Specifications

RN: 5-92
RS3: Software Release Notes for P1 R4.2
Changes to RS3 Manuals
modules (with two or more located in the same or a separate housing)
are connected to Bus A to supply the load. T here m ust be power
supplies connected to Bus B that are capable of supplying the same
load and at the same voltage. When only one power supply is needed
on each bus, the system must be wired for a single non -redundant bus.
See “Non-redundant Bus Configuration” for more information.
Return Bus
Bus A
Bus B
DC Bus to DC Bus
Jumper
Bus A
Return Bus
Bus B
Bus A/B Power Supply Modules (up to 4)
+--+-- +-- +--
PS1PS2PS1PS2
System Power
Supply Unit 1
System Power
Supply Unit 2
Figure 1.2.8. Redundant DC Power Distribution System for System Power Supply Units
It is not necessary that each bus (A and B) have a separate redundant
power supply module. Normally, bus redundancy eliminates that need.
A minimum of two and a m aximum of four power supply modules are
needed on Bus A. An equivalent supply must be provided on Bus B for
redundant bus distribution. Buses A and B using the System Power
Supply Unit are rated at 18--26 VDC.
All DC power source inputs m ust be individually isolated from each
other by using output diode isolation to p revent a back-drive condition
into a power supply that has lower output voltage. Output diode isolation
has been built into the power supply modules.
Power supply modules have over-current and over-temperature
protection. When you provide power supplies for Bus B, we recommend
an output rating of 24--26 volts. you must provide over-current
protection for the power sources placed on Bus B. Base the amount of
over -current protection on the total loading for which Bus A power
supplies are sized. When you supply redundant power on Bus B,
ensure that the power supply modules are diode isolated to prevent
them from being driven in the reverse direction. User -supplied power
source(s) must contain over-current protection and each source must
be individually protected. Here are three case examples: