User's Manual Part 1

March 29, 2006 Part ######A revision 00a-DRAFT 27
Chapter 2: Site Preparation
Base Station Power Supply Circuit Breakers
The customer’s –48V DC power supply must be equipped with six circuit breakers to power the base
station rack equipment. Table 2.15 shows the required sizes of circuit breakers on each of the three
power feeds to each rack.
Base Station Power Supply Grounding
The return lead on the base station power supply shall be connected to earth ground as close as
possible to the –48V DC source (for example, the rectifier or DC–DC converter). For fault
protection, the earthing conductor shall be sized in accordance with applicable regulations to carry the
the current of the largest power source circuit breaker (either 35A or 50A). Since this is a
negative-supply positive-ground system, the return lead is the one with the most positive potential of
the active conductors, –48V and DC return.
Backup Power
The base station does not contain any internal battery backup systems. Ensure that your main power
source has a backup power system in case of a power failure.
Fuses
Each RFSS module contains one 2A, 250V, fast-blowing fuse (1.25 × 0.25 inch) to protect the RF
components from damage in the event of an electrical overload.
Rack Grounds
Table 2.16 shows the grounding requirements for each rack.
3.5 GHz 6 sectors 40 106 146 7425
3 sectors 24 55 79 3990
1 sectors 14 21 35 1785
Rack Circuit Breaker Size
Radio rack 35A
RF rack 50A
Table 2.15 Power Bay Circuit Breaker Sizes (–48V)
Version Configuration Radio Rack (A) RF Rack (A) Total (A) Total (W)
Table 2.14 Power Consumption Values (–48V)
Ground Type Requirement
Frame ground Each rack requires one connection to its frame assembly for use as a frame ground. The frame
ground cable uses #6 AWG wire.
Main ground Each rack requires one connection to the main building ground, such as the master ground bar
(MGB). The ground cable uses #6 AWG wire.
Isolation pad Each rack must be installed on an isolation pad to ensure proper grounding. The isolation pads
are included in the installation kit.
Table 2.16 Grounding Requirements