Load Bus Low Voltage Alarm - Nortel DMS-100 Series Maintenance Manual

2-38 OPAC maintenance overview
The amber condition occurs if the BCCDVR and OESALRM cards have a
disabled battery rotation audit or a battery string marked F. The F indicates
if the string fails weekly tests.

Load bus low voltage alarm

During a power failure, the system forces battery strings on the load bus.
The system locks the strings to load the bus for the duration of the failure.
The OPAC power backup provides battery power for at least 6.6 h when the
OPAC has equipment that the operating company provides. The equipment
must draw 20 A above the basic OPAC equipment load requirements.
When a power failure occurs
A load bus which, during a power outage, measures 47 V or less, triggers the
low voltage alarm. The load bus is normally 52 V. An MTU tests
equipment.
The discharge rate of the battery strings varies with the OPM load. The
OPAC has a minimum of 6.6 h of backup for the following reserve power
and load conditions:
297-8211-550 Standard 05.01 August 1999
Green—The system does not detect an alarm. Every card and facility
are in service (InSv) or normal.
OffL—The BCCDVR and PESALRM cards are offline. This state does
not affect the PM command OffL. Ignore the alarms that the system can
detect because they are for information only.
A major alarm results.
If the measurement of the load bus voltage reveals a level that is too low,
one of the following events occur:
— The system generates a log that indicates the low voltage in the load
bus.
— A major alarm appears at the PM level of the MAP display
— The command QUERYPES displays the failure status after the post
of the affected OPM.
six strings of Eagle-Picher batteries at 80 % or greater capacity
an OPAC call rate of 3.0 CCS or less