Specifications

RN: 5-89
RS3: Software Release Notes for P1 R4.2
Changes to RS3 Manuals
5. Divide the number of power supply modules, including any
redundant modules, by two.
Number of Housings Needed =
Number of Power
Supply Modules
2
6. Round up the r esulting number to the next higher whole number
to find the number of power supplies needed.
The limit is four power supply modules on one bus; one additional
module may be added for redundancy. For example, a DC Distribution
Bus configured as an A/B Bus and a load that requires four power
supply modules will require three System Power Supply Unit housings.
The third housing is added to meet redundancy requirements. The A/B
Bus configuration is considered one bus. For additional information, see
“Non-redundant Bus Configuration” on page 1 -2-20.
Description: Information under the heading “Power Supply
Redundancy” on page 1-2-14 was added.
Two types of power supplies can be used with the RS3 system :
D AC/DC Power Supplies
D System Power Supply Units
Because of differences in output voltages, the DC output for a System
Power Supply Unit cannot be connected to the same DC Distribution
Bus (Bus A or Bus B) as an AC/DC Power Supply. However, if either of
the redundant bus type configurations described below is used, one
power supply type can be used on the Bus A while the other type can
be connected on the Bus B.
AC/DC Power Supplies are ferroresonant. Their outputs are diode
isolated and can be connected in parallel to the same DC Distribution
Bus. The nominal output of a AC/DC Power Supply is 30 volts. T he
non-battery backup version weighs about 25 kg (55 lb) while the version
with a backup battery weighs about 31.75 kg (70 lb).
A System Power Supply Unit consist of a housing where the mains
supply voltage wiring terminates and can contain up to two removable
switch-mode power supply modules per housing. Because these units
have no battery backup capability, there must always be one additional
power supply module on a bus to serve a s a backup operation beyond
what is needed to supply the load. Each power supply m odule is diode
isolated so it can be connected in parallel with any of the other modules
and share the load. Each power supply module acts as a backup to the
others. T he voltage output for each module is about 26V. The housing
weighs about 5.7 kg ( 12.5 lb) and each power supply m odule weights
about 3.8 kg (8.4 lb). For additional information on System Power
Supply Unit specifications, see SV: 1-3.