Service Manual

GSM-204-323
Control and alarm board (CAB)
31st Oct 01
Technical Description: Horizon macro outdoor
68P02902W02-A
CONTROLLED INTRODUCTION
Tech. 4–19
Low voltage disconnect (LVD)
The CAB constantly monitors battery voltage. During periods of back-up battery
operation, the CAB will progressively reduce the load to prevent deep discharge
of the batteries.
The CAB generates a low voltage disconnect imminent alarm when the battery
terminal voltage reaches –44 V. As the battery voltage level drops further, the
CAB de-energizes the battery contactor at –41V, disconnecting the radios from
the battery power. At 39.5V, the communications contactor is de-energized to
prevent extreme deep discharge of the back up batteries.
The LVD threshold for the communications contactor is lower than that of the
battery contactor, to ensure customer communications equipment remains
powered for as long as possible after radio power has been lost.
NOTE
Once the communications contactor has opened the CAB
will lose all power input connections. CAB functions are
only re-established when the ac supply is restored to the
cabinet. The cabinet then restarts as a normal power up.
Over temperature trip
The CAB generates a cabinet over temperature trip signal when both the 78 C
sensor and the 70 C sensor are active (see Horizon
macro outdoor
temperature control).
The cabinet over temperature trip signal disconnects the battery contactor, the
communications contactor, and disables the TOPSMs. This will shut down the
BTS, and if a shutdown occurs, there is no prior notification to the OMC-R other
than the over temperature alarm.
The CAB re-enables the TOPSMs when both temperature sensors have reset at
60 C. The cabinet then restarts as a normal power up.
Smoke trip
NOTE The following smoke trip functions have not been
implemented in the main cabinet or the auxiliary
equipment housing.
The CAB generates smoke trip control signals after it has been in receipt of a
smoke alarm for 30 seconds.
 The Horizon macro outdoor cabinet smoke trip signal disconnects the
battery contactor, the communications contactor and disables of the
TOPSMs. The BTS will shut down without prior notification to the OMC-R,
other than the smoke alarm.
 A smoke trip signal from the auxiliary equipment housing initiates a remote
disconnection of the external batteries.
Once generated, the smoke trip control signals remain active until the input
mains ac is cycled, or the CAB front panel reset button is operated.