OAS alarm and Control Circuits 6-9
DMS-100 Family Alarm System Description Reference Manual BASE12
communication. In this situation, CC software cannot silence audible
alarms.
When the alarm system generates the dead system alarm, the audible alarm
reset switch connects to the alarm system through contacts in the dead
dystem relays. This reset switch connects to the winding of normally-open
alarm reset relays in the OAU and the standby MTM or ISM. When a dead
system condition occurs, operation of the audible alarm reset switch operates
the two alarm reset relays. These relays open the ground path to the critical
bell in the OAU and the standby MTM or ISM. The alarm reset relays then
lock and the alarm silences. The system automatically releases the alarm
reset relays when the dead system condition clears.
Trunk test center (TTC) alarms
The Trunk Test Center (TTC) is the area of a DMS office that contains the
MAP terminal you use as a trunk test position (TTP). The TTP, which is
described in Lines Maintenance Guide, provides a user interface for the
trunks subsystem of the DMS maintenance system.
The following alarm conditions are related to the TTC:
• incoming call on a 101 communication test line
• trunk group out-of-service alarm
Test line alarm
The 101 test lines terminate at the TTP voice communications module. An
incoming call on one of these lines connects a ground to a scan point in the
OAU. The alarm system software detects the grounded scan point and sets
the SD point assigned for 101 test line seizure. This action sounds the TTC
chime through the operation of a relay in one of the following OAU cards:
• office alarm circuit #2 card (NT2X42).
• OAU alarm transfer card (NT3X83AA, AB, AC, AD, or BA).
When someone answers a call or the calling party disconnects, the system
removes the ground from the scan point and silences the alarm.
Trunk group alarm
The trunk group alarm is a system alarm that the trunk maintenance
subsystem software generates. The number of trunks out of service, system
busy, and manual busy in one trunk group determines the severity of the
alarm: minor, major, or critical. Trunks Maintenance Manual contains
descriptions of the VDU alarm status displays and alarm thresholds for the
trunk group alarms.
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