Mtm Alarm System Circuits; Alarm Crosspoint Field Shelf - Nortel DMS-100 Series Reference Manual

2-4 Office Alarm System Version 1

MTM alarm system circuits

In the Version 1 OAS, the standby MTM must contain an office alarm
circuit #3 card (NT2X43). This card contains the OAU and dead system
(DS) alarm circuits. The standby MTM must also contain at least one signal
distribution card (NT2X57) and one scan detector card (NT0X10). The
office alarm circuit #3 card provides a backup for the 20-Hz ac ringing and
130 V supplies in the OAU.
To perform the OAU backup functions, the standby MTM receives power
from a different power distribution center (PDC) and battery feed (A/B
supply) than the OAU. You assign the standby MTM to a different network
module.
The control relays in the office alarm circuit #3 card are part of the OAU
and DS alarm circuits. The office alarm circuit #3 card also provides a
transformer for the 'even' aisle multiple of the local talk line circuit. The
signal didtribution and scan detector cards provide scan (SC) and signal
distribution (SD) points associated with the circuits in the office alarm
circuit #3 card.

Alarm crosspoint field shelf

The OAU and standby MTM of the Version 1 OAS both connect to the other
alarm system hardware. The OAU and standby MTM connect through the
alarm crosspoint field shelf (NT0X62AA) and the distribution frame (DF).
The connections between the various hardware modules in the Version 1
OAS are shown in Figure 2-2.
297–1001–122 Standard 06.01 August 1999