calculations. During operation from a battery, the system switches to a power saving mode
(sleep mode or snooze mode), on average resulting in less heat.
The table below then shows the heat loss related data for the amplifiers, in different operating
modes.
Device
PRA-AD604
PRA-AD608
This data can be further simplified by assuming that in most systems the amplifiers are used
for background music and occasional calls, that full power alarm tones have a relatively short
duration (less than an hour) and that the heat production of the PRA-AD604 and PRA-AD608 is
not so different. Then the following rounded numbers are sufficient for heat loss calculation.
Just count the number of amplifiers in the rack or room for which the heat production must be
calculated and use the data from the table below.
Per amplifier
When amplifiers are powered from a PRA-PSM48 power supply, also the heat loss of that
power supply can be ignored, because it is already included in the heat loss of the connected
amplifier.
2019.11 | V1.00 |
Mode
Amplifier (active, idle)
Amplifier (active, low power)
Amplifier (active, full power)
Amplifier (active, idle)
Amplifier (active, low power)
Amplifier (active, full power)
Dissipated power
[W]
100
Installation manual
Dissipated Heat loss
power [W] [kJ/h]
39 140
64 230
100 360
48 173
88 317
124 446
Heat loss Heat loss
[kJ/h] [BTU/h]
360 340
PRAESENSA
Heat loss Heat loss
[BTU/h] [kcal/h]
133 34
218 55
341 86
164 41
300 76
423 107
Heat loss
[kcal/h]
90
Bosch Security Systems B.V.