Models S80 and S85 Power Overview
The models S80 and S85 power is provided to each rack type by independent power
supplies and distribution cabling. Both the system racks require 200 to 240 V ac power
connections. The system rack and the I/O rack have independent power distribution
systems.
System Rack Power
The power enters the processor system rack as 200-240 V ac. The line cord enters the
ac box, which contains two components; one is the ac filter and distribution assembly,
and the other supplies standby power to some system components. Standby power is
supplied to the operator panel interface and the System Power Control Network
(SPCN).
The filtered 200-240 V ac is then sent to the four (five on fully configured systems)
system bulk power supplies. The supplies are coupled together and provide an N+1
level of redundancy for protection. N+1 refers to the fact that because the supplies are
coupled to a common distribution bus, if one of the supplies fails, the system will not
fail. The bulk supplies provide a positive 29-volt output, which is fed to the system
regulator located above the bulk supplies and to the system blowers.
The system blowers maintain the system temperature within the strict guidelines
required in an N+1 arrangement. Each blower can be powered off individually so that a
blower can be removed and replaced without turning off the system power. The blowers
only require +29 V dc.
The system regulators provide 2.5 V dc and 3.3 V dc to the system.
I/O Rack Power
The I/O rack power-distribution network is shown in the illustration found under “I/O
Drawer Cabling” on page 41.
Power enters the I/O rack as 200-240 V ac through a power cable assembly and
terminates on a power distribution bus (PDB). The PDB has six individual ac outlets,
each capable of eight amps at 200-240 V ac, which are overload-protected and
resettable. Each I/O drawer is supplied from one ac outlet of the PDB through a special
“Y” cable. The “Y” cable draws power from a single PDB outlet and provides a standard
ac plug to each of the two power supplies used in each I/O drawer. Two I/O drawers
are allowed in each rack, but other type drawers can be installed in addition to the two
I/O drawers.
Ten EIA-unit I/O drawers have two redundant power supplies. One of these power
supplies is capable of providing the necessary voltages and currents independently of
the other. The left and right power supply output voltages are connected together and
monitored by the power distribution board contained in the 10 EIA-unit I/O drawer.
The left and right power supplies are hot-pluggable and may be changed one-at-a-time
while the system is operational. Each power supply provides 5 V dc, 3.3 V dc, 12 v dc,
and5Vdcstandby.
38 Service Guide
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