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Praesideo 3.5 | Installation and User Instructions | 4 | Amplifiers
8.4
Fan control
The PRS-1P500, PRS-2P250 and PRS-4P125 amplifiers,
from HW version 06/00 onwards, have a fan
monitoring circuit that detects the actual fan rotation.
This detection is needed for compliancy to the standards
UL864 and UL1711, for use in the USA. Additionally
the internal fans need to run at full speed for
compliancy to these standards. A jumper on the main
PCB selects between two positions:
•
Normal (factory default) - The fans are temperature
controlled, normally running at low speed and
switching to high speed in case the temperature
exceeds a certain level. Fan monitoring is not
activated.
PRS-1P500, PRS-2P250 and PRS-4P125
figure 8. 1 5: Jumper X18 provides fan control for PRS-1P500, PRS-2P250 and PRS-4P125
Bosch Security Systems | 2011-02
•
Full speed - The fans run at full speed continuously.
Fan monitoring is activated. Do not enable Switch
amplifiers to standby (see section 44.4) for this
selection, because in standby the fans are stopped
and a fault would be generated.
The jumper is indicated on the PCB as X18; connection
1-2 selects Normal, connection 2-3 selects Full speed.
See figure 8.15.
en | 144
X18
3
2
1
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