Installation Instructions

P ower Supply Modules (PSMs) Chapter 10: PSM Shelf R eplacement Procedures
220 V AC PSM Description
The 220 V AC PSM is an AC–DC power supply . It contains AC line input filtering and AC–DC
rectification. The rectifier output is applied to a DC–DC converter .
The 220 V AC PSM operates from a nominal 220 V AC (154 to 300 V) input and provides a 2700
W , +27 V DC (+/– 0.1 V) output. The output is designed to support load current sharing when
configured for parallel output operation with other 220 V AC PSMs. The PSM has internal fans
that circulate cooling air from the front to the rear of the module.
Each 220 V AC PSM slides into a slot in the 220 V AC PSM shelf . Blade type contacts, on the rear
of the 220 V AC PSM, mate with the DC output bus bars at the rear of the 220 V AC PSM shelf .
Each 220 V AC PSM has a rear panel AC input & status/alarm drawer connector that mates with
a bulkhead connector in the PSM slot of the 220 V AC PSM shelf . The AC line input buses in
the 220 V AC PSM shelf connect to the AC input lines of the AC input & status/alarm drawer
connector . The status/alarm I/O signals of this connector are interconnected to the ALARM &
CONTROL connector on the front of the PSM shelf . This connector is cabled to the S SI front
panel PSM connector . This allows the PSM alarm & status to be monitored by the S SI. It also
allows the front panel LEDs and module enable to be controlled by the S SI.
PSM alarm & status signal inputs are current share, temp alarm, converter fail, fan fail, high
temp, low bus voltage, input voltage loss, presence, and EID .
The current share signal goes directly from one PSM to the others via PSM shelf backplane
looping without going to the S SI. Based on PSM alarm & status, the S SI outputs signals to
control the state of the LEDs.
The PSM shelf ALARM & CONTROL cable also contains the PSM enable line which
must be grounded at the S SI in order for the PSM to operate.
System impact/considerations
This replacement procedure does not require system downtime. However , alarms may be
generated.
T wo PSMs provide N + 1 redundancy and load sharing for its respective PSM shelf . In the event
of a PSM failure, one PSM is capable of providing operating power for its respective PSM shelf .
However , a failed PSM should be replaced as soon as possible to maintain redundancy .
The PSM is hot–swappable.
Table 10 -5 FRU replacement conditions
FRU
Ref Designator What to Shutdown...
–48 V DC P ower
Supply Module
–48 V DC PSM
Nothing; FRU is hot swappable and redundant.
220 V AC P ower
Supply Module
220 V AC PSM
Nothing; FRU is hot swappable and redundant.
10 -18 68P09283A64 -3
FOA SEP 2007