Power Distribution Center (Pdc) Alarms; Low Voltage And Power Loss Alarm Circuits; Low Battery Voltage Detection Circuit - Nortel DMS-100 Series Reference Manual

6-6 OAS alarm and Control Circuits
Assign one FSP or MSP alarm scan point for each equipment aisle in an
office. For more information, refer to NT5X64 Series Communication
Modules Description, Ordering Information, Installation, Operation, and
Maintenance, 297-1001-157. When an FSP or MSP alarm scan point
detects an aisle alarm loop (FSPA ISxx alarm) a 20 second delay loop will
start in the OAU software. Enable this delay in the software table
OFCENG. If this same alarm occurs more than once in this time period, the
system determines the alarm is a bouncing fan alarm and ignores it. The
system does not generate an alarm condition. Otherwise, the external alarms
subsystem generate a major audible alarm. The subsystem generates the
appropriate display on the MAP terminal VDU. For more information, refer
to External Devices Maintenance Guide, 297-1001-593.

Power distribution center (PDC) alarms

The FSP for the PDC provides the following alarm outputs: alarm battery
supply (ABS), PDC, and aisle alarm loop. The closure of the aisle alarm
loop generates an FSP alarm for the aisle as described in the previous
section. The ABS and PDC alarm outputs from each PDC in an office
connect to the alarm crosspoint field or alarm cross-connect unit (AXU).
These outputs also connect to the DF. The ABS alarms connect to the
ABSFAIL scan point in the OAU. The PDC alarms connect to the
PDCFAIL scan point in the OAU. When the system detects an ABS or PDC
alarm, the External Alarms subsystem generates the appropriate audible and
visual alarms. The FSP alarm, which identifies the aisle that generated the
alarm, always accompanies the ABS FAIL and PDCFAIL alarms. For more
information, refer to NT5X64 Series Communication Modules Description,
Ordering Information, Installation, Operation, and Maintenance,
297-1001-157.
EAS and LPA versions, the NT3X82AC and later versions detect the loss of
the A or B feeds, or both. The NT3X82AC and NT3X82AD cards activate
the critical bell or common audible and the critical power plant lamp. The
A or B feed loss contacts are on the PDC and connect to the NT3X82 cards.
At the PDC, the system powers up the PWR relays if a feed loss at the PDC
occurs.

Low voltage and power loss alarm circuits

The following paragraphs describe low voltage and power loss alarm circuits
in various alarm systems.

Low battery voltage detection circuit

Version 2 enhanced alarm system (EAS)
In the EAS, a low battery voltage detection circuit monitors the -48V office
battery supply (feed). This circuit activates an alarm when the battery
297–1001–122 Standard 06.01 August 1999
cross-connections