Installation Instructions

–48 V DC P ower Supply Module (PSM) Shelf Chapter 10: PSM Shelf R eplacement Procedures

–48 V DC Power Supply Module (PSM) Shelf

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–48 V DC PSM Shelf Description

The –48 V DC P ower Supply Module (PSM) shelf is optional. It is used to convert –48 V DC

input power to +27V DC output operating power for distribution to the UBS Macro BTS frame

electronics.

The –48 V DC PSM shelf is located at the bottom of the UBS Macro BTS frame. Figure 1 -1 UBS

Macro BTS low -tier/low -capacity frame (1000 mm rack) on page 1 - 27 , Figure 1 -2 Low capacity

UBS Macro BTS starter frame (1800 mm rack) on page 1 - 28 and Figure 1 -3 UBS Macro BTS

mid -capacity frame (1800 mm rack) on page 1 - 30 show the location of the –48 V DC PSM shelf

within the UBS Macro BTS frame.

Figure 1 -15 –48 V DC and 220 V AC PSM shelves front panel detail on page 1 - 46 shows the

location of I/O port connectors and PSM slots on the front of the –48 V DC PSM shelf .

Figure 1 -16 –48 V DC PSM shelf rear panel detail on page 1 - 47 shows the location of input

connector and output cable on the rear of the –48 V DC PSM shelf .

The –48 V DC PSM shelf provides interconnection between the PSM slots DC I/O and the PSM

shelf DC I/O as well as interconnection between the PSM slots alarm/status I/O and the PSM

shelf alarm & control I/O .

The plug -in PSMs provide DC -DC conversion and +27V DC power output capabilities.

Up to three PSMs can be housed in the PSM shelf . A minimum of two PSMs are equipped for

redundancy . An empty PSM 3 slot is covered with a ﬁller panel.

PSM shelf plug -in modules

The –48 V DC PSM is a DC–DC converter . It operates from a nominal –48 V DC (–39 to –72 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 –48 V DC PSMs.

Three PSMs can provide a maximum of 8100 W , +27 V DC (+/– 0.1 V) output from the –48 V

DC PSM shelf .

Each PSM has internal fans that circulate cooling air from the front to the rear of the module.

Each PSM slides into a slot in the shelf . Blade type contacts, on the rear of the PSM, mate with

the DC I/O bus bar contacts in the PSM slot.

10 -2 68P09283A64 -3

FOA SEP 2007