Service Manual

GSM-204-323
Control and alarm board (CAB)
31st Oct 01
Tech. 4–18
Technical Description: Horizon macro outdoor
CONTROLLED INTRODUCTION
68P02902W02-A
CAB control
functions
The CAB has the following control functions:
 Voltage trim.
 TOPSM disable relay control.
 Control of contactors during power up.
 Low voltage disconnect (LVD).
 Over temperature trip.
 Smoke trip.
Voltage trim
The CAB generates the control signal voltage (V trim) used to regulate TOPSM
output to produce a temperature-compensated battery charging voltage. The
temperature sensor is mounted on the CAB for internal batteries, and mounted
in the auxiliary equipment housing for external batteries. A dip switch on the
CAB (SW2–8) is used to select either internal or external battery temperature
sensing.
TOPSM disable relay control
On detection of an over temperature trip alarm or a smoke alarm from the BTS
cabinet, the CAB energises the coil of the TOPSM disable relay, interrupting the
enable in signal and shutting down the TOPSM –55 V outputs. The TOPSM
disable relay will remain energized until the alarm condition has cleared and, in
the case of a smoke alarm longer than 30 seconds, the cabinet ac supply has
been cycled or the CAB front panel reset switch has been operated. Operation
of the CAB front panel override switch will interrupt this function, for a 30 second
period, to allow fault diagnosis to be performed.
Control of contactors during power up
The CAB monitors the following signals during power up of the Horizon macro
cabinet:
 TOPSM auxiliary voltage within 9 to 15 V dc range
 Cabinet over temperature alarm.
 Cabinet smoke alarm.
If the alarm signals are inactive, the CAB will close the battery and
communications contactors, to supply customer communications equipment and
charge the backup batteries.
If the CAB detects a cabinet over temperature or cabinet smoke alarm during
power up, then the TOPSM disable relay operates, as described in TOPSM
disable relay control in this section.