2-8
The FACP is powered by the SPS (System Power Supply), which gets its primary power
from the AC mains and its secondary power from the backup batteries.
The 24Vdc bulk power on the SPS is unregulated, and is divided into three feeds, i.e. 24V
Card, 24V Signal, and 24V Aux Power. 24V Card which supplies the cards, and Aux
power, which is accessible on screw terminals, are each rated at 2A and protected by a
PTC. The 27.3V regulated battery charger is powered from the bulk supply and is
switched off during alarm. The batteries only get connected to the bulk supply when the
mains supply fails. The charger has two programmable options of rating, 1.4A for 6-
18Ahr (called little-uns), and 3.3A for batteries above 18Ahr (called big-uns).
The “heavy” 24V Signal feed is only accessible via the NACs on the SPS, or via a wire
harness.
IMPORTANT: AC power must be provided to the 4100U from a dedicated
branch circuit.
In expansion bays, power and data are distributed via the power distribution interface
(PDI). The PDI is a wiring board with eight card slots, each of which can accommodate a
4-inch (102 mm) x 5-inch (127 mm) slave card. If motherboards are used, they must be
mounted over the PDI using metal standoffs.
Standards cards, e.g. IDNet, plugged onto the PDI access only the 24V Card supply.
If an XSPS is plugged onto the PDI, then the 24V Signal Bus is also powered. This is
required for the 4100MXP which uses card power to power its electronics, but signal
power to supply the 40V loop.
4100 POWER DISTRIBUTION INTERFACE
ASSY 566-084
Figure 2-5. The Power Distribution Interface (PDI)
Introduction to FACPs (4100U), Continued
System Power
The Power
Distribution
Interface (PDI)
POWER/COMMS
CONNECTORS
(P1-P3)
AUDIO
INTERFACE
CONNECTORS
(P6, P7)
POWER SOURCE
JUMPERS
(P4, P5)