User Manual

Axell Wireless Limited
Technical Literature
Lincoln/Holland Upgrade Equipment
Document Number
60
-
214701HBKM
Issue No.
1
Date
29/08/2008
Page
25
of
43
5. PSU and Battery Backup 60-214703
PSU and Battery Backup 60-214703 is built into a wall-mounted, environmentally protected (IP65)
aluminium alloy case; ports and connectors are also IP65 standard making the entire enclosure and
connecting ports weatherproof. The door is fitted with locking door handles and handles are provided
for carrying the unit. There are Power On and Alarm indicators on the outside of the door.
The power supply uses two identical 400Watt mains driven PSU modules connected via power
combining diodes to supply 24V DC power to the Remote site equipment. This wiring arrangement
allows either of the modules to supply power continuously should one of the PSUs fail. Both the PSU
modules are alarmed through a 12V relay PCB and will activate the main alarm should either module
fail. Mains trip switches isolate the AC supply to either PSU module should either need to be switched
off.
The battery backup system operates in parallel with the main AC derived DC supply from the PSU
Modules; thus if the primary AC fails the backup system provides a seamless “no-break” transition
from mains to battery. Four 12V, 38Ah Sealed Lead-Acid batteries are employed, arranged in two
pairs wired in series each pair providing a 24V Output. Pair 1 provides backup for Remote Repeater
60-214701 and Pair 2 provides backup for existing PCS Amplifier 60-004001. During normal
operation the AC mains float charge the batteries via a third mains driven PSU Module.
A Low Voltage Disconnect circuit exists which cuts the battery power to the equipment when the
battery voltage falls below a pre-set threshold. A series regulator circuit ensures that the DC voltage
from the fully charged batteries does not exceed 12V per battery.
All PSU modules are separately alarmed and the summed alarm data is presented at the connector
labelled “N” in section 5.3.2. from where it is fed to Remote Repeater 60-214701 for onward
transmission to the Master Site
5.1. PSU and Battery Backup 60-214703 Simplified Arrangement Sketch